Implement enough wrappers to start the WiFi task

Work in progress. Does not work yet.

Some notes:

  - This requires some changes to TinyGo, look at the espnet branch.
  - The  next step is probably defining all the functions in
    g_wifi_osi_funcs (see espnet.c). Right now it hangs in
    esp_wifi_init_internal, probably a NULL pointer dereference.
  - This is only for the ESP32-C3. This will require some work to work
    on other chips from Espressif.

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "espnet/esp-idf"]
+	path = espnet/esp-idf
+	url = https://github.com/espressif/esp-idf.git

CHANGELOG.md

@@ -1,3 +1,28 @@
+0.17.1
+---
+- To correct an error in the release process. Same as 0.17.0.
+
+0.17.0
+---
+- **new devices**
+    - rtl8720dn: add support for rtl8720dn
+    - sdcard: add support for spi sdcard driver, along with fatfs
+- **enhancements**
+    - apa102: use 4-byte buffer to improve speed
+    - bmi160: avoid heap allocations
+    - ili9341: add standard SPI driver
+    - wifinina
+        - avoid fmt package
+        - Fix RSSI command for WiFiNINA + Print current SSID + Wait for correct time before printing it out + Cleanup
+    - ws2812
+        - rename the pin to ws2812
+        - add tag for nrf52833
+        - Disable interrupts before sending ws2812 data
+        - add support for qtpy and atsame5x
+- **core**
+    - modules: switch to use tinygo-org version of tinyfs package
+    - all: use machine.Serial as the default output
+
 0.16.0
 ---
 - **new devices**

Makefile

@@ -2,7 +2,7 @@
 clean:
 	@rm -rf build
 
-FMT_PATHS = ./*.go ./examples/**/*.go
+FMT_PATHS = ./
 
 fmt-check:
 	@unformatted=$$(gofmt -l $(FMT_PATHS)); [ -z "$$unformatted" ] && exit 0; echo "Unformatted:"; for fn in $$unformatted; do echo "  $$fn"; done; exit 1
@@ -75,6 +75,8 @@ smoke-test:
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=xiao ./examples/ili9341/scroll
 	@md5sum ./build/test.hex
+	tinygo build -size short -o ./build/test.hex -target=pyportal ./examples/ili9341/slideshow
+	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=circuitplay-express ./examples/lis3dh/main.go
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=microbit ./examples/lsm303agr/main.go
@@ -193,12 +195,22 @@ endif
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=nucleo-l432kc ./examples/aht20/main.go
 	@md5sum ./build/test.hex
+	tinygo build -size short -o ./build/test.hex -target=feather-m4 ./examples/sdcard/console/
+	@md5sum ./build/test.hex
+	tinygo build -size short -o ./build/test.hex -target=feather-m4 ./examples/sdcard/tinyfs/
+	@md5sum ./build/test.hex
+	tinygo build -size short -o ./build/test.hex -target=wioterminal ./examples/rtl8720dn/webclient/
+	@md5sum ./build/test.hex
+	tinygo build -size short -o ./build/test.hex -target=wioterminal ./examples/rtl8720dn/webserver/
+	@md5sum ./build/test.hex
+	tinygo build -size short -o ./build/test.hex -target=wioterminal ./examples/rtl8720dn/mqttsub/
+	@md5sum ./build/test.hex
 
 DRIVERS = $(wildcard */)
 NOTESTS = build examples flash semihosting pcd8544 shiftregister st7789 microphone mcp3008 gps microbitmatrix \
 		hcsr04 ssd1331 ws2812 thermistor apa102 easystepper ssd1351 ili9341 wifinina shifter hub75 \
 		hd44780 buzzer ssd1306 espat l9110x st7735 bmi160 l293x dht keypad4x4 max72xx p1am tone tm1637 \
-		pcf8563 mcp2515 servo
+		pcf8563 mcp2515 servo sdcard rtl8720dn image cmd
 TESTS = $(filter-out $(addsuffix /%,$(NOTESTS)),$(DRIVERS))
 
 unit-test:

README.md

@@ -52,7 +52,7 @@ func main() {
 
 ## Currently supported devices
 
-The following 65 devices are supported.
+The following 67 devices are supported.
 
 | Device Name | Interface Type |
 |----------|-------------|
@@ -100,12 +100,14 @@ The following 65 devices are supported.
 | [PCD8544 display](http://eia.udg.edu/~forest/PCD8544_1.pdf) | SPI |
 | [PCF8563 real time clock](https://www.nxp.com/docs/en/data-sheet/PCF8563.pdf) | I2C |
 | [Resistive Touchscreen (4-wire)](http://ww1.microchip.com/downloads/en/Appnotes/doc8091.pdf) | GPIO |
+| [RTL8720DN 2.4G/5G Dual Bands Wireless and BLE5.0](https://www.seeedstudio.com/Realtek8720DN-2-4G-5G-Dual-Bands-Wireless-and-BLE5-0-Combo-Module-p-4442.html) | UART |
 | [Semihosting](https://wiki.segger.com/Semihosting) | Debug |
 | [Servo](https://learn.sparkfun.com/tutorials/hobby-servo-tutorial/all) | PWM |
 | [Shift register (PISO)](https://en.wikipedia.org/wiki/Shift_register#Parallel-in_serial-out_\(PISO\)) | GPIO |
 | [Shift registers (SIPO)](https://en.wikipedia.org/wiki/Shift_register#Serial-in_parallel-out_(SIPO)) | GPIO |
 | [SHT3x Digital Humidity Sensor](https://www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/0_Datasheets/Humidity/Sensirion_Humidity_Sensors_SHT3x_Datasheet_digital.pdf) | I2C |
 | [SPI NOR Flash Memory](https://en.wikipedia.org/wiki/Flash_memory#NOR_flash) | SPI/QSPI |
+| [SPI SDCARD/MMC](https://en.wikipedia.org/wiki/SD_card) | SPI |
 | [SSD1306 OLED display](https://cdn-shop.adafruit.com/datasheets/SSD1306.pdf) | I2C / SPI |
 | [SSD1331 TFT color display](https://www.crystalfontz.com/controllers/SolomonSystech/SSD1331/381/) | SPI |
 | [SSD1351 OLED display](https://download.mikroe.com/documents/datasheets/ssd1351-revision-1.3.pdf) | SPI |

apa102/apa102.go

@@ -27,44 +27,46 @@ var startFrame = []byte{0x00, 0x00, 0x00, 0x00}
 type Device struct {
 	bus   drivers.SPI
 	Order int
+	buf   [4]byte
 }
 
 // New returns a new APA102 driver. Pass in a fully configured SPI bus.
-func New(b drivers.SPI) Device {
-	return Device{bus: b, Order: BGR}
+func New(b drivers.SPI) *Device {
+	return &Device{bus: b, Order: BGR}
 }
 
 // NewSoftwareSPI returns a new APA102 driver that will use a software based
 // implementation of the SPI protocol.
-func NewSoftwareSPI(sckPin, sdoPin machine.Pin, delay uint32) Device {
+func NewSoftwareSPI(sckPin, sdoPin machine.Pin, delay uint32) *Device {
 	return New(&bbSPI{SCK: sckPin, SDO: sdoPin, Delay: delay})
 }
 
 // WriteColors writes the given RGBA color slice out using the APA102 protocol.
 // The A value (Alpha channel) is used for brightness, set to 0xff (255) for maximum.
-func (d Device) WriteColors(cs []color.RGBA) (n int, err error) {
+func (d *Device) WriteColors(cs []color.RGBA) (n int, err error) {
 	d.startFrame()
 
 	// write data
 	for _, c := range cs {
 		// brightness is scaled to 5 bit value
-		d.bus.Transfer(0xe0 | (c.A >> 3))
+		d.buf[0] = 0xe0 | (c.A >> 3)
 
 		// set the colors
 		switch d.Order {
 		case BRG:
-			d.bus.Transfer(c.B)
-			d.bus.Transfer(c.R)
-			d.bus.Transfer(c.G)
+			d.buf[1] = c.B
+			d.buf[2] = c.R
+			d.buf[3] = c.G
 		case GRB:
-			d.bus.Transfer(c.G)
-			d.bus.Transfer(c.R)
-			d.bus.Transfer(c.B)
+			d.buf[1] = c.G
+			d.buf[2] = c.R
+			d.buf[3] = c.B
 		case BGR:
-			d.bus.Transfer(c.B)
-			d.bus.Transfer(c.G)
-			d.bus.Transfer(c.R)
+			d.buf[1] = c.B
+			d.buf[2] = c.G
+			d.buf[3] = c.R
 		}
+		d.bus.Tx(d.buf[:], nil)
 	}
 
 	d.endFrame(len(cs))
@@ -73,7 +75,7 @@ func (d Device) WriteColors(cs []color.RGBA) (n int, err error) {
 }
 
 // Write the raw bytes using the APA102 protocol.
-func (d Device) Write(buf []byte) (n int, err error) {
+func (d *Device) Write(buf []byte) (n int, err error) {
 	d.startFrame()
 	d.bus.Tx(buf, nil)
 	d.endFrame(len(buf) / 4)
@@ -82,14 +84,14 @@ func (d Device) Write(buf []byte) (n int, err error) {
 }
 
 // startFrame sends the start bytes for a strand of LEDs.
-func (d Device) startFrame() {
+func (d *Device) startFrame() {
 	d.bus.Tx(startFrame, nil)
 }
 
 // endFrame sends the end frame marker with one extra bit per LED so
 // long strands of LEDs receive the necessary termination for updates.
 // See https://cpldcpu.wordpress.com/2014/11/30/understanding-the-apa102-superled/
-func (d Device) endFrame(count int) {
+func (d *Device) endFrame(count int) {
 	for i := 0; i < count/16; i++ {
 		d.bus.Transfer(0xff)
 	}

bmi160/bmi160.go

@@ -13,6 +13,8 @@ type DeviceSPI struct {
 	// Chip select pin
 	CSB machine.Pin
 
+	buf [7]byte
+
 	// SPI bus (requires chip select to be usable).
 	Bus drivers.SPI
 }
@@ -80,7 +82,10 @@ func (d *DeviceSPI) Reset() error {
 
 // ReadTemperature returns the temperature in celsius milli degrees (°C/1000).
 func (d *DeviceSPI) ReadTemperature() (temperature int32, err error) {
-	data := []byte{0x80 | reg_TEMPERATURE_0, 0, 0}
+	data := d.buf[:3]
+	data[0] = 0x80 | reg_TEMPERATURE_0
+	data[1] = 0
+	data[2] = 0
 	d.CSB.Low()
 	err = d.Bus.Tx(data, data)
 	d.CSB.High()
@@ -113,7 +118,11 @@ func (d *DeviceSPI) ReadTemperature() (temperature int32, err error) {
 // and the sensor is not moving the returned value will be around 1000000 or
 // -1000000.
 func (d *DeviceSPI) ReadAcceleration() (x int32, y int32, z int32, err error) {
-	data := []byte{0x80 | reg_ACC_XL, 0, 0, 0, 0, 0, 0}
+	data := d.buf[:7]
+	data[0] = 0x80 | reg_ACC_XL
+	for i := 1; i < len(data); i++ {
+		data[i] = 0
+	}
 	d.CSB.Low()
 	err = d.Bus.Tx(data, data)
 	d.CSB.High()
@@ -139,7 +148,11 @@ func (d *DeviceSPI) ReadAcceleration() (x int32, y int32, z int32, err error) {
 // rotation along one axis and while doing so integrate all values over time,
 // you would get a value close to 360000000.
 func (d *DeviceSPI) ReadRotation() (x int32, y int32, z int32, err error) {
-	data := []byte{0x80 | reg_GYR_XL, 0, 0, 0, 0, 0, 0}
+	data := d.buf[:7]
+	data[0] = 0x80 | reg_GYR_XL
+	for i := 1; i < len(data); i++ {
+		data[i] = 0
+	}
 	d.CSB.Low()
 	err = d.Bus.Tx(data, data)
 	d.CSB.High()
@@ -185,7 +198,9 @@ func (d *DeviceSPI) readRegister(address uint8) uint8 {
 	// I don't know why but it appears necessary to sleep for a bit here.
 	time.Sleep(time.Millisecond)
 
-	data := []byte{0x80 | address, 0}
+	data := d.buf[:2]
+	data[0] = 0x80 | address
+	data[1] = 0
 	d.CSB.Low()
 	d.Bus.Tx(data, data)
 	d.CSB.High()
@@ -198,7 +213,11 @@ func (d *DeviceSPI) writeRegister(address, data uint8) {
 	// I don't know why but it appears necessary to sleep for a bit here.
 	time.Sleep(time.Millisecond)
 
+	buf := d.buf[:2]
+	buf[0] = address
+	buf[1] = data
+
 	d.CSB.Low()
-	d.Bus.Tx([]byte{address, data}, []byte{0, 0})
+	d.Bus.Tx(buf, buf)
 	d.CSB.High()
 }

cmd/convert2bin/convert2bin.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"strings"
+)
+
+// See ../../image/README.md for the usage.
+
+func main() {
+	err := run(os.Args)
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func run(args []string) error {
+	if len(args) < 2 {
+		return fmt.Errorf("usage: %s FILE")
+	}
+
+	b, err := ioutil.ReadFile(args[1])
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("const %s = \"\" +\n", strings.Replace(args[1], ".", "_", -1))
+
+	i := 0
+	max := 32
+	for i = 0; i < len(b); i++ {
+		bb := b[i]
+		if (i % max) == 0 {
+			fmt.Printf("	\"")
+		}
+		fmt.Printf("\\x%02X", bb)
+		if (i%max) == max-1 && i != len(b)-1 {
+			fmt.Printf("\" + \n")
+		}
+	}
+	if (i % max) < max-1 {
+		fmt.Printf("\"\n")
+	}
+
+	return nil
+}

dht/highfreq.go

@@ -1,4 +1,5 @@
-// +build mimxrt1062  stm32f405  atsamd51  stm32f103xx  k210  stm32f407
+//go:build mimxrt1062 || stm32f405 || atsamd51 || stm32f103xx || k210 || stm32f407
+// +build mimxrt1062 stm32f405 atsamd51 stm32f103xx k210 stm32f407
 
 package dht // import "tinygo.org/x/drivers/dht"
 

dht/lowfreq.go

@@ -1,4 +1,5 @@
-// +build arduino atmega1284p nrf52840 digispark nrf52 arduino_nano nrf51 atsamd21 fe310 arduino_nano33 circuitplay_express arduino_mega2560
+//go:build !mimxrt1062 && !stm32f405 && !atsamd51 && !stm32f103xx && !k210 && !stm32f407
+// +build !mimxrt1062,!stm32f405,!atsamd51,!stm32f103xx,!k210,!stm32f407
 
 package dht // import "tinygo.org/x/drivers/dht"
 

espnet/ap.go

@@ -0,0 +1,49 @@
+package espnet
+
+/*
+#cgo CFLAGS: -DCONFIG_IDF_TARGET_ESP32C3
+#cgo CFLAGS: -Iinclude
+#cgo CFLAGS: -Iesp-idf/components/esp_common/include
+#cgo CFLAGS: -Iesp-idf/components/esp_event/include
+#cgo CFLAGS: -Iesp-idf/components/esp_netif/include
+#cgo CFLAGS: -Iesp-idf/components/esp_wifi/include
+
+#cgo LDFLAGS: -Lesp-idf/components/esp_wifi/lib/esp32c3 -lnet80211 -lpp -lphy -lmesh -lcore
+#cgo LDFLAGS: -Tesp-idf/components/esp_rom/esp32c3/ld/esp32c3.rom.ld
+
+#include "esp_private/wifi.h"
+#include "esp_wifi_types.h"
+#include "espnet.h"
+*/
+import "C"
+
+import _ "compat/freertos"
+
+type ESPWiFi struct {
+}
+
+var WiFi = &ESPWiFi{}
+
+type Config struct {
+}
+
+var internalConfig = C.wifi_init_config_t{
+	osi_funcs:           &C.g_wifi_osi_funcs,
+	wpa_crypto_funcs:    C.g_wifi_default_wpa_crypto_funcs,
+	static_rx_buf_num:   10,
+	static_tx_buf_num:   10,
+	mgmt_sbuf_num:       6,
+	sta_disconnected_pm: true,
+	magic:               C.WIFI_INIT_CONFIG_MAGIC,
+}
+
+func (wifi ESPWiFi) Configure(config Config) error {
+	C.esp_wifi_internal_set_log_level(5)
+	return makeError(C.esp_wifi_init_internal(&internalConfig))
+}
+
+func (wifi ESPWiFi) AccessPointMAC() ([6]byte, error) {
+	var mac [6]byte
+	errCode := C.esp_wifi_get_mac(C.ESP_IF_WIFI_AP, &mac[0])
+	return mac, makeError(errCode)
+}

espnet/error.go

@@ -0,0 +1,103 @@
+package espnet
+
+// #include <esp_err.h>
+// #include <esp_wifi.h>
+import "C"
+
+// Wrapper for C.esp_err_t. Don't convert a C.esp_err_t to an Error type,
+// instead use makeError to handle ESP_OK.
+type Error C.esp_err_t
+
+// makeError converts a C.esp_err_t into an error or nil depending on whether
+// errCode indicates an error or not.
+func makeError(errCode C.esp_err_t) error {
+	if errCode == C.ESP_OK {
+		return nil
+	}
+	return Error(errCode)
+}
+
+func (e Error) Error() string {
+	switch {
+	case e < C.ESP_ERR_WIFI_BASE:
+		// esp-idf/components/esp_common/include/esp_err.h
+		switch e {
+		case C.ESP_OK:
+			return "OK" // not an error
+		case C.ESP_FAIL:
+			return "ESP FAIL"
+		case C.ESP_ERR_NO_MEM:
+			return "Out of memory"
+		case C.ESP_ERR_INVALID_ARG:
+			return "Invalid argument"
+		case C.ESP_ERR_INVALID_STATE:
+			return "Invalid state"
+		case C.ESP_ERR_INVALID_SIZE:
+			return "Invalid size"
+		case C.ESP_ERR_NOT_FOUND:
+			return "Requested resource not found"
+		case C.ESP_ERR_NOT_SUPPORTED:
+			return "Operation or feature not supported"
+		case C.ESP_ERR_TIMEOUT:
+			return "Operation timed out"
+		case C.ESP_ERR_INVALID_RESPONSE:
+			return "Received response was invalid"
+		case C.ESP_ERR_INVALID_CRC:
+			return "CRC or checksum was invalid"
+		case C.ESP_ERR_INVALID_VERSION:
+			return "Version was invalid"
+		case C.ESP_ERR_INVALID_MAC:
+			return "MAC address was invalid"
+		default:
+			return "Unknown error"
+		}
+	case e >= C.ESP_ERR_WIFI_BASE && e < C.ESP_ERR_MESH_BASE:
+		// esp-idf/components/esp_wifi/include/esp_wifi.h
+		switch e {
+		case C.ESP_ERR_WIFI_NOT_INIT:
+			return "WiFi driver was not installed by esp_wifi_init"
+		case C.ESP_ERR_WIFI_NOT_STARTED:
+			return "WiFi driver was not started by esp_wifi_start"
+		case C.ESP_ERR_WIFI_NOT_STOPPED:
+			return "WiFi driver was not stopped by esp_wifi_stop"
+		case C.ESP_ERR_WIFI_IF:
+			return "WiFi interface error"
+		case C.ESP_ERR_WIFI_MODE:
+			return "WiFi mode error"
+		case C.ESP_ERR_WIFI_STATE:
+			return "WiFi internal state error"
+		case C.ESP_ERR_WIFI_CONN:
+			return "WiFi internal control block of station or soft-AP error"
+		case C.ESP_ERR_WIFI_NVS:
+			return "WiFi internal NVS module error"
+		case C.ESP_ERR_WIFI_MAC:
+			return "MAC address is invalid"
+		case C.ESP_ERR_WIFI_SSID:
+			return " SSID is invalid"
+		case C.ESP_ERR_WIFI_PASSWORD:
+			return "Password is invalid"
+		case C.ESP_ERR_WIFI_TIMEOUT:
+			return "Timeout error"
+		case C.ESP_ERR_WIFI_WAKE_FAIL:
+			return "WiFi is in sleep state(RF closed) and wakeup fail"
+		case C.ESP_ERR_WIFI_WOULD_BLOCK:
+			return "The caller would block"
+		case C.ESP_ERR_WIFI_NOT_CONNECT:
+			return "Station still in disconnect status"
+		case C.ESP_ERR_WIFI_POST:
+			return "Failed to post the event to WiFi task"
+		case C.ESP_ERR_WIFI_INIT_STATE:
+			return "Invalid WiFi state when init/deinit is called"
+		case C.ESP_ERR_WIFI_STOP_STATE:
+			return "Returned when WiFi is stopping"
+		case C.ESP_ERR_WIFI_NOT_ASSOC:
+			return "The WiFi connection is not associated"
+		case C.ESP_ERR_WIFI_TX_DISALLOW:
+			return "The WiFi TX is disallowed"
+		default:
+			return "Other WiFi error"
+		}
+	default:
+		return "Other error"
+	}
+}

espnet/espnet.c

@@ -0,0 +1,829 @@
+#include <stdint.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "espnet.h"
+#include "esp_wifi.h"
+#include "esp_private/wifi.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/semphr.h"
+#include "freertos/task.h"
+
+
+// Stub functions, to know which functions need to be implemented for OS
+// functionality.
+
+static bool _env_is_chip(void) {
+	printf("called: _env_is_chip\n");
+	return false;
+}
+static void _set_intr(int32_t cpu_no, uint32_t intr_source, uint32_t intr_num, int32_t intr_prio) {
+	printf("called: _set_intr\n");
+}
+static void _clear_intr(uint32_t intr_source, uint32_t intr_num) {
+	printf("called: _clear_intr\n");
+}
+static void _set_isr(int32_t n, void *f, void *arg) {
+	printf("called: _set_isr\n");
+}
+static void _ints_on(uint32_t mask) {
+	printf("called: _ints_on\n");
+}
+static void _ints_off(uint32_t mask) {
+	printf("called: _ints_off\n");
+}
+static bool _is_from_isr(void) {
+	printf("called: _is_from_isr\n");
+	return false;
+}
+
+// Having conflict between when include 
+// #include "freertos/portmacro.h" 
+
+typedef struct {
+	/* owner field values:
+	 * 0				- Uninitialized (invalid)
+	 * portMUX_FREE_VAL - Mux is free, can be locked by either CPU
+	 * CORE_ID_REGVAL_PRO / CORE_ID_REGVAL_APP - Mux is locked to the particular core
+	 *
+	 *
+	 * Any value other than portMUX_FREE_VAL, CORE_ID_REGVAL_PRO, CORE_ID_REGVAL_APP indicates corruption
+	 */
+	uint32_t owner;
+	/* count field:
+	 * If mux is unlocked, count should be zero.
+	 * If mux is locked, count is non-zero & represents the number of recursive locks on the mux.
+	 */
+	uint32_t count;
+} portMUX_TYPE;
+
+#define portMUX_FREE_VAL	SPINLOCK_FREE
+#define SPINLOCK_FREE	   0xB33FFFFF
+
+#define portMUX_INITIALIZER_UNLOCKED {					\
+		.owner = portMUX_FREE_VAL,						\
+		.count = 0,										\
+	}
+
+static void * _spin_lock_create(void) {
+	portMUX_TYPE tmp = portMUX_INITIALIZER_UNLOCKED;
+	void *mux = malloc(sizeof(portMUX_TYPE));
+	if (mux) {
+		memcpy(mux,&tmp,sizeof(portMUX_TYPE));
+		return mux;
+	}
+	return NULL;
+}
+static void _spin_lock_delete(void *lock) {
+	free(lock);
+}
+static uint32_t _wifi_int_disable(void *wifi_int_mux) {
+	printf("called: _wifi_int_disable\n");
+	return 0;
+}
+static void _wifi_int_restore(void *wifi_int_mux, uint32_t tmp) {
+	printf("called: _wifi_int_restore\n");
+}
+static void _task_yield_from_isr(void) {
+	printf("called: _task_yield_from_isr\n");
+}
+static void *_semphr_create(uint32_t max, uint32_t init) {
+	return (void *)xSemaphoreCreateCounting(max, init);
+}
+static void _semphr_delete(void *semphr) {
+	vSemaphoreDelete(semphr);
+}
+static int32_t _semphr_take(void *semphr, uint32_t block_time_tick) {
+	if (block_time_tick == OSI_FUNCS_TIME_BLOCKING) {
+		return (int32_t)xSemaphoreTake(semphr, portMAX_DELAY);
+	} else {
+		return (int32_t)xSemaphoreTake(semphr, block_time_tick);
+	}
+}
+static int32_t _semphr_give(void *semphr) {
+	return (int32_t)xSemaphoreGive(semphr);
+}
+static void *_wifi_thread_semphr_get(void) {
+	static SemaphoreHandle_t sem = NULL;
+	if (!sem) {
+		sem = xSemaphoreCreateCounting(1, 0);
+	}
+	return (void*)sem;
+}
+static void *_mutex_create(void) {
+	printf("called: _mutex_create\n");
+	return NULL;
+}
+
+static void *_recursive_mutex_create(void) {
+	return xSemaphoreCreateRecursiveMutex();
+}
+static void _mutex_delete(void *mutex) {
+	return vSemaphoreDelete(mutex);
+}
+static int32_t _mutex_lock(void *mutex) {
+	return (int32_t)xSemaphoreTakeRecursive(mutex, portMAX_DELAY);
+}
+static int32_t _mutex_unlock(void *mutex) {
+	return (int32_t)xSemaphoreGiveRecursive(mutex);
+}
+static void * _queue_create(uint32_t queue_len, uint32_t item_size) {
+	printf("called: _queue_create\n");
+	return NULL;
+}
+static void _queue_delete(void *queue) {
+	printf("called: _queue_delete\n");
+}
+static int32_t _queue_send(void *queue, void *item, uint32_t block_time_tick) {
+	if (block_time_tick == OSI_FUNCS_TIME_BLOCKING) {
+		return (int32_t)xQueueSend(queue, item, portMAX_DELAY);
+	} else {
+		return (int32_t)xQueueSend(queue, item, block_time_tick);
+	}
+}
+static int32_t _queue_send_from_isr(void *queue, void *item, void *hptw) {
+	printf("called: _queue_send_from_isr\n");
+	return 0;
+}
+static int32_t _queue_send_to_back(void *queue, void *item, uint32_t block_time_tick) {
+	printf("called: _queue_send_to_back\n");
+	return 0;
+}
+static int32_t _queue_send_to_front(void *queue, void *item, uint32_t block_time_tick) {
+	printf("called: _queue_send_to_front\n");
+	return 0;
+}
+static int32_t _queue_recv(void *queue, void *item, uint32_t block_time_tick) {
+	if (block_time_tick == OSI_FUNCS_TIME_BLOCKING) {
+		return (int32_t)xQueueReceive(queue, item, portMAX_DELAY);
+	} else {
+		return (int32_t)xQueueReceive(queue, item, block_time_tick);
+	}
+}
+static void * _event_group_create(void) {
+	printf("called: _event_group_create\n");
+	return NULL;
+}
+static void _event_group_delete(void *event) {
+	printf("called: _event_group_delete\n");
+}
+static uint32_t _event_group_set_bits(void *event, uint32_t bits) {
+	printf("called: _event_group_set_bits\n");
+	return 0;
+}
+static uint32_t _event_group_clear_bits(void *event, uint32_t bits) {
+	printf("called: _event_group_clear_bits\n");
+	return 0;
+}
+static uint32_t _event_group_wait_bits(void *event, uint32_t bits_to_wait_for, int clear_on_exit, int wait_for_all_bits, uint32_t block_time_tick) {
+	printf("called: _event_group_wait_bits\n");
+	return 0;
+}
+
+#define P(x) printf("called: "#x"\n");
+
+static int32_t _task_create_pinned_to_core(void *task_func, const char *name, uint32_t stack_depth, void *param, uint32_t prio, void *task_handle, uint32_t core_id) {
+	// Note: using xTaskCreate instead of xTaskCreatePinnedToCore.
+	return (uint32_t)xTaskCreate(task_func, name, stack_depth, param, prio, task_handle);
+}
+static int32_t _task_create(void *task_func, const char *name, uint32_t stack_depth, void *param, uint32_t prio, void *task_handle) {
+	P(_task_create)
+	return 0;
+}
+static void _task_delete(void *task_handle) {
+	P(_task_delete)
+}
+static int32_t _task_ms_to_tick(uint32_t ms) {
+	return (int32_t)(ms / portTICK_PERIOD_MS);
+}
+static int32_t _task_get_max_priority() {
+	return configMAX_PRIORITIES;
+}
+static int32_t _event_post(const char* event_base, int32_t event_id, void* event_data, size_t event_data_size, uint32_t ticks_to_wait) {
+	P(_event_post)
+	return 0;
+}
+static uint32_t  _get_free_heap_size(void) {
+	P(_get_free_heap_size)
+	return 0;
+}
+static uint32_t  _rand(void) {
+	P(_rand)
+	return 0;
+}
+static void _dport_access_stall_other_cpu_start_wrap(void) {
+	P(_dport_access_stall_other_cpu_start_wrap)
+}
+static void _dport_access_stall_other_cpu_end_wrap(void) {
+	P(_dport_access_stall_other_cpu_end_wrap)
+}
+static void _wifi_apb80m_request(void) {
+	P(_wifi_apb80m_request)
+}
+static void _wifi_apb80m_release(void) {
+	P(_wifi_apb80m_release)
+}
+static void _phy_disable(void) {
+	P(_phy_disable)
+}
+static void _phy_enable(void) {
+	P(_phy_enable)
+}
+static int _phy_update_country_info(const char* country) {
+	P(_phy_update_country_info)
+	return 0;
+}
+static int _read_mac(uint8_t* mac, uint32_t type) {
+	P(_read_mac)
+	return 0;
+}
+static void _timer_arm(void *timer, uint32_t tmout, bool repeat) {
+	P(_timer_arm)
+}
+static void _timer_disarm(void *timer) {
+	P(_timer_disarm)
+}
+static void _timer_done(void *ptimer) {
+	P(_timer_done)
+}
+static void _timer_setfn(void *ptimer, void *pfunction, void *parg) {
+	P(_timer_setfn)
+}
+static void _timer_arm_us(void *ptimer, uint32_t us, bool repeat) {
+	P(_timer_arm_us)
+}
+static void _wifi_reset_mac(void) {
+	P(_wifi_reset_mac)
+}
+static void _wifi_clock_enable(void) {
+	P(_wifi_clock_enable)
+}
+static void _wifi_clock_disable(void) {
+	P(_wifi_clock_disable)
+}
+static void _wifi_rtc_enable_iso(void) {
+	P(_wifi_rtc_enable_iso)
+}
+static void _wifi_rtc_disable_iso(void) {
+	P(_wifi_rtc_disable_iso)
+}
+static int64_t _esp_timer_get_time(void) {
+	P(_esp_timer_get_time)
+	return 0;
+}
+static int _nvs_set_i8(uint32_t handle, const char* key, int8_t value) {
+	P(_nvs_set_i8)
+	return 0;
+}
+static int _nvs_get_i8(uint32_t handle, const char* key, int8_t* out_value) {
+	P(_nvs_get_i8)
+	return 0;
+}
+static int _nvs_set_u8(uint32_t handle, const char* key, uint8_t value) {
+	P(_nvs_set_u8)
+	return 0;
+}
+static int _nvs_get_u8(uint32_t handle, const char* key, uint8_t* out_value) {
+	P(_nvs_get_u8)
+	return 0;
+}
+static int _nvs_set_u16(uint32_t handle, const char* key, uint16_t value) {
+	P(_nvs_set_u16)
+	return 0;
+}
+static int _nvs_get_u16(uint32_t handle, const char* key, uint16_t* out_value) {
+	P(_nvs_get_u16)
+	return 0;
+}
+static int _nvs_open(const char* name, uint32_t open_mode, uint32_t *out_handle) {
+	P(_nvs_open)
+	return 0;
+}
+static void _nvs_close(uint32_t handle) {
+	P(_nvs_close)
+}
+static int _nvs_commit(uint32_t handle) {
+	P(_nvs_commit)
+	return 0;
+}
+static int _nvs_set_blob(uint32_t handle, const char* key, const void* value, size_t length) {
+	P(_nvs_set_blob)
+	return 0;
+}
+static int _nvs_get_blob(uint32_t handle, const char* key, void* out_value, size_t* length) {
+	P(_nvs_get_blob)
+	return 0;
+}
+static int _nvs_erase_key(uint32_t handle, const char* key) {
+	P(_nvs_erase_key)
+	return 0;
+}
+static int _get_random(uint8_t *buf, size_t len) {
+	P(_get_random)
+	return 0;
+}
+static int _get_time(void *t) {
+	P(_get_time)
+	return 0;
+}
+static unsigned long _random(void) {
+	P(_random)
+	return 0;
+}
+// #if CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32S3 || CONFIG_IDF_TARGET_ESP32C3
+//	 uint32_t (* _slowclk_cal_get(void)
+// #endif
+static void _log_write(uint32_t level, const char* tag, const char* format, ...) {
+	va_list argList;
+	printf("[%s] ", tag);
+	va_start(argList, format);
+	vprintf(format, argList);
+	va_end(argList);
+	printf("\n");
+}
+static void _log_writev(uint32_t level, const char* tag, const char* format, va_list args) {
+	printf("[%s] ", tag);
+	vprintf(format, args);
+	printf("\n");
+}
+
+static uint32_t  _log_timestamp(void) {
+	P(_log_timestamp)
+	return 0;
+}
+static void* _malloc_internal(size_t size) {
+	printf("called: _malloc_internal(%d)\n", size);
+	return malloc(size);
+}
+static void* _realloc_internal(void *ptr, size_t size) {
+	printf("called: _realloc_internal(%p,%d)\n", ptr, size);
+	return NULL;
+}
+
+static void* _calloc_internal(size_t n, size_t size) {
+	printf("called: _calloc_internal(%d,%d)\n", n, size);
+	return malloc(n * size);
+}
+static void* _zalloc_internal(size_t size) {
+	printf("called: _zalloc_internal(%d)\n", size);
+	return NULL;
+}
+static void* _wifi_malloc(size_t size) {
+	return malloc(size);
+}
+static void* _wifi_realloc(void *ptr, size_t size) {
+	printf("called: _wifi_realloc(%d)\n", size);
+	return NULL;
+}
+static void* _wifi_calloc(size_t n, size_t size) {
+	return calloc(n, size);
+}
+static void* _wifi_zalloc(size_t size) {
+	return calloc(1, size);
+}
+static void* _wifi_create_queue(int queue_len, int item_size) {
+	wifi_static_queue_t *queue = (wifi_static_queue_t*)malloc(sizeof(wifi_static_queue_t));
+	queue->handle = xQueueCreate( queue_len, item_size);
+	return queue;
+}
+static void _wifi_delete_queue(void * queue) {
+	vQueueDelete(queue);
+}
+static int _coex_init(void) {
+	P(_coex_init)
+	return 0;
+}
+static void _coex_deinit(void) {
+	P(_coex_deinit)
+}
+static int _coex_enable(void) {
+	P(_coex_enable)
+	return 0;
+}
+static void _coex_disable(void) {
+	P(_coex_disable)
+}
+static uint32_t  _coex_status_get(void) {
+	P(_coex_status_get)
+	return 0;
+}
+static void _coex_condition_set(uint32_t type, bool dissatisfy) {
+	P(_coex_condition_set)
+}
+static int _coex_wifi_request(uint32_t event, uint32_t latency, uint32_t duration) {
+	P(_coex_wifi_request)
+	return 0;
+}
+static int _coex_wifi_release(uint32_t event) {
+	P(_coex_wifi_release)
+	return 0;
+}
+static int _coex_wifi_channel_set(uint8_t primary, uint8_t secondary) {
+	P(_coex_wifi_channel_set)
+	return 0;
+}
+static int _coex_event_duration_get(uint32_t event, uint32_t *duration) {
+	P(_coex_event_duration_get)
+	return 0;
+}
+static int _coex_pti_get(uint32_t event, uint8_t *pti) {
+	P(_coex_pti_get)
+	return 0;
+}
+static void _coex_schm_status_bit_clear(uint32_t type, uint32_t status) {
+	P(_coex_schm_status_bit_clear)
+}
+static void _coex_schm_status_bit_set(uint32_t type, uint32_t status) {
+	P(_coex_schm_status_bit_set)
+}
+static int _coex_schm_interval_set(uint32_t interval) {
+	P(_coex_schm_interval_set)
+	return 0;
+}
+static uint32_t  _coex_schm_interval_get(void) {
+	P(_coex_schm_interval_get)
+	return 0;
+}
+static uint8_t _coex_schm_curr_period_get(void) {
+	P(_coex_schm_curr_period_get)
+	return 0;
+}
+static void* _coex_schm_curr_phase_get(void) {
+	P(_coex_schm_curr_phase_get)
+	return NULL;
+}
+static int _coex_schm_curr_phase_idx_set(int idx) {
+	P(_coex_schm_curr_phase_idx_set)
+	return 0;
+}
+static int _coex_schm_curr_phase_idx_get(void) {
+	P(_coex_schm_curr_phase_idx_get)
+	return 0;
+}
+
+
+uint32_t _slowclk_cal_get(void) {
+	return 0;
+}
+
+// OS adapter functions.
+// See: esp-idf/components/esp_wifi/include/esp_private/wifi_os_adapter.h
+wifi_osi_funcs_t g_wifi_osi_funcs = {
+	._version = ESP_WIFI_OS_ADAPTER_VERSION,
+	._env_is_chip = _env_is_chip,
+	._set_intr = _set_intr,
+	._clear_intr = _clear_intr,
+	._set_isr = _set_isr,
+	._ints_on = _ints_on,
+	._ints_off = _ints_off,
+	._is_from_isr = _is_from_isr,
+	._spin_lock_create = _spin_lock_create,
+	._spin_lock_delete = _spin_lock_delete,
+	._wifi_int_disable = _wifi_int_disable,
+	._wifi_int_restore = _wifi_int_restore,
+	._task_yield_from_isr = _task_yield_from_isr,
+	._semphr_create = _semphr_create,
+	._semphr_delete = _semphr_delete,
+	._semphr_take = _semphr_take,
+	._semphr_give = _semphr_give,
+	._wifi_thread_semphr_get = _wifi_thread_semphr_get,
+	._mutex_create = _mutex_create,
+	._recursive_mutex_create = _recursive_mutex_create,
+	._mutex_delete = _mutex_delete,
+	._mutex_lock = _mutex_lock,
+	._mutex_unlock = _mutex_unlock,
+	._queue_create = _queue_create,
+	._queue_delete = _queue_delete,
+	._queue_send = _queue_send,
+	._queue_send_from_isr = _queue_send_from_isr,
+	._queue_send_to_back = _queue_send_to_back,
+	._queue_send_to_front = _queue_send_to_front,
+	._queue_recv = _queue_recv,
+	._queue_msg_waiting = (uint32_t(*)(void *))uxQueueMessagesWaiting,
+	._event_group_create = _event_group_create,
+	._event_group_delete = _event_group_delete,
+	._event_group_set_bits = _event_group_set_bits,
+	._event_group_clear_bits = _event_group_clear_bits,
+	._event_group_wait_bits = _event_group_wait_bits,
+	._task_create_pinned_to_core = _task_create_pinned_to_core,
+	._task_create = _task_create,
+	._task_delete = _task_delete,
+	._task_delay = vTaskDelay,
+	._task_ms_to_tick = _task_ms_to_tick,
+	._task_get_current_task = (void *(*)(void))xTaskGetCurrentTaskHandle,
+	._task_get_max_priority = _task_get_max_priority,
+	._malloc = malloc,
+	._free = free,
+	._event_post = _event_post,
+	._get_free_heap_size = _get_free_heap_size,
+	._rand = _rand,
+	._dport_access_stall_other_cpu_start_wrap = _dport_access_stall_other_cpu_start_wrap,
+	._dport_access_stall_other_cpu_end_wrap = _dport_access_stall_other_cpu_end_wrap,
+	._wifi_apb80m_request = _wifi_apb80m_request,
+	._wifi_apb80m_release = _wifi_apb80m_release,
+	._phy_disable = _phy_disable,
+	._phy_enable = _phy_enable,
+	._phy_update_country_info = _phy_update_country_info,
+	._read_mac = _read_mac,
+	._timer_arm = _timer_arm,
+	._timer_disarm = _timer_disarm,
+	._timer_done = _timer_done,
+	._timer_setfn = _timer_setfn,
+	._timer_arm_us = _timer_arm_us,
+	._wifi_reset_mac = _wifi_reset_mac,
+	._wifi_clock_enable = _wifi_clock_enable,
+	._wifi_clock_disable = _wifi_clock_disable,
+	._wifi_rtc_enable_iso = _wifi_rtc_enable_iso,
+	._wifi_rtc_disable_iso = _wifi_rtc_disable_iso,
+	._esp_timer_get_time = _esp_timer_get_time,
+	._nvs_set_i8 = _nvs_set_i8,
+	._nvs_get_i8 = _nvs_get_i8,
+	._nvs_set_u8 = _nvs_set_u8,
+	._nvs_get_u8 = _nvs_get_u8,
+	._nvs_set_u16 = _nvs_set_u16,
+	._nvs_get_u16 = _nvs_get_u16,
+	._nvs_open = _nvs_open,
+	._nvs_close = _nvs_close,
+	._nvs_commit = _nvs_commit,
+	._nvs_set_blob = _nvs_set_blob,
+	._nvs_get_blob = _nvs_get_blob,
+	._nvs_erase_key = _nvs_erase_key,
+	._get_random = _get_random,
+	._get_time = _get_time,
+	._random = _random,
+#if CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32S3 || CONFIG_IDF_TARGET_ESP32C3
+	._slowclk_cal_get = _slowclk_cal_get,
+#endif
+	._log_write = _log_write,
+	._log_writev = _log_writev,
+	._log_timestamp = _log_timestamp,
+	._malloc_internal = _malloc_internal,
+	._realloc_internal = _realloc_internal,
+	._calloc_internal = _calloc_internal,
+	._zalloc_internal = _zalloc_internal,
+	._wifi_malloc = _wifi_malloc,
+	._wifi_realloc = _wifi_realloc,
+	._wifi_calloc = _wifi_calloc,
+	._wifi_zalloc = _wifi_zalloc,
+	._wifi_create_queue = _wifi_create_queue,
+	._wifi_delete_queue = _wifi_delete_queue,
+	._coex_init = _coex_init,
+	._coex_deinit = _coex_deinit,
+	._coex_enable = _coex_enable,
+	._coex_disable = _coex_disable,
+	._coex_status_get = _coex_status_get,
+	._coex_condition_set = _coex_condition_set,
+	._coex_wifi_request = _coex_wifi_request,
+	._coex_wifi_release = _coex_wifi_release,
+	._coex_wifi_channel_set = _coex_wifi_channel_set,
+	._coex_event_duration_get = _coex_event_duration_get,
+	._coex_pti_get = _coex_pti_get,
+	._coex_schm_status_bit_clear = _coex_schm_status_bit_clear,
+	._coex_schm_status_bit_set = _coex_schm_status_bit_set,
+	._coex_schm_interval_set = _coex_schm_interval_set,
+	._coex_schm_interval_get = _coex_schm_interval_get,
+	._coex_schm_curr_period_get = _coex_schm_curr_period_get,
+	._coex_schm_curr_phase_get = _coex_schm_curr_phase_get,
+	._coex_schm_curr_phase_idx_set = _coex_schm_curr_phase_idx_set,
+	._coex_schm_curr_phase_idx_get = _coex_schm_curr_phase_idx_get,
+
+	._magic = ESP_WIFI_OS_ADAPTER_MAGIC,
+};
+
+static int esp_aes_wrap(const unsigned char *kek, int n, const unsigned char *plain, unsigned char *cipher) {
+	P(aes_wrap)
+	return -1;
+}
+static int esp_aes_unwrap(const unsigned char *kek, int n, const unsigned char *cipher, unsigned char *plain) {
+	P(aes_unwrap)
+	return -1;	
+}
+static int hmac_sha256_vector(const unsigned char *key, int key_len, int num_elem,
+	const unsigned char *addr[], const int *len, unsigned char *mac) {
+	return -1;
+}
+static int sha256_prf(const unsigned char *key, int key_len, const char *label,
+								   const unsigned char *data, int data_len, unsigned char *buf, int buf_len) {
+	P(sha256_prf)
+	return -1;
+}
+static int hmac_md5(const unsigned char *key, unsigned int key_len, const unsigned char *data,
+							  unsigned int data_len, unsigned char *mac) {
+	P(hmac_md5)
+	return -1;
+}
+static int hamc_md5_vector(const unsigned char *key, unsigned int key_len, unsigned int num_elem,
+							  const unsigned char *addr[], const unsigned int *len, unsigned char *mac) {
+	P(hamc_md5_vector)
+	return -1;							
+}
+static int hmac_sha1(const unsigned char *key, unsigned int key_len, const unsigned char *data,
+							  unsigned int data_len, unsigned char *mac) {
+	P(hmac_sha1)
+	return -1;
+}
+static int hmac_sha1_vector(const unsigned char *key, unsigned int key_len, unsigned int num_elem,
+							  const unsigned char *addr[], const unsigned int *len, unsigned char *mac) {
+	P(hmac_sha1_vector)
+	return -1;
+}
+static int sha1_prf(const unsigned char *key, unsigned int key_len, const char *label,
+							  const unsigned char *data, unsigned int data_len, unsigned char *buf, unsigned int buf_len) {
+	P(sha1_prf)
+	return -1;
+}
+static int sha1_vector(unsigned int num_elem, const unsigned char *addr[], const unsigned int *len,
+							  unsigned char *mac) {
+	P(sha1_vector)
+	return -1;
+}
+static int pbkdf2_sha1(const char *passphrase, const char *ssid, unsigned int ssid_len,
+							  int iterations, unsigned char *buf, unsigned int buflen) {
+	P(pbkdf2_sha1)
+	return -1;
+}
+static int rc4_skip(const unsigned char *key, unsigned int keylen, unsigned int skip,
+							  unsigned char *data, unsigned int data_len) {
+	P(rc4_skip)
+	return -1;
+}
+static int md5_vector(unsigned int num_elem, const unsigned char *addr[], const unsigned int *len,
+							  unsigned char *mac) {
+	P(md5_vector)
+	return -1;
+}
+static void aes_encrypt(void *ctx, const unsigned char *plain, unsigned char *crypt) {
+	P(aes_encrypt)
+}
+static void * aes_encrypt_init(const unsigned char *key,  unsigned int len) {
+	P(aes_encrypt_init)
+	return NULL;
+}
+static void aes_encrypt_deinit(void *ctx) {
+	P(aes_encrypt_deinit)
+}
+static void aes_decrypt(void *ctx, const unsigned char *crypt, unsigned char *plain) {
+	P(aes_decrypt)
+}
+static void * aes_decrypt_init(const unsigned char *key, unsigned int len) {
+	P(aes_decrypt_init)
+	return NULL;
+}
+static void aes_decrypt_deinit(void *ctx) {
+	P(aes_decrypt_deinit)
+}
+static int aes_128_decrypt(const unsigned char *key, const unsigned char *iv, unsigned char *data, int data_len) {
+	P(aes_128_decrypt)
+	return -1;
+}
+static int omac1_aes_128(const uint8_t *key, const uint8_t *data, size_t data_len,
+								   uint8_t *mic) {
+	P(omac1_aes_128)
+	return -1;
+}
+static uint8_t * ccmp_decrypt(const uint8_t *tk, const uint8_t *ieee80211_hdr,
+										const uint8_t *data, size_t data_len,
+										size_t *decrypted_len, bool espnow_pkt) {
+	P(ccmp_decrypt)
+	return NULL;
+}
+static uint8_t * ccmp_encrypt(const uint8_t *tk, uint8_t *frame, size_t len, size_t hdrlen,
+										uint8_t *pn, int keyid, size_t *encrypted_len) {
+	P(ccmp_encrypt)
+	return NULL;
+}
+static int hmac_md5_vector(const unsigned char *key, unsigned int key_len, unsigned int num_elem,
+							  const unsigned char *addr[], const unsigned int *len, unsigned char *mac) {
+	P(hmac_md5_vector)
+	return -1;
+}
+static void esp_aes_encrypt(void *ctx, const unsigned char *plain, unsigned char *crypt) {
+	P(esp_aes_encrypt)
+}
+static void esp_aes_decrypt(void *ctx, const unsigned char *crypt, unsigned char *plain) {
+	P(esp_aes_decrypt)
+}
+static int aes_128_cbc_encrypt(const unsigned char *key, const unsigned char *iv, unsigned char *data, int data_len) {
+	P(aes_128_cbc_encrypt)
+	return -1;
+}
+static int aes_128_cbc_decrypt(const unsigned char *key, const unsigned char *iv, unsigned char *data, int data_len) {
+	P(aes_128_cbc_decrypt)
+	return -1;
+}
+
+const wpa_crypto_funcs_t g_wifi_default_wpa_crypto_funcs = {
+	.size = sizeof(wpa_crypto_funcs_t),
+	.version = ESP_WIFI_CRYPTO_VERSION,
+	.aes_wrap = (esp_aes_wrap_t)esp_aes_wrap,
+	.aes_unwrap = (esp_aes_unwrap_t)esp_aes_unwrap,
+	.hmac_sha256_vector = (esp_hmac_sha256_vector_t)hmac_sha256_vector,
+	.sha256_prf = (esp_sha256_prf_t)sha256_prf,
+	.hmac_md5 = (esp_hmac_md5_t)hmac_md5,
+	.hamc_md5_vector = (esp_hmac_md5_vector_t)hmac_md5_vector,
+	.hmac_sha1 = (esp_hmac_sha1_t)hmac_sha1,
+	.hmac_sha1_vector = (esp_hmac_sha1_vector_t)hmac_sha1_vector,
+	.sha1_prf = (esp_sha1_prf_t)sha1_prf,
+	.sha1_vector = (esp_sha1_vector_t)sha1_vector,
+	.pbkdf2_sha1 = (esp_pbkdf2_sha1_t)pbkdf2_sha1,
+	.rc4_skip = (esp_rc4_skip_t)rc4_skip,
+	.md5_vector = (esp_md5_vector_t)md5_vector,
+	.aes_encrypt = (esp_aes_encrypt_t)esp_aes_encrypt,
+	.aes_encrypt_init = (esp_aes_encrypt_init_t)aes_encrypt_init,
+	.aes_encrypt_deinit = (esp_aes_encrypt_deinit_t)aes_encrypt_deinit,
+	.aes_decrypt = (esp_aes_decrypt_t)esp_aes_decrypt,
+	.aes_decrypt_init = (esp_aes_decrypt_init_t)aes_decrypt_init,
+	.aes_decrypt_deinit = (esp_aes_decrypt_deinit_t)aes_decrypt_deinit,
+	.aes_128_encrypt = (esp_aes_128_encrypt_t)aes_128_cbc_encrypt,
+	.aes_128_decrypt = (esp_aes_128_decrypt_t)aes_128_cbc_decrypt,
+	.omac1_aes_128 = (esp_omac1_aes_128_t)omac1_aes_128,
+	.ccmp_decrypt = (esp_ccmp_decrypt_t)ccmp_decrypt,
+	.ccmp_encrypt = (esp_ccmp_encrypt_t)ccmp_encrypt
+};
+
+// This is a string constant that is used all over ESP-IDF and is also used by
+// libnet80211.a. The main purpose is to be a fixed pointer that can be compared
+// against etc.
+const char *WIFI_EVENT = "WIFI_EVENT";
+
+// Required by libphy.a
+int phy_printf(const char *format, ...) {
+	va_list args;
+	va_start(args, format);
+	printf("phy: ");
+	int res = vprintf(format, args);
+	va_end(args);
+	return res;
+}
+
+// Required by libpp.a
+int pp_printf(const char *format, ...) {
+	va_list args;
+	va_start(args, format);
+	printf("pp: ");
+	int res = vprintf(format, args);
+	va_end(args);
+	return res;
+}
+
+// Required by libnet80211.a
+int net80211_printf(const char *format, ...) {
+	va_list args;
+	va_start(args, format);
+	printf("net80211: ");
+	int res = vprintf(format, args);
+	va_end(args);
+	return res;
+}
+
+// Source: esp-idf/components/wpa_supplicant/src/utils/common.c
+static int hex2num(char c)
+{
+	if (c >= '0' && c <= '9')
+		return c - '0';
+	if (c >= 'a' && c <= 'f')
+		return c - 'a' + 10;
+	if (c >= 'A' && c <= 'F')
+		return c - 'A' + 10;
+	return -1;
+}
+
+// Source: esp-idf/components/wpa_supplicant/src/utils/common.c
+int hex2byte(const char *hex)
+{
+	int a, b;
+	a = hex2num(*hex++);
+	if (a < 0)
+		return -1;
+	b = hex2num(*hex++);
+	if (b < 0)
+		return -1;
+	return (a << 4) | b;
+}
+
+// Source: esp-idf/components/wpa_supplicant/src/utils/common.c
+/**
+ * hexstr2bin - Convert ASCII hex string into binary data
+ * @hex: ASCII hex string (e.g., "01ab")
+ * @buf: Buffer for the binary data
+ * @len: Length of the text to convert in bytes (of buf); hex will be double
+ * this size
+ * Returns: 0 on success, -1 on failure (invalid hex string)
+ */
+int hexstr2bin(const char *hex, uint8_t *buf, size_t len)
+{
+	size_t i;
+	int a;
+	const char *ipos = hex;
+	uint8_t *opos = buf;
+
+	for (i = 0; i < len; i++) {
+		a = hex2byte(ipos);
+		if (a < 0)
+			return -1;
+		*opos++ = a;
+		ipos += 2;
+	}
+	return 0;
+}

espnet/espnet.h

@@ -0,0 +1,5 @@
+#include <stdbool.h>
+
+#include "esp_private/wifi_os_adapter.h"
+
+extern wifi_osi_funcs_t g_wifi_osi_funcs;

examples/apa102/itsybitsy-m0/main.go

@@ -13,7 +13,7 @@ import (
 )
 
 var (
-	apa apa102.Device
+	apa *apa102.Device
 
 	pwm   = machine.TCC0
 	leds  = make([]color.RGBA, 1)

examples/espat/espconsole/main.go

@@ -30,7 +30,7 @@ var (
 	tx   = machine.PA22
 	rx   = machine.PA23
 
-	console = machine.UART0
+	console = machine.Serial
 
 	adaptor *espat.Device
 )

examples/espat/mqttclient/main.go

@@ -36,7 +36,7 @@ var (
 	tx   = machine.PA22
 	rx   = machine.PA23
 
-	console = machine.UART0
+	console = machine.Serial
 
 	adaptor *espat.Device
 	topic   = "tinygo"

examples/espat/mqttsub/main.go

@@ -37,7 +37,7 @@ var (
 	tx   = machine.PA22
 	rx   = machine.PA23
 
-	console = machine.UART0
+	console = machine.Serial
 
 	adaptor *espat.Device
 	cl      mqtt.Client

examples/espnet/main.go

@@ -0,0 +1,20 @@
+package main
+
+import "tinygo.org/x/drivers/espnet"
+
+func main() {
+	err := espnet.WiFi.Configure(espnet.Config{})
+	if err != nil {
+		println("failed to configure:", err.Error())
+	}
+	mac, err := espnet.WiFi.AccessPointMAC()
+	if err != nil {
+		println("failed to read MAC address:", err.Error())
+		return
+	}
+	print("MAC address:")
+	for _, b := range mac {
+		print(" ", b)
+	}
+	println()
+}

examples/flash/console/console_example.go

@@ -20,7 +20,7 @@ var (
 	input [consoleBufLen]byte
 	store [storageBufLen]byte
 
-	console = machine.UART0
+	console = machine.Serial
 
 	dev *flash.Device
 

examples/gps/uart/main.go

@@ -10,7 +10,7 @@ import (
 func main() {
 	println("GPS UART Example")
 	machine.UART1.Configure(machine.UARTConfig{BaudRate: 9600})
-	ublox := gps.NewUART(&machine.UART1)
+	ublox := gps.NewUART(machine.UART1)
 	parser := gps.NewParser()
 	var fix gps.Fix
 	for {

examples/ili9341/basic/atsamd21.go

@@ -1,3 +1,4 @@
+//go:build atsamd21
 // +build atsamd21
 
 package main

examples/ili9341/basic/pyportal.go

@@ -1,3 +1,4 @@
+//go:build pyportal
 // +build pyportal
 
 package main

examples/ili9341/basic/wioterminal.go

@@ -1,3 +1,4 @@
+//go:build wioterminal
 // +build wioterminal
 
 package main

examples/ili9341/pyportal_boing/main.go

@@ -25,7 +25,7 @@ const (
 )
 
 var (
-	frameBuffer = [(graphics.BALLHEIGHT + 8) * (graphics.BALLWIDTH + 8)]uint16{}
+	frameBuffer = [(graphics.BALLHEIGHT + 8) * (graphics.BALLWIDTH + 8) * 2]uint8{}
 
 	startTime int64
 	frame     int64
@@ -179,7 +179,8 @@ func main() {
 						c = BGCOLOR
 					}
 				}
-				frameBuffer[y*int(width)+x] = c
+				frameBuffer[(y*int(width)+x)*2] = byte(c >> 8)
+				frameBuffer[(y*int(width)+x)*2+1] = byte(c)
 				bx1++ // Increment bitmap position counters (X axis)
 				bgx1++
 			}
@@ -190,7 +191,7 @@ func main() {
 			bgy++
 		}
 
-		display.DrawRGBBitmap(minx, miny, frameBuffer[:width*height], width, height)
+		display.DrawRGBBitmap8(minx, miny, frameBuffer[:width*height*2], width, height)
 
 		// Show approximate frame rate
 		frame++
@@ -215,11 +216,13 @@ func DrawBackground() {
 				b = graphics.Background[j*byteWidth+k/8]
 			}
 			if b&0x80 == 0 {
-				frameBuffer[k] = BGCOLOR
+				frameBuffer[2*k] = byte(BGCOLOR >> 8)
+				frameBuffer[2*k+1] = byte(BGCOLOR & 0xFF)
 			} else {
-				frameBuffer[k] = GRIDCOLOR
+				frameBuffer[2*k] = byte(GRIDCOLOR >> 8)
+				frameBuffer[2*k+1] = byte(GRIDCOLOR & 0xFF)
 			}
 		}
-		display.DrawRGBBitmap(0, j, frameBuffer[0:w], w, 1)
+		display.DrawRGBBitmap8(0, j, frameBuffer[0:w*2], w, 1)
 	}
 }

examples/ili9341/pyportal_boing/pyportal.go

@@ -1,3 +1,4 @@
+//go:build pyportal
 // +build pyportal
 
 package main

examples/ili9341/pyportal_boing/wioterminal.go

@@ -1,3 +1,4 @@
+//go:build wioterminal
 // +build wioterminal
 
 package main

examples/ili9341/scroll/atsamd21.go

@@ -1,3 +1,4 @@
+//go:build atsamd21
 // +build atsamd21
 
 package main

examples/ili9341/scroll/pyportal.go

@@ -1,3 +1,4 @@
+//go:build pyportal
 // +build pyportal
 
 package main

examples/ili9341/scroll/wioterminal.go

@@ -1,3 +1,4 @@
+//go:build wioterminal
 // +build wioterminal
 
 package main

examples/ili9341/slideshow/README.md

@@ -0,0 +1,18 @@
+# examples/ili9341/slideshow
+
+![](./slideshow.jpg)
+
+This example uses the image package for TinyGo to display png and jpeg images.  
+
+## How to create an image
+
+The following program will output an image binary like the one in [images.go](./images.go).  
+
+```
+go run ./examples/ili9341/slideshow/convert2bin ./path/to/png_or_jpg.png
+```
+
+## Notes
+
+Displaying a 320x240 png or jpeg often requires more than 50KB of memory.  
+The examples include samd21 settings, but if you run them as is, you will get a memory size error.  

examples/ili9341/slideshow/atsamd21.go

@@ -0,0 +1,30 @@
+//go:build atsamd21
+// +build atsamd21
+
+package main
+
+import (
+	"machine"
+
+	"tinygo.org/x/drivers/ili9341"
+)
+
+var (
+	display = ili9341.NewSPI(
+		machine.SPI0,
+		machine.D0,
+		machine.D1,
+		machine.D2,
+	)
+
+	backlight = machine.D3
+)
+
+func init() {
+	machine.SPI0.Configure(machine.SPIConfig{
+		SCK:       machine.SPI0_SCK_PIN,
+		SDO:       machine.SPI0_SDO_PIN,
+		SDI:       machine.SPI0_SDI_PIN,
+		Frequency: 24000000,
+	})
+}

examples/ili9341/slideshow/main.go

@@ -0,0 +1,94 @@
+package main
+
+import (
+	"fmt"
+	"image/color"
+	"machine"
+	"strings"
+	"time"
+
+	"tinygo.org/x/drivers/ili9341"
+	"tinygo.org/x/drivers/image/jpeg"
+	"tinygo.org/x/drivers/image/png"
+)
+
+var (
+	black = color.RGBA{0, 0, 0, 255}
+	white = color.RGBA{255, 255, 255, 255}
+	red   = color.RGBA{255, 0, 0, 255}
+	blue  = color.RGBA{0, 0, 255, 255}
+	green = color.RGBA{0, 255, 0, 255}
+)
+
+func main() {
+	err := run()
+	for err != nil {
+		errorMessage(err)
+	}
+}
+
+func run() error {
+	backlight.Configure(machine.PinConfig{machine.PinOutput})
+
+	display.Configure(ili9341.Config{})
+
+	width, height := display.Size()
+	if width < 320 || height < 240 {
+		display.SetRotation(ili9341.Rotation270)
+	}
+
+	display.FillScreen(black)
+	backlight.High()
+
+	for {
+		err := drawJpeg(display)
+		if err != nil {
+			return err
+		}
+		time.Sleep(time.Second)
+
+		err = drawPng(display)
+		if err != nil {
+			return err
+		}
+		time.Sleep(time.Second)
+	}
+
+	return nil
+}
+
+// Define the buffer required for the callback. In most cases, this setting
+// should be sufficient.  For jpeg, the callback will always be called every
+// 3*8*8*4 pix. png will be called every line, i.e. every width pix.
+var buffer [3 * 8 * 8 * 4]uint16
+
+func drawPng(display *ili9341.Device) error {
+	p := strings.NewReader(pngImage)
+	png.SetCallback(buffer[:], func(data []uint16, x, y, w, h, width, height int16) {
+		err := display.DrawRGBBitmap(x, y, data[:w*h], w, h)
+		if err != nil {
+			errorMessage(fmt.Errorf("error drawPng: %s", err))
+		}
+	})
+
+	return png.Decode(p)
+}
+
+func drawJpeg(display *ili9341.Device) error {
+	p := strings.NewReader(jpegImage)
+	jpeg.SetCallback(buffer[:], func(data []uint16, x, y, w, h, width, height int16) {
+		err := display.DrawRGBBitmap(x, y, data[:w*h], w, h)
+		if err != nil {
+			errorMessage(fmt.Errorf("error drawJpeg: %s", err))
+		}
+	})
+
+	return jpeg.Decode(p)
+}
+
+func errorMessage(err error) {
+	for {
+		fmt.Printf("%s\r\n", err.Error())
+		time.Sleep(5 * time.Second)
+	}
+}

examples/ili9341/slideshow/pyportal.go

@@ -0,0 +1,23 @@
+//go:build pyportal
+// +build pyportal
+
+package main
+
+import (
+	"machine"
+
+	"tinygo.org/x/drivers/ili9341"
+)
+
+var (
+	display = ili9341.NewParallel(
+		machine.LCD_DATA0,
+		machine.TFT_WR,
+		machine.TFT_DC,
+		machine.TFT_CS,
+		machine.TFT_RESET,
+		machine.TFT_RD,
+	)
+
+	backlight = machine.TFT_BACKLIGHT
+)

examples/ili9341/slideshow/wioterminal.go

@@ -0,0 +1,30 @@
+//go:build wioterminal
+// +build wioterminal
+
+package main
+
+import (
+	"machine"
+
+	"tinygo.org/x/drivers/ili9341"
+)
+
+var (
+	display = ili9341.NewSPI(
+		machine.SPI3,
+		machine.LCD_DC,
+		machine.LCD_SS_PIN,
+		machine.LCD_RESET,
+	)
+
+	backlight = machine.LCD_BACKLIGHT
+)
+
+func init() {
+	machine.SPI3.Configure(machine.SPIConfig{
+		SCK:       machine.LCD_SCK_PIN,
+		SDO:       machine.LCD_SDO_PIN,
+		SDI:       machine.LCD_SDI_PIN,
+		Frequency: 40000000,
+	})
+}

examples/lsm6dsox/main.go

@@ -0,0 +1,108 @@
+// Connects to an LSM6DSOX I2C a 6 axis Inertial Measurement Unit (IMU)
+package main
+
+import (
+	"fmt"
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/lsm6dsox"
+)
+
+const (
+	PLOTTER           = true
+	SHOW_ACCELERATION = false
+	SHOW_ROTATION     = true
+	SHOW_TEMPERATURE  = false
+
+	// calibration is naive, good enough for a demo: do not shake a second after flashing
+	GYRO_CALIBRATION = true
+)
+
+var cal = [...]float32{0, 0, 0}
+
+func main() {
+
+	machine.I2C0.Configure(machine.I2CConfig{})
+
+	device := lsm6dsox.New(machine.I2C0)
+	device.Configure(lsm6dsox.Configuration{
+		AccelRange:      lsm6dsox.ACCEL_2G,
+		AccelSampleRate: lsm6dsox.ACCEL_SR_104,
+		GyroRange:       lsm6dsox.GYRO_250DPS,
+		GyroSampleRate:  lsm6dsox.GYRO_SR_104,
+	})
+
+	for {
+
+		if !device.Connected() {
+			println("LSM6DSOX not connected")
+			time.Sleep(time.Second)
+			continue
+		}
+
+		// heuristic: after successful calibration the value can't be 0
+		if GYRO_CALIBRATION && cal[0] == 0 {
+			calibrateGyro(device)
+		}
+
+		ax, ay, az := device.ReadAcceleration()
+		gx, gy, gz := device.ReadRotation()
+		t, _ := device.ReadTemperature()
+
+		if PLOTTER {
+			printPlotter(ax, ay, az, gx, gy, gz, t)
+			time.Sleep(time.Millisecond * 100)
+		} else {
+			printMonitor(ax, ay, az, gx, gy, gz, t)
+			time.Sleep(time.Millisecond * 1000)
+		}
+
+	}
+
+}
+
+func calibrateGyro(device *lsm6dsox.Device) {
+	for i := 0; i < 100; i++ {
+		gx, gy, gz := device.ReadRotation()
+		cal[0] += float32(gx) / 1000000
+		cal[1] += float32(gy) / 1000000
+		cal[2] += float32(gz) / 1000000
+		time.Sleep(time.Millisecond * 10)
+	}
+	cal[0] /= 100
+	cal[1] /= 100
+	cal[2] /= 100
+}
+
+// Arduino IDE's Serial Plotter
+func printPlotter(ax, ay, az, gx, gy, gz, t int32) {
+	if SHOW_ACCELERATION {
+		fmt.Printf("AX:%f, AY:%f, AZ:%f,", axis(ax, 0), axis(ay, 0), axis(az, 0))
+	}
+	if SHOW_ROTATION {
+		fmt.Printf("GX:%f, GY:%f, GZ:%f,", axis(gx, cal[0]), axis(gy, cal[1]), axis(gz, cal[2]))
+	}
+	if SHOW_TEMPERATURE {
+		fmt.Printf("T:%f", float32(t)/1000)
+	}
+	println()
+}
+
+// Any Serial Monitor
+func printMonitor(ax, ay, az, gx, gy, gz, t int32) {
+	if SHOW_ACCELERATION {
+		fmt.Printf("Acceleration: %f, %f, %f\r\n", axis(ax, 0), axis(ay, 0), axis(az, 0))
+	}
+	if SHOW_ROTATION {
+		fmt.Printf("Rotation: %f, %f, %f\r\n", axis(gx, cal[0]), axis(gy, cal[1]), axis(gz, cal[2]))
+	}
+	if SHOW_TEMPERATURE {
+		fmt.Printf("Temperature C: %f\r\n", float32(t)/1000)
+	}
+	println()
+}
+
+func axis(raw int32, cal float32) float32 {
+	return float32(raw)/1000000 - cal
+}

examples/rtl8720dn/mqttclient/main.go

@@ -0,0 +1,131 @@
+// This is a sensor station that uses a RTL8720DN running on the device UART2.
+// It creates an MQTT connection that publishes a message every second
+// to an MQTT broker.
+//
+// In other words:
+// Your computer <--> USB-CDC <--> MCU <--> UART2 <--> RTL8720DN <--> Internet <--> MQTT broker.
+//
+// You must install the Paho MQTT package to build this program:
+//
+// 		go get -u github.com/eclipse/paho.mqtt.golang
+//
+// You can check that mqttpub is running successfully with the following command.
+//
+// 		mosquitto_sub -h test.mosquitto.org -t tinygo
+//
+package main
+
+import (
+	"fmt"
+	"math/rand"
+	"time"
+
+	"tinygo.org/x/drivers/net"
+	"tinygo.org/x/drivers/net/mqtt"
+	"tinygo.org/x/drivers/rtl8720dn"
+)
+
+// You can override the setting with the init() in another source code.
+// func init() {
+//    ssid = "your-ssid"
+//    password = "your-password"
+//    debug = true
+//    server = "tinygo.org"
+// }
+
+var (
+	ssid     string
+	password string
+	server   string = "tcp://test.mosquitto.org:1883"
+	debug           = false
+)
+
+var buf [0x400]byte
+
+var lastRequestTime time.Time
+var conn net.Conn
+var adaptor *rtl8720dn.RTL8720DN
+
+func main() {
+	err := run()
+	for err != nil {
+		fmt.Printf("error: %s\r\n", err.Error())
+		time.Sleep(5 * time.Second)
+	}
+}
+
+var (
+	topic = "tinygo"
+)
+
+func run() error {
+	rtl, err := setupRTL8720DN()
+	if err != nil {
+		return err
+	}
+	net.UseDriver(rtl)
+
+	err = rtl.ConnectToAP(ssid, password)
+	if err != nil {
+		return err
+	}
+
+	ip, subnet, gateway, err := rtl.GetIP()
+	if err != nil {
+		return err
+	}
+	fmt.Printf("IP Address : %s\r\n", ip)
+	fmt.Printf("Mask       : %s\r\n", subnet)
+	fmt.Printf("Gateway    : %s\r\n", gateway)
+
+	rand.Seed(time.Now().UnixNano())
+
+	opts := mqtt.NewClientOptions()
+	opts.AddBroker(server).SetClientID("tinygo-client-" + randomString(10))
+
+	println("Connectng to MQTT...")
+	cl := mqtt.NewClient(opts)
+	if token := cl.Connect(); token.Wait() && token.Error() != nil {
+		failMessage(token.Error().Error())
+	}
+
+	for i := 0; ; i++ {
+		println("Publishing MQTT message...")
+		data := []byte(fmt.Sprintf(`{"e":[{"n":"hello %d","v":101}]}`, i))
+		token := cl.Publish(topic, 0, false, data)
+		token.Wait()
+		if err := token.Error(); err != nil {
+			return err
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+
+	// Right now this code is never reached. Need a way to trigger it...
+	println("Disconnecting MQTT...")
+	cl.Disconnect(100)
+
+	println("Done.")
+
+	return nil
+}
+
+// Returns an int >= min, < max
+func randomInt(min, max int) int {
+	return min + rand.Intn(max-min)
+}
+
+// Generate a random string of A-Z chars with len = l
+func randomString(len int) string {
+	bytes := make([]byte, len)
+	for i := 0; i < len; i++ {
+		bytes[i] = byte(randomInt(65, 90))
+	}
+	return string(bytes)
+}
+
+func failMessage(msg string) {
+	for {
+		println(msg)
+		time.Sleep(1 * time.Second)
+	}
+}

examples/rtl8720dn/mqttclient/wioterminal.go

@@ -0,0 +1,74 @@
+//go:build wioterminal
+// +build wioterminal
+
+package main
+
+import (
+	"device/sam"
+	"machine"
+	"runtime/interrupt"
+	"time"
+
+	"tinygo.org/x/drivers/rtl8720dn"
+)
+
+var (
+	uart UARTx
+)
+
+func handleInterrupt(interrupt.Interrupt) {
+	// should reset IRQ
+	uart.Receive(byte((uart.Bus.DATA.Get() & 0xFF)))
+	uart.Bus.INTFLAG.SetBits(sam.SERCOM_USART_INT_INTFLAG_RXC)
+}
+
+func setupRTL8720DN() (*rtl8720dn.RTL8720DN, error) {
+	machine.RTL8720D_CHIP_PU.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	machine.RTL8720D_CHIP_PU.Low()
+	time.Sleep(100 * time.Millisecond)
+	machine.RTL8720D_CHIP_PU.High()
+	time.Sleep(1000 * time.Millisecond)
+	if debug {
+		waitSerial()
+	}
+
+	uart = UARTx{
+		UART: &machine.UART{
+			Buffer: machine.NewRingBuffer(),
+			Bus:    sam.SERCOM0_USART_INT,
+			SERCOM: 0,
+		},
+	}
+
+	uart.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, handleInterrupt)
+	uart.Configure(machine.UARTConfig{TX: machine.PB24, RX: machine.PC24, BaudRate: 614400})
+
+	rtl := rtl8720dn.New(uart)
+	rtl.Debug(debug)
+
+	_, err := rtl.Rpc_tcpip_adapter_init()
+	if err != nil {
+		return nil, err
+	}
+
+	return rtl, nil
+}
+
+// Wait for user to open serial console
+func waitSerial() {
+	for !machine.Serial.DTR() {
+		time.Sleep(100 * time.Millisecond)
+	}
+}
+
+type UARTx struct {
+	*machine.UART
+}
+
+func (u UARTx) Read(p []byte) (n int, err error) {
+	if u.Buffered() == 0 {
+		time.Sleep(1 * time.Millisecond)
+		return 0, nil
+	}
+	return u.UART.Read(p)
+}

examples/rtl8720dn/mqttsub/main.go

@@ -0,0 +1,154 @@
+// This is a sensor station that uses a RTL8720DN running on the device UART2.
+// It creates an MQTT connection that publishes a message every second
+// to an MQTT broker.
+//
+// In other words:
+// Your computer <--> USB-CDC <--> MCU <--> UART2 <--> RTL8720DN <--> Internet <--> MQTT broker.
+//
+// You must also install the Paho MQTT package to build this program:
+//
+// 		go get -u github.com/eclipse/paho.mqtt.golang
+//
+// You can check that mqttpub/mqttsub is running successfully with the following command.
+//
+// 		mosquitto_sub -h test.mosquitto.org -t tinygo/tx
+// 		mosquitto_pub -h test.mosquitto.org -t tinygo/rx -m "hello world"
+//
+package main
+
+import (
+	"fmt"
+	"math/rand"
+	"time"
+
+	"tinygo.org/x/drivers/net"
+	"tinygo.org/x/drivers/net/mqtt"
+	"tinygo.org/x/drivers/rtl8720dn"
+)
+
+// You can override the setting with the init() in another source code.
+// func init() {
+//    ssid = "your-ssid"
+//    password = "your-password"
+//    debug = true
+//    server = "tinygo.org"
+// }
+
+var (
+	ssid     string
+	password string
+	server   string = "tcp://test.mosquitto.org:1883"
+	debug           = false
+)
+
+var buf [0x400]byte
+
+var lastRequestTime time.Time
+var conn net.Conn
+var adaptor *rtl8720dn.RTL8720DN
+
+func main() {
+	err := run()
+	for err != nil {
+		fmt.Printf("error: %s\r\n", err.Error())
+		time.Sleep(5 * time.Second)
+	}
+}
+
+// change these to connect to a different UART or pins for the ESP8266/ESP32
+var (
+	cl      mqtt.Client
+	topicTx = "tinygo/tx"
+	topicRx = "tinygo/rx"
+)
+
+func subHandler(client mqtt.Client, msg mqtt.Message) {
+	fmt.Printf("[%s]  ", msg.Topic())
+	fmt.Printf("%s\r\n", msg.Payload())
+}
+
+func run() error {
+	rtl, err := setupRTL8720DN()
+	if err != nil {
+		return err
+	}
+	net.UseDriver(rtl)
+
+	err = rtl.ConnectToAP(ssid, password)
+	if err != nil {
+		return err
+	}
+
+	ip, subnet, gateway, err := rtl.GetIP()
+	if err != nil {
+		return err
+	}
+	fmt.Printf("IP Address : %s\r\n", ip)
+	fmt.Printf("Mask       : %s\r\n", subnet)
+	fmt.Printf("Gateway    : %s\r\n", gateway)
+
+	rand.Seed(time.Now().UnixNano())
+
+	opts := mqtt.NewClientOptions()
+	opts.AddBroker(server).SetClientID("tinygo-client-" + randomString(10))
+
+	println("Connecting to MQTT broker at", server)
+	cl = mqtt.NewClient(opts)
+	if token := cl.Connect(); token.Wait() && token.Error() != nil {
+		failMessage(token.Error().Error())
+	}
+
+	// subscribe
+	token := cl.Subscribe(topicRx, 0, subHandler)
+	token.Wait()
+	if token.Error() != nil {
+		failMessage(token.Error().Error())
+	}
+
+	go publishing()
+
+	select {}
+
+	// Right now this code is never reached. Need a way to trigger it...
+	println("Disconnecting MQTT...")
+	cl.Disconnect(100)
+
+	println("Done.")
+
+	return nil
+}
+
+func publishing() {
+	for i := 0; ; i++ {
+		println("Publishing MQTT message...")
+		data := []byte(fmt.Sprintf(`{"e":[{"n":"hello %d","v":101}]}`, i))
+		token := cl.Publish(topicTx, 0, false, data)
+		token.Wait()
+		if token.Error() != nil {
+			println(token.Error().Error())
+		}
+
+		time.Sleep(20 * 100 * time.Millisecond)
+	}
+}
+
+// Returns an int >= min, < max
+func randomInt(min, max int) int {
+	return min + rand.Intn(max-min)
+}
+
+// Generate a random string of A-Z chars with len = l
+func randomString(len int) string {
+	bytes := make([]byte, len)
+	for i := 0; i < len; i++ {
+		bytes[i] = byte(randomInt(65, 90))
+	}
+	return string(bytes)
+}
+
+func failMessage(msg string) {
+	for {
+		println(msg)
+		time.Sleep(1 * time.Second)
+	}
+}

examples/rtl8720dn/mqttsub/wioterminal.go

@@ -0,0 +1,74 @@
+//go:build wioterminal
+// +build wioterminal
+
+package main
+
+import (
+	"device/sam"
+	"machine"
+	"runtime/interrupt"
+	"time"
+
+	"tinygo.org/x/drivers/rtl8720dn"
+)
+
+var (
+	uart UARTx
+)
+
+func handleInterrupt(interrupt.Interrupt) {
+	// should reset IRQ
+	uart.Receive(byte((uart.Bus.DATA.Get() & 0xFF)))
+	uart.Bus.INTFLAG.SetBits(sam.SERCOM_USART_INT_INTFLAG_RXC)
+}
+
+func setupRTL8720DN() (*rtl8720dn.RTL8720DN, error) {
+	machine.RTL8720D_CHIP_PU.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	machine.RTL8720D_CHIP_PU.Low()
+	time.Sleep(100 * time.Millisecond)
+	machine.RTL8720D_CHIP_PU.High()
+	time.Sleep(1000 * time.Millisecond)
+	if debug {
+		waitSerial()
+	}
+
+	uart = UARTx{
+		UART: &machine.UART{
+			Buffer: machine.NewRingBuffer(),
+			Bus:    sam.SERCOM0_USART_INT,
+			SERCOM: 0,
+		},
+	}
+
+	uart.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, handleInterrupt)
+	uart.Configure(machine.UARTConfig{TX: machine.PB24, RX: machine.PC24, BaudRate: 614400})
+
+	rtl := rtl8720dn.New(uart)
+	rtl.Debug(debug)
+
+	_, err := rtl.Rpc_tcpip_adapter_init()
+	if err != nil {
+		return nil, err
+	}
+
+	return rtl, nil
+}
+
+// Wait for user to open serial console
+func waitSerial() {
+	for !machine.Serial.DTR() {
+		time.Sleep(100 * time.Millisecond)
+	}
+}
+
+type UARTx struct {
+	*machine.UART
+}
+
+func (u UARTx) Read(p []byte) (n int, err error) {
+	if u.Buffered() == 0 {
+		time.Sleep(1 * time.Millisecond)
+		return 0, nil
+	}
+	return u.UART.Read(p)
+}

examples/rtl8720dn/ntpclient/main.go

@@ -0,0 +1,144 @@
+// This is an example of using the rtl8720dn driver to implement a NTP client.
+// It creates a UDP connection to request the current time and parse the
+// response from a NTP server.
+package main
+
+import (
+	"errors"
+	"fmt"
+	"runtime"
+	"time"
+
+	"tinygo.org/x/drivers/net"
+)
+
+// IP address of the server aka "hub". Replace with your own info.
+// You can override the setting with the init() in another source code.
+// func init() {
+//    ssid = "your-ssid"
+//    password = "your-password"
+//    ntpHost = "129.6.15.29"
+//    debug = true
+// }
+
+var (
+	ssid     string
+	password string
+	ntpHost  = "129.6.15.29"
+	debug    = false
+)
+
+const NTP_PACKET_SIZE = 48
+
+var b = make([]byte, NTP_PACKET_SIZE)
+
+func main() {
+	err := run()
+	for err != nil {
+		fmt.Printf("error: %s\r\n", err.Error())
+		time.Sleep(5 * time.Second)
+	}
+}
+
+func run() error {
+	rtl, err := setupRTL8720DN()
+	if err != nil {
+		return err
+	}
+	net.UseDriver(rtl)
+
+	err = rtl.ConnectToAP(ssid, password)
+	if err != nil {
+		return err
+	}
+
+	ip, subnet, gateway, err := rtl.GetIP()
+	if err != nil {
+		return err
+	}
+	fmt.Printf("IP Address : %s\r\n", ip)
+	fmt.Printf("Mask       : %s\r\n", subnet)
+	fmt.Printf("Gateway    : %s\r\n", gateway)
+
+	// now make UDP connection
+	hip := net.ParseIP(ntpHost)
+	raddr := &net.UDPAddr{IP: hip, Port: 123}
+	laddr := &net.UDPAddr{Port: 2390}
+	conn, err := net.DialUDP("udp", laddr, raddr)
+	if err != nil {
+		return err
+	}
+
+	for {
+		// send data
+		println("Requesting NTP time...")
+		t, err := getCurrentTime(conn)
+		if err != nil {
+			message("Error getting current time: %v", err)
+		} else {
+			message("NTP time: %v", t)
+		}
+		runtime.AdjustTimeOffset(-1 * int64(time.Since(t)))
+		for i := 0; i < 10; i++ {
+			message("Current time: %v", time.Now())
+			time.Sleep(1 * time.Second)
+		}
+	}
+
+}
+
+func getCurrentTime(conn *net.UDPSerialConn) (time.Time, error) {
+	if err := sendNTPpacket(conn); err != nil {
+		return time.Time{}, err
+	}
+	clearBuffer()
+	for now := time.Now(); time.Since(now) < time.Second; {
+		time.Sleep(5 * time.Millisecond)
+		if n, err := conn.Read(b); err != nil {
+			return time.Time{}, fmt.Errorf("error reading UDP packet: %w", err)
+		} else if n == 0 {
+			continue // no packet received yet
+		} else if n != NTP_PACKET_SIZE {
+			if n != NTP_PACKET_SIZE {
+				return time.Time{}, fmt.Errorf("expected NTP packet size of %d: %d", NTP_PACKET_SIZE, n)
+			}
+		}
+		return parseNTPpacket(), nil
+	}
+	return time.Time{}, errors.New("no packet received after 1 second")
+}
+
+func sendNTPpacket(conn *net.UDPSerialConn) error {
+	clearBuffer()
+	b[0] = 0b11100011 // LI, Version, Mode
+	b[1] = 0          // Stratum, or type of clock
+	b[2] = 6          // Polling Interval
+	b[3] = 0xEC       // Peer Clock Precision
+	// 8 bytes of zero for Root Delay & Root Dispersion
+	b[12] = 49
+	b[13] = 0x4E
+	b[14] = 49
+	b[15] = 52
+	if _, err := conn.Write(b); err != nil {
+		return err
+	}
+	return nil
+}
+
+func parseNTPpacket() time.Time {
+	// the timestamp starts at byte 40 of the received packet and is four bytes,
+	// this is NTP time (seconds since Jan 1 1900):
+	t := uint32(b[40])<<24 | uint32(b[41])<<16 | uint32(b[42])<<8 | uint32(b[43])
+	const seventyYears = 2208988800
+	return time.Unix(int64(t-seventyYears), 0)
+}
+
+func clearBuffer() {
+	for i := range b {
+		b[i] = 0
+	}
+}
+
+func message(format string, args ...interface{}) {
+	println(fmt.Sprintf(format, args...), "\r")
+}

examples/rtl8720dn/ntpclient/wioterminal.go

@@ -0,0 +1,72 @@
+//go:build wioterminal
+// +build wioterminal
+
+package main
+
+import (
+	"device/sam"
+	"machine"
+	"runtime/interrupt"
+	"time"
+
+	"tinygo.org/x/drivers/rtl8720dn"
+)
+
+var (
+	uart UARTx
+)
+
+func handleInterrupt(interrupt.Interrupt) {
+	// should reset IRQ
+	uart.Receive(byte((uart.Bus.DATA.Get() & 0xFF)))
+	uart.Bus.INTFLAG.SetBits(sam.SERCOM_USART_INT_INTFLAG_RXC)
+}
+
+func setupRTL8720DN() (*rtl8720dn.RTL8720DN, error) {
+	machine.RTL8720D_CHIP_PU.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	machine.RTL8720D_CHIP_PU.Low()
+	time.Sleep(100 * time.Millisecond)
+	machine.RTL8720D_CHIP_PU.High()
+	time.Sleep(1000 * time.Millisecond)
+	waitSerial()
+
+	uart = UARTx{
+		UART: &machine.UART{
+			Buffer: machine.NewRingBuffer(),
+			Bus:    sam.SERCOM0_USART_INT,
+			SERCOM: 0,
+		},
+	}
+
+	uart.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, handleInterrupt)
+	uart.Configure(machine.UARTConfig{TX: machine.PB24, RX: machine.PC24, BaudRate: 614400})
+
+	rtl := rtl8720dn.New(uart)
+	rtl.Debug(debug)
+
+	_, err := rtl.Rpc_tcpip_adapter_init()
+	if err != nil {
+		return nil, err
+	}
+
+	return rtl, nil
+}
+
+// Wait for user to open serial console
+func waitSerial() {
+	for !machine.Serial.DTR() {
+		time.Sleep(100 * time.Millisecond)
+	}
+}
+
+type UARTx struct {
+	*machine.UART
+}
+
+func (u UARTx) Read(p []byte) (n int, err error) {
+	if u.Buffered() == 0 {
+		time.Sleep(1 * time.Millisecond)
+		return 0, nil
+	}
+	return u.UART.Read(p)
+}

examples/rtl8720dn/tcpclient/main.go

@@ -0,0 +1,121 @@
+// This example opens a TCP connection using a device with RTL8720DN firmware
+// and sends some data, for the purpose of testing speed and connectivity.
+//
+// You can open a server to accept connections from this program using:
+//
+// nc -w 5 -lk 8080
+//
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"time"
+
+	"tinygo.org/x/drivers/net"
+)
+
+// You can override the setting with the init() in another source code.
+// func init() {
+//    ssid = "sghome-gw"
+//    password = "3af25537b4524"
+//    serverIP = "192.168.1.119"
+//    debug = true
+// }
+
+var (
+	ssid     string
+	password string
+	serverIP = ""
+	debug    = false
+)
+
+var buf = &bytes.Buffer{}
+
+func main() {
+	err := run()
+	for err != nil {
+		fmt.Printf("error: %s\r\n", err.Error())
+		time.Sleep(5 * time.Second)
+	}
+}
+
+func run() error {
+	rtl, err := setupRTL8720DN()
+	if err != nil {
+		return err
+	}
+	net.UseDriver(rtl)
+
+	err = rtl.ConnectToAP(ssid, password)
+	if err != nil {
+		return err
+	}
+
+	ip, subnet, gateway, err := rtl.GetIP()
+	if err != nil {
+		return err
+	}
+	fmt.Printf("IP Address : %s\r\n", ip)
+	fmt.Printf("Mask       : %s\r\n", subnet)
+	fmt.Printf("Gateway    : %s\r\n", gateway)
+
+	for {
+		sendBatch()
+		time.Sleep(500 * time.Millisecond)
+	}
+	println("Done.")
+
+	return nil
+}
+
+func sendBatch() {
+
+	// make TCP connection
+	ip := net.ParseIP(serverIP)
+	raddr := &net.TCPAddr{IP: ip, Port: 8080}
+	laddr := &net.TCPAddr{Port: 8080}
+
+	message("---------------\r\nDialing TCP connection")
+	conn, err := net.DialTCP("tcp", laddr, raddr)
+	for ; err != nil; conn, err = net.DialTCP("tcp", laddr, raddr) {
+		message(err.Error())
+		time.Sleep(5 * time.Second)
+	}
+
+	n := 0
+	w := 0
+	start := time.Now()
+
+	// send data
+	message("Sending data")
+
+	for i := 0; i < 1000; i++ {
+		buf.Reset()
+		fmt.Fprint(buf,
+			"\r---------------------------- i == ", i, " ----------------------------"+
+				"\r---------------------------- i == ", i, " ----------------------------")
+		if w, err = conn.Write(buf.Bytes()); err != nil {
+			println("error:", err.Error(), "\r")
+			continue
+		}
+		n += w
+	}
+
+	buf.Reset()
+	ms := time.Now().Sub(start).Milliseconds()
+	fmt.Fprint(buf, "\nWrote ", n, " bytes in ", ms, " ms\r\n")
+	message(buf.String())
+
+	if _, err := conn.Write(buf.Bytes()); err != nil {
+		println("error:", err.Error(), "\r")
+	}
+
+	// Right now this code is never reached. Need a way to trigger it...
+	println("Disconnecting TCP...")
+	conn.Close()
+}
+
+func message(msg string) {
+	println(msg, "\r")
+}

examples/rtl8720dn/tcpclient/wioterminal.go

@@ -0,0 +1,72 @@
+//go:build wioterminal
+// +build wioterminal
+
+package main
+
+import (
+	"device/sam"
+	"machine"
+	"runtime/interrupt"
+	"time"
+
+	"tinygo.org/x/drivers/rtl8720dn"
+)
+
+var (
+	uart UARTx
+)
+
+func handleInterrupt(interrupt.Interrupt) {
+	// should reset IRQ
+	uart.Receive(byte((uart.Bus.DATA.Get() & 0xFF)))
+	uart.Bus.INTFLAG.SetBits(sam.SERCOM_USART_INT_INTFLAG_RXC)
+}
+
+func setupRTL8720DN() (*rtl8720dn.RTL8720DN, error) {
+	machine.RTL8720D_CHIP_PU.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	machine.RTL8720D_CHIP_PU.Low()
+	time.Sleep(100 * time.Millisecond)
+	machine.RTL8720D_CHIP_PU.High()
+	time.Sleep(1000 * time.Millisecond)
+	waitSerial()
+
+	uart = UARTx{
+		UART: &machine.UART{
+			Buffer: machine.NewRingBuffer(),
+			Bus:    sam.SERCOM0_USART_INT,
+			SERCOM: 0,
+		},
+	}
+
+	uart.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, handleInterrupt)
+	uart.Configure(machine.UARTConfig{TX: machine.PB24, RX: machine.PC24, BaudRate: 614400})
+
+	rtl := rtl8720dn.New(uart)
+	rtl.Debug(debug)
+
+	_, err := rtl.Rpc_tcpip_adapter_init()
+	if err != nil {
+		return nil, err
+	}
+
+	return rtl, nil
+}
+
+// Wait for user to open serial console
+func waitSerial() {
+	for !machine.Serial.DTR() {
+		time.Sleep(100 * time.Millisecond)
+	}
+}
+
+type UARTx struct {
+	*machine.UART
+}
+
+func (u UARTx) Read(p []byte) (n int, err error) {
+	if u.Buffered() == 0 {
+		time.Sleep(1 * time.Millisecond)
+		return 0, nil
+	}
+	return u.UART.Read(p)
+}

examples/rtl8720dn/tlsclient/main.go

@@ -0,0 +1,137 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"strings"
+	"time"
+
+	"tinygo.org/x/drivers/net"
+	"tinygo.org/x/drivers/net/http"
+	"tinygo.org/x/drivers/rtl8720dn"
+)
+
+// You can override the setting with the init() in another source code.
+// func init() {
+//    ssid = "your-ssid"
+//    password = "your-password"
+//    debug = true
+//    url = "https://www.example.com"
+//    test_root_ca = "..."
+// }
+
+var (
+	ssid     string
+	password string
+	url      string = "https://www.example.com"
+	debug           = false
+)
+
+// Set the test_root_ca created by the following command
+// $ openssl s_client -showcerts -verify 5 -connect www.example.com:443 < /dev/null
+var test_root_ca = `-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
+`
+
+var buf [0x1000]byte
+
+var lastRequestTime time.Time
+var conn net.Conn
+var adaptor *rtl8720dn.RTL8720DN
+
+func main() {
+	err := run()
+	for err != nil {
+		fmt.Printf("error: %s\r\n", err.Error())
+		time.Sleep(5 * time.Second)
+	}
+}
+
+func run() error {
+	rtl, err := setupRTL8720DN()
+	if err != nil {
+		return err
+	}
+	rtl.SetRootCA(&test_root_ca)
+	net.UseDriver(rtl)
+	http.SetBuf(buf[:])
+
+	err = rtl.ConnectToAP(ssid, password)
+	if err != nil {
+		return err
+	}
+
+	ip, subnet, gateway, err := rtl.GetIP()
+	if err != nil {
+		return err
+	}
+	fmt.Printf("IP Address : %s\r\n", ip)
+	fmt.Printf("Mask       : %s\r\n", subnet)
+	fmt.Printf("Gateway    : %s\r\n", gateway)
+
+	// You can send and receive cookies in the following way
+	// 	import "tinygo.org/x/drivers/net/http/cookiejar"
+	// 	jar, err := cookiejar.New(nil)
+	// 	if err != nil {
+	// 		return err
+	// 	}
+	// 	client := &http.Client{Jar: jar}
+	// 	http.DefaultClient = client
+
+	cnt := 0
+	for {
+		// Various examples are as follows
+		//
+		// -- Get
+		// 	resp, err := http.Get(url)
+		//
+		// -- Post
+		// 	body := `cnt=12`
+		// 	resp, err = http.Post(url, "application/x-www-form-urlencoded", strings.NewReader(body))
+		//
+		// -- Post with JSON
+		// 	body := `{"msg": "hello"}`
+		// 	resp, err := http.Post(url, "application/json", strings.NewReader(body))
+
+		resp, err := http.Get(url)
+		if err != nil {
+			return err
+		}
+
+		fmt.Printf("%s %s\r\n", resp.Proto, resp.Status)
+		for k, v := range resp.Header {
+			fmt.Printf("%s: %s\r\n", k, strings.Join(v, " "))
+		}
+		fmt.Printf("\r\n")
+
+		scanner := bufio.NewScanner(resp.Body)
+		for scanner.Scan() {
+			fmt.Printf("%s\r\n", scanner.Text())
+		}
+		resp.Body.Close()
+
+		cnt++
+		fmt.Printf("-------- %d --------\r\n", cnt)
+		time.Sleep(10 * time.Second)
+	}
+}

examples/rtl8720dn/tlsclient/wioterminal.go

@@ -0,0 +1,72 @@
+//go:build wioterminal
+// +build wioterminal
+
+package main
+
+import (
+	"device/sam"
+	"machine"
+	"runtime/interrupt"
+	"time"
+
+	"tinygo.org/x/drivers/rtl8720dn"
+)
+
+var (
+	uart UARTx
+)
+
+func handleInterrupt(interrupt.Interrupt) {
+	// should reset IRQ
+	uart.Receive(byte((uart.Bus.DATA.Get() & 0xFF)))
+	uart.Bus.INTFLAG.SetBits(sam.SERCOM_USART_INT_INTFLAG_RXC)
+}
+
+func setupRTL8720DN() (*rtl8720dn.RTL8720DN, error) {
+	machine.RTL8720D_CHIP_PU.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	machine.RTL8720D_CHIP_PU.Low()
+	time.Sleep(100 * time.Millisecond)
+	machine.RTL8720D_CHIP_PU.High()
+	time.Sleep(1000 * time.Millisecond)
+	waitSerial()
+
+	uart = UARTx{
+		UART: &machine.UART{
+			Buffer: machine.NewRingBuffer(),
+			Bus:    sam.SERCOM0_USART_INT,
+			SERCOM: 0,
+		},
+	}
+
+	uart.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, handleInterrupt)
+	uart.Configure(machine.UARTConfig{TX: machine.PB24, RX: machine.PC24, BaudRate: 614400})
+
+	rtl := rtl8720dn.New(uart)
+	rtl.Debug(debug)
+
+	_, err := rtl.Rpc_tcpip_adapter_init()
+	if err != nil {
+		return nil, err
+	}
+
+	return rtl, nil
+}
+
+// Wait for user to open serial console
+func waitSerial() {
+	for !machine.Serial.DTR() {
+		time.Sleep(100 * time.Millisecond)
+	}
+}
+
+type UARTx struct {
+	*machine.UART
+}
+
+func (u UARTx) Read(p []byte) (n int, err error) {
+	if u.Buffered() == 0 {
+		time.Sleep(1 * time.Millisecond)
+		return 0, nil
+	}
+	return u.UART.Read(p)
+}

examples/rtl8720dn/udpstation/main.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"time"
+
+	"tinygo.org/x/drivers/net"
+	"tinygo.org/x/drivers/net/http"
+)
+
+// IP address of the server aka "hub". Replace with your own info.
+// You can override the setting with the init() in another source code.
+// func init() {
+//    ssid = "your-ssid"
+//    password = "your-password"
+//    hubIP = "192.168.1.118"
+//    debug = true
+// }
+
+var (
+	ssid     string
+	password string
+	hubIP    = ""
+	debug    = false
+)
+
+var buf [0x400]byte
+
+func main() {
+	err := run()
+	for err != nil {
+		fmt.Printf("error: %s\r\n", err.Error())
+		time.Sleep(5 * time.Second)
+	}
+}
+
+func run() error {
+	rtl, err := setupRTL8720DN()
+	if err != nil {
+		return err
+	}
+	net.UseDriver(rtl)
+	http.SetBuf(buf[:])
+
+	err = rtl.ConnectToAP(ssid, password)
+	if err != nil {
+		return err
+	}
+
+	ip, subnet, gateway, err := rtl.GetIP()
+	if err != nil {
+		return err
+	}
+	fmt.Printf("IP Address : %s\r\n", ip)
+	fmt.Printf("Mask       : %s\r\n", subnet)
+	fmt.Printf("Gateway    : %s\r\n", gateway)
+
+	// now make UDP connection
+	hip := net.ParseIP(hubIP)
+	raddr := &net.UDPAddr{IP: hip, Port: 2222}
+	laddr := &net.UDPAddr{Port: 2222}
+
+	println("Dialing UDP connection...")
+	conn, err := net.DialUDP("udp", laddr, raddr)
+	if err != nil {
+		return err
+	}
+
+	for {
+		// send data
+		println("Sending data...")
+		for i := 0; i < 25; i++ {
+			conn.Write([]byte("hello " + strconv.Itoa(i) + "\r\n"))
+		}
+		time.Sleep(1000 * time.Millisecond)
+	}
+
+	// Right now this code is never reached. Need a way to trigger it...
+	println("Disconnecting UDP...")
+	conn.Close()
+	println("Done.")
+
+	return nil
+}
+
+func message(msg string) {
+	println(msg, "\r")
+}

examples/rtl8720dn/udpstation/wioterminal.go

@@ -0,0 +1,72 @@
+//go:build wioterminal
+// +build wioterminal
+
+package main
+
+import (
+	"device/sam"
+	"machine"
+	"runtime/interrupt"
+	"time"
+
+	"tinygo.org/x/drivers/rtl8720dn"
+)
+
+var (
+	uart UARTx
+)
+
+func handleInterrupt(interrupt.Interrupt) {
+	// should reset IRQ
+	uart.Receive(byte((uart.Bus.DATA.Get() & 0xFF)))
+	uart.Bus.INTFLAG.SetBits(sam.SERCOM_USART_INT_INTFLAG_RXC)
+}
+
+func setupRTL8720DN() (*rtl8720dn.RTL8720DN, error) {
+	machine.RTL8720D_CHIP_PU.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	machine.RTL8720D_CHIP_PU.Low()
+	time.Sleep(100 * time.Millisecond)
+	machine.RTL8720D_CHIP_PU.High()
+	time.Sleep(1000 * time.Millisecond)
+	waitSerial()
+
+	uart = UARTx{
+		UART: &machine.UART{
+			Buffer: machine.NewRingBuffer(),
+			Bus:    sam.SERCOM0_USART_INT,
+			SERCOM: 0,
+		},
+	}
+
+	uart.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, handleInterrupt)
+	uart.Configure(machine.UARTConfig{TX: machine.PB24, RX: machine.PC24, BaudRate: 614400})
+
+	rtl := rtl8720dn.New(uart)
+	rtl.Debug(debug)
+
+	_, err := rtl.Rpc_tcpip_adapter_init()
+	if err != nil {
+		return nil, err
+	}
+
+	return rtl, nil
+}
+
+// Wait for user to open serial console
+func waitSerial() {
+	for !machine.Serial.DTR() {
+		time.Sleep(100 * time.Millisecond)
+	}
+}
+
+type UARTx struct {
+	*machine.UART
+}
+
+func (u UARTx) Read(p []byte) (n int, err error) {
+	if u.Buffered() == 0 {
+		time.Sleep(1 * time.Millisecond)
+		return 0, nil
+	}
+	return u.UART.Read(p)
+}

examples/rtl8720dn/webclient-tinyterm/main.go

@@ -0,0 +1,136 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"image/color"
+	"strings"
+	"time"
+
+	"tinygo.org/x/drivers/net"
+	"tinygo.org/x/drivers/net/http"
+	"tinygo.org/x/tinyfont/proggy"
+	"tinygo.org/x/tinyterm"
+)
+
+// You can override the setting with the init() in another source code.
+// If debug is enabled, a serial connection is required.
+// func init() {
+//    ssid = "your-ssid"
+//    password = "your-password"
+//    debug = false // true
+//    server = "tinygo.org"
+// }
+
+var (
+	ssid     string
+	password string
+	url      = "http://tinygo.org/"
+	debug    = false
+)
+
+var (
+	terminal = tinyterm.NewTerminal(display)
+
+	black = color.RGBA{0, 0, 0, 255}
+	white = color.RGBA{255, 255, 255, 255}
+	red   = color.RGBA{255, 0, 0, 255}
+	blue  = color.RGBA{0, 0, 255, 255}
+	green = color.RGBA{0, 255, 0, 255}
+
+	font = &proggy.TinySZ8pt7b
+)
+
+var buf [0x400]byte
+
+func main() {
+	display.FillScreen(black)
+	backlight.High()
+
+	terminal.Configure(&tinyterm.Config{
+		Font:       font,
+		FontHeight: 10,
+		FontOffset: 6,
+	})
+
+	err := run()
+	for err != nil {
+		fmt.Fprintf(terminal, "error: %s\r\n", err.Error())
+		time.Sleep(5 * time.Second)
+	}
+}
+
+func run() error {
+	fmt.Fprintf(terminal, "setupRTL8720DN()\r\n")
+	if debug {
+		fmt.Fprintf(terminal, "Running in debug mode.\r\n")
+		fmt.Fprintf(terminal, "A serial connection is required to continue execution.\r\n")
+	}
+	rtl, err := setupRTL8720DN()
+	if err != nil {
+		return err
+	}
+	net.UseDriver(rtl)
+	http.SetBuf(buf[:])
+
+	fmt.Fprintf(terminal, "ConnectToAP()\r\n")
+	err = rtl.ConnectToAP(ssid, password)
+	if err != nil {
+		return err
+	}
+	fmt.Fprintf(terminal, "connected\r\n\r\n")
+
+	ip, subnet, gateway, err := rtl.GetIP()
+	if err != nil {
+		return err
+	}
+	fmt.Fprintf(terminal, "IP Address : %s\r\n", ip)
+	fmt.Fprintf(terminal, "Mask       : %s\r\n", subnet)
+	fmt.Fprintf(terminal, "Gateway    : %s\r\n", gateway)
+
+	// You can send and receive cookies in the following way
+	// 	import "tinygo.org/x/drivers/net/http/cookiejar"
+	// 	jar, err := cookiejar.New(nil)
+	// 	if err != nil {
+	// 		return err
+	// 	}
+	// 	client := &http.Client{Jar: jar}
+	// 	http.DefaultClient = client
+
+	cnt := 0
+	for {
+		// Various examples are as follows
+		//
+		// -- Get
+		// 	resp, err := http.Get(url)
+		//
+		// -- Post
+		// 	body := `cnt=12`
+		// 	resp, err = http.Post(url, "application/x-www-form-urlencoded", strings.NewReader(body))
+		//
+		// -- Post with JSON
+		// 	body := `{"msg": "hello"}`
+		// 	resp, err := http.Post(url, "application/json", strings.NewReader(body))
+
+		resp, err := http.Get(url)
+		if err != nil {
+			return err
+		}
+
+		fmt.Fprintf(terminal, "%s %s\r\n", resp.Proto, resp.Status)
+		for k, v := range resp.Header {
+			fmt.Fprintf(terminal, "%s: %s\r\n", k, strings.Join(v, " "))
+		}
+		fmt.Printf("\r\n")
+
+		scanner := bufio.NewScanner(resp.Body)
+		for scanner.Scan() {
+			fmt.Fprintf(terminal, "%s\r\n", scanner.Text())
+		}
+		resp.Body.Close()
+
+		cnt++
+		fmt.Fprintf(terminal, "-------- %d --------\r\n", cnt)
+		time.Sleep(10 * time.Second)
+	}
+}

examples/rtl8720dn/webclient-tinyterm/wioterminal.go

@@ -0,0 +1,98 @@
+//go:build wioterminal
+// +build wioterminal
+
+package main
+
+import (
+	"device/sam"
+	"machine"
+	"runtime/interrupt"
+	"time"
+
+	"tinygo.org/x/drivers/ili9341"
+	"tinygo.org/x/drivers/rtl8720dn"
+)
+
+var (
+	uart UARTx
+)
+
+var (
+	display = ili9341.NewSPI(
+		machine.SPI3,
+		machine.LCD_DC,
+		machine.LCD_SS_PIN,
+		machine.LCD_RESET,
+	)
+
+	backlight = machine.LCD_BACKLIGHT
+)
+
+func init() {
+	machine.SPI3.Configure(machine.SPIConfig{
+		SCK:       machine.LCD_SCK_PIN,
+		SDO:       machine.LCD_SDO_PIN,
+		SDI:       machine.LCD_SDI_PIN,
+		Frequency: 40000000,
+	})
+	display.Configure(ili9341.Config{})
+
+	backlight.Configure(machine.PinConfig{machine.PinOutput})
+}
+
+func handleInterrupt(interrupt.Interrupt) {
+	// should reset IRQ
+	uart.Receive(byte((uart.Bus.DATA.Get() & 0xFF)))
+	uart.Bus.INTFLAG.SetBits(sam.SERCOM_USART_INT_INTFLAG_RXC)
+}
+
+func setupRTL8720DN() (*rtl8720dn.RTL8720DN, error) {
+	machine.RTL8720D_CHIP_PU.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	machine.RTL8720D_CHIP_PU.Low()
+	time.Sleep(100 * time.Millisecond)
+	machine.RTL8720D_CHIP_PU.High()
+	time.Sleep(1000 * time.Millisecond)
+	if debug {
+		waitSerial()
+	}
+
+	uart = UARTx{
+		UART: &machine.UART{
+			Buffer: machine.NewRingBuffer(),
+			Bus:    sam.SERCOM0_USART_INT,
+			SERCOM: 0,
+		},
+	}
+
+	uart.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, handleInterrupt)
+	uart.Configure(machine.UARTConfig{TX: machine.PB24, RX: machine.PC24, BaudRate: 614400})
+
+	rtl := rtl8720dn.New(uart)
+	rtl.Debug(debug)
+
+	_, err := rtl.Rpc_tcpip_adapter_init()
+	if err != nil {
+		return nil, err
+	}
+
+	return rtl, nil
+}
+
+// Wait for user to open serial console
+func waitSerial() {
+	for !machine.Serial.DTR() {
+		time.Sleep(100 * time.Millisecond)
+	}
+}
+
+type UARTx struct {
+	*machine.UART
+}
+
+func (u UARTx) Read(p []byte) (n int, err error) {
+	if u.Buffered() == 0 {
+		time.Sleep(1 * time.Millisecond)
+		return 0, nil
+	}
+	return u.UART.Read(p)
+}

examples/rtl8720dn/webclient/main.go

@@ -0,0 +1,104 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"strings"
+	"time"
+
+	"tinygo.org/x/drivers/net"
+	"tinygo.org/x/drivers/net/http"
+)
+
+// You can override the setting with the init() in another source code.
+// func init() {
+//    ssid = "your-ssid"
+//    password = "your-password"
+//    url = "http://tinygo.org/"
+//    debug = true
+// }
+
+var (
+	ssid     string
+	password string
+	url      = "http://tinygo.org/"
+	debug    = false
+)
+
+var buf [0x400]byte
+
+func main() {
+	err := run()
+	for err != nil {
+		fmt.Printf("error: %s\r\n", err.Error())
+		time.Sleep(5 * time.Second)
+	}
+}
+
+func run() error {
+	rtl, err := setupRTL8720DN()
+	if err != nil {
+		return err
+	}
+	net.UseDriver(rtl)
+	http.SetBuf(buf[:])
+
+	err = rtl.ConnectToAP(ssid, password)
+	if err != nil {
+		return err
+	}
+
+	ip, subnet, gateway, err := rtl.GetIP()
+	if err != nil {
+		return err
+	}
+	fmt.Printf("IP Address : %s\r\n", ip)
+	fmt.Printf("Mask       : %s\r\n", subnet)
+	fmt.Printf("Gateway    : %s\r\n", gateway)
+
+	// You can send and receive cookies in the following way
+	// 	import "tinygo.org/x/drivers/net/http/cookiejar"
+	// 	jar, err := cookiejar.New(nil)
+	// 	if err != nil {
+	// 		return err
+	// 	}
+	// 	client := &http.Client{Jar: jar}
+	// 	http.DefaultClient = client
+
+	cnt := 0
+	for {
+		// Various examples are as follows
+		//
+		// -- Get
+		// 	resp, err := http.Get(url)
+		//
+		// -- Post
+		// 	body := `cnt=12`
+		// 	resp, err = http.Post(url, "application/x-www-form-urlencoded", strings.NewReader(body))
+		//
+		// -- Post with JSON
+		// 	body := `{"msg": "hello"}`
+		// 	resp, err := http.Post(url, "application/json", strings.NewReader(body))
+
+		resp, err := http.Get(url)
+		if err != nil {
+			return err
+		}
+
+		fmt.Printf("%s %s\r\n", resp.Proto, resp.Status)
+		for k, v := range resp.Header {
+			fmt.Printf("%s: %s\r\n", k, strings.Join(v, " "))
+		}
+		fmt.Printf("\r\n")
+
+		scanner := bufio.NewScanner(resp.Body)
+		for scanner.Scan() {
+			fmt.Printf("%s\r\n", scanner.Text())
+		}
+		resp.Body.Close()
+
+		cnt++
+		fmt.Printf("-------- %d --------\r\n", cnt)
+		time.Sleep(10 * time.Second)
+	}
+}

examples/rtl8720dn/webclient/wioterminal.go

@@ -0,0 +1,72 @@
+//go:build wioterminal
+// +build wioterminal
+
+package main
+
+import (
+	"device/sam"
+	"machine"
+	"runtime/interrupt"
+	"time"
+
+	"tinygo.org/x/drivers/rtl8720dn"
+)
+
+var (
+	uart UARTx
+)
+
+func handleInterrupt(interrupt.Interrupt) {
+	// should reset IRQ
+	uart.Receive(byte((uart.Bus.DATA.Get() & 0xFF)))
+	uart.Bus.INTFLAG.SetBits(sam.SERCOM_USART_INT_INTFLAG_RXC)
+}
+
+func setupRTL8720DN() (*rtl8720dn.RTL8720DN, error) {
+	machine.RTL8720D_CHIP_PU.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	machine.RTL8720D_CHIP_PU.Low()
+	time.Sleep(100 * time.Millisecond)
+	machine.RTL8720D_CHIP_PU.High()
+	time.Sleep(1000 * time.Millisecond)
+	waitSerial()
+
+	uart = UARTx{
+		UART: &machine.UART{
+			Buffer: machine.NewRingBuffer(),
+			Bus:    sam.SERCOM0_USART_INT,
+			SERCOM: 0,
+		},
+	}
+
+	uart.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, handleInterrupt)
+	uart.Configure(machine.UARTConfig{TX: machine.PB24, RX: machine.PC24, BaudRate: 614400})
+
+	rtl := rtl8720dn.New(uart)
+	rtl.Debug(debug)
+
+	_, err := rtl.Rpc_tcpip_adapter_init()
+	if err != nil {
+		return nil, err
+	}
+
+	return rtl, nil
+}
+
+// Wait for user to open serial console
+func waitSerial() {
+	for !machine.Serial.DTR() {
+		time.Sleep(100 * time.Millisecond)
+	}
+}
+
+type UARTx struct {
+	*machine.UART
+}
+
+func (u UARTx) Read(p []byte) (n int, err error) {
+	if u.Buffered() == 0 {
+		time.Sleep(1 * time.Millisecond)
+		return 0, nil
+	}
+	return u.UART.Read(p)
+}

examples/rtl8720dn/webserver/main.go

@@ -0,0 +1,192 @@
+package main
+
+import (
+	"fmt"
+	"machine"
+	"strconv"
+	"time"
+
+	"tinygo.org/x/drivers/net/http"
+)
+
+// You can override the setting with the init() in another source code.
+// func init() {
+//    ssid = "your-ssid"
+//    password = "your-password"
+//    debug = true
+// }
+
+var (
+	ssid     string
+	password string
+	debug    = false
+)
+
+var led = machine.LED
+var backlight = machine.LCD_BACKLIGHT
+
+func main() {
+	led.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	backlight.Configure(machine.PinConfig{Mode: machine.PinOutput})
+
+	err := run()
+	for err != nil {
+		fmt.Printf("error: %s\r\n", err.Error())
+		time.Sleep(5 * time.Second)
+	}
+}
+
+func run() error {
+	rtl, err := setupRTL8720DN()
+	if err != nil {
+		return err
+	}
+	http.UseDriver(rtl)
+
+	err = rtl.ConnectToAP(ssid, password)
+	if err != nil {
+		return err
+	}
+
+	ip, subnet, gateway, err := rtl.GetIP()
+	if err != nil {
+		return err
+	}
+	fmt.Printf("IP Address : %s\r\n", ip)
+	fmt.Printf("Mask       : %s\r\n", subnet)
+	fmt.Printf("Gateway    : %s\r\n", gateway)
+
+	http.HandleFunc("/", root)
+	http.HandleFunc("/hello", hello)
+	http.HandleFunc("/cnt", cnt)
+	http.HandleFunc("/6", sixlines)
+	http.HandleFunc("/off", LED_OFF)
+	http.HandleFunc("/on", LED_ON)
+	if err := http.ListenAndServe(":80", nil); err != nil {
+		message(err.Error())
+	}
+	return nil
+}
+
+func root(w http.ResponseWriter, r *http.Request) {
+	access := 1
+
+	cookie, err := r.Cookie("access")
+	if err != nil {
+		if err == http.ErrNoCookie {
+			cookie = &http.Cookie{
+				Name:  "access",
+				Value: "1",
+			}
+		} else {
+			http.Error(w, fmt.Sprintf("%s", err.Error()), http.StatusBadRequest)
+			return
+		}
+	} else {
+		v, err := strconv.ParseInt(cookie.Value, 10, 0)
+		if err != nil {
+			http.Error(w, fmt.Sprintf("invalid cookie.Value : %s", cookie.Value), http.StatusBadRequest)
+			return
+		}
+		cookie.Value = fmt.Sprintf("%d", v+1)
+		access = int(v) + 1
+	}
+	http.SetCookie(w, cookie)
+	w.WriteHeader(http.StatusOK)
+
+	fmt.Fprintf(w, `
+<html>
+<head>
+    <title>TinyGo HTTP Server</title>
+    <script language="javascript" type="text/javascript">
+        var counter = 0
+        function ledOn() { fetch("/on").then(response => response.text()).then(text => { led.innerHTML = "<p>on</p>"; }); }
+        function ledOff() { fetch("/off").then(response => response.text()).then(text => { led.innerHTML = "<p>off</p>"; }); }
+        function fetchCnt() { fetch("/cnt").then(response => response.json()).then(json => { counter = json.cnt; cnt.innerHTML = counter; }); }
+        function incrCnt() { counter = counter + 1; fetch("/cnt?cnt=" + counter, { method: 'POST' }).then(response => response.json()).then(json => { counter = json.cnt; cnt.innerHTML = counter; }); }
+        function setCnt() { fetch("/cnt", {
+            method: "POST",
+            body: "cnt=" + document.getElementsByName("cnt")[0].value,
+            headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
+        }).then(response => response.json()).then(json => { counter = json.cnt; cnt.innerHTML = counter; }); return false; }
+        function onLoad() { fetchCnt(); }
+    </script>
+</head>
+<body onLoad="onLoad()">
+    <h5>TinyGo HTTP Server</h5>
+
+    <p>
+        access: %d
+    </p>
+
+    <a href="/hello">/hello</a><br>
+    <a href="/6">/6</a><br>
+
+    <p>
+        LED<br>
+        <a href="javascript:ledOn();">/on</a><br>
+        <a href="javascript:ledOff();">/off</a><br>
+    </p>
+
+
+    <p>
+        <a href="/cnt">/cnt</a><br>
+        cnt: <span id="cnt"></span><br>
+        <a href="javascript:incrCnt()">incrCnt()</a><br>
+        <form id="form1" style="display: inline" onSubmit="return setCnt()">
+        <input type="text" name="cnt">
+        <input type="button" value="set cnt", onClick="setCnt()">
+        </form>
+    </p>
+</body>
+</html>
+    `, access)
+}
+
+func sixlines(w http.ResponseWriter, r *http.Request) {
+	// https://fukuno.jig.jp/3267
+	fmt.Fprint(w, `<body onload='onkeydown=e=>K=parseInt(e.key[5]||6,28)/3-8;Z=X=[B=A=12];Y=_=>`+
+		`{for(C=[q=c=i=4];f=i--*K;c-=!Z[h+(K+6?p+K:C[i]=p*A-(p/9|0)*145)])p=B[i];for(c?0:K+6?h+=K:B=C;`+
+		`i=K=q--;f+=Z[A+p])X[p=h+B[q]]=1;h+=A;if(f|B)for(Z=X,X=[l=228],B=[[-7,-20,6,h=17,-9,3,3][t=++t%7]-4,0,1,t-6?-A:2];l--;)`+
+		`for(l%A?l-=l%A*!Z[l]:(P++,c=l+=A);--c>A;)Z[c]=Z[c-A];for(S="";i<240;S+=X[i]|(X[i]=Z[i]|=++i%A<2|i>228)?i%A?"■":"■<br>":"　");`+
+		`D.innerHTML=S+P;setTimeout(Y,i-P)};Y(h=K=t=P=0)'id=D>`)
+}
+
+func LED_ON(w http.ResponseWriter, r *http.Request) {
+	led.High()
+	backlight.High()
+	w.Header().Set(`Content-Type`, `text/plain; charset=UTF-8`)
+	fmt.Fprintf(w, "led.High()")
+}
+
+func LED_OFF(w http.ResponseWriter, r *http.Request) {
+	led.Low()
+	backlight.Low()
+	w.Header().Set(`Content-Type`, `text/plain; charset=UTF-8`)
+	fmt.Fprintf(w, "led.Low()")
+}
+
+func hello(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set(`Content-Type`, `text/plain; charset=UTF-8`)
+	fmt.Fprintf(w, "hello")
+}
+
+var counter int
+
+func cnt(w http.ResponseWriter, r *http.Request) {
+	r.ParseForm()
+	if r.Method == "POST" {
+		c := r.Form.Get("cnt")
+		if c != "" {
+			i64, _ := strconv.ParseInt(c, 0, 0)
+			counter = int(i64)
+		}
+	}
+
+	w.Header().Set(`Content-Type`, `application/json`)
+	fmt.Fprintf(w, `{"cnt": %d}`, counter)
+}
+
+func message(msg string) {
+	println(msg, "\r")
+}

examples/rtl8720dn/webserver/wioterminal.go

@@ -0,0 +1,74 @@
+//go:build wioterminal
+// +build wioterminal
+
+package main
+
+import (
+	"device/sam"
+	"machine"
+	"runtime/interrupt"
+	"time"
+
+	"tinygo.org/x/drivers/rtl8720dn"
+)
+
+var (
+	uart UARTx
+)
+
+func handleInterrupt(interrupt.Interrupt) {
+	// should reset IRQ
+	uart.Receive(byte((uart.Bus.DATA.Get() & 0xFF)))
+	uart.Bus.INTFLAG.SetBits(sam.SERCOM_USART_INT_INTFLAG_RXC)
+}
+
+func setupRTL8720DN() (*rtl8720dn.RTL8720DN, error) {
+	machine.RTL8720D_CHIP_PU.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	machine.RTL8720D_CHIP_PU.Low()
+	time.Sleep(100 * time.Millisecond)
+	machine.RTL8720D_CHIP_PU.High()
+	time.Sleep(1000 * time.Millisecond)
+	if debug {
+		waitSerial()
+	}
+
+	uart = UARTx{
+		UART: &machine.UART{
+			Buffer: machine.NewRingBuffer(),
+			Bus:    sam.SERCOM0_USART_INT,
+			SERCOM: 0,
+		},
+	}
+
+	uart.Interrupt = interrupt.New(sam.IRQ_SERCOM0_2, handleInterrupt)
+	uart.Configure(machine.UARTConfig{TX: machine.PB24, RX: machine.PC24, BaudRate: 614400})
+
+	rtl := rtl8720dn.New(uart)
+	rtl.Debug(debug)
+
+	_, err := rtl.Rpc_tcpip_adapter_init()
+	if err != nil {
+		return nil, err
+	}
+
+	return rtl, nil
+}
+
+// Wait for user to open serial console
+func waitSerial() {
+	for !machine.Serial.DTR() {
+		time.Sleep(100 * time.Millisecond)
+	}
+}
+
+type UARTx struct {
+	*machine.UART
+}
+
+func (u UARTx) Read(p []byte) (n int, err error) {
+	if u.Buffered() == 0 {
+		time.Sleep(1 * time.Millisecond)
+		return 0, nil
+	}
+	return u.UART.Read(p)
+}

examples/sdcard/console/console.go

@@ -0,0 +1,363 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"machine"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+
+	"tinygo.org/x/drivers/sdcard"
+)
+
+const consoleBufLen = 64
+const storageBufLen = 1024
+
+var (
+	debug = false
+
+	input [consoleBufLen]byte
+	store [storageBufLen]byte
+
+	console = machine.Serial
+
+	dev *sdcard.Device
+
+	commands map[string]cmdfunc = map[string]cmdfunc{
+		"":      cmdfunc(noop),
+		"help":  cmdfunc(help),
+		"dbg":   cmdfunc(dbg),
+		"erase": cmdfunc(erase),
+		"lsblk": cmdfunc(lsblk),
+		"write": cmdfunc(write),
+		"xxd":   cmdfunc(xxd),
+	}
+
+	his history
+)
+
+type history struct {
+	buf [32]string
+	wp  int
+	idx int
+}
+
+func (h *history) Add(cmd string) {
+	if len(cmd) == 0 {
+		h.idx = h.wp
+		return
+	}
+
+	if h.wp == len(h.buf)-1 {
+		for i := 1; i < len(h.buf); i++ {
+			h.buf[i-1] = h.buf[i]
+		}
+		h.wp--
+	}
+
+	h.buf[h.wp] = cmd
+	h.wp++
+	h.idx = h.wp
+}
+
+func (h *history) PeekPrev() string {
+	if h.idx > 0 {
+		h.idx--
+	}
+	return h.buf[h.idx]
+}
+
+func (h *history) PeekNext() string {
+	if h.idx < h.wp {
+		h.idx++
+	}
+	return h.buf[h.idx]
+}
+
+type cmdfunc func(argv []string)
+
+const (
+	StateInput = iota
+	StateEscape
+	StateEscBrc
+	StateCSI
+)
+
+func RunFor(device *sdcard.Device) {
+
+	dev = device
+
+	prompt()
+
+	var state = StateInput
+
+	for i := 0; ; {
+		if console.Buffered() > 0 {
+			data, _ := console.ReadByte()
+			if debug {
+				fmt.Printf("\rdata: %x, his.idx: %d\r\n\r", data, his.idx)
+				prompt()
+				console.Write(input[:i])
+			}
+			switch state {
+			case StateInput:
+				switch data {
+				case 0x8:
+					fallthrough
+				case 0x7f: // this is probably wrong... works on my machine tho :)
+					// backspace
+					if i > 0 {
+						i -= 1
+						console.Write([]byte{0x8, 0x20, 0x8})
+					}
+				case 13:
+					// return key
+					console.Write([]byte("\r\n"))
+					runCommand(string(input[:i]))
+					his.Add(string(input[:i]))
+					prompt()
+
+					i = 0
+					continue
+				case 27:
+					// escape
+					state = StateEscape
+				default:
+					// anything else, just echo the character if it is printable
+					if strconv.IsPrint(rune(data)) {
+						if i < (consoleBufLen - 1) {
+							console.WriteByte(data)
+							input[i] = data
+							i++
+						}
+					}
+				}
+			case StateEscape:
+				switch data {
+				case 0x5b:
+					state = StateEscBrc
+				default:
+					state = StateInput
+				}
+			case StateEscBrc:
+				switch data {
+				case 0x41:
+					// up
+					println()
+					prompt()
+					cmd := his.PeekPrev()
+					i = len(cmd)
+					copy(input[:i], []byte(cmd))
+					console.Write(input[:i])
+					state = StateInput
+				case 0x42:
+					//down
+					println()
+					prompt()
+					cmd := his.PeekNext()
+					i = len(cmd)
+					copy(input[:i], []byte(cmd))
+					console.Write(input[:i])
+					state = StateInput
+				default:
+					// TODO: handle escape sequences
+					state = StateInput
+				}
+			default:
+				// TODO: handle escape sequences
+				state = StateInput
+			}
+		} else {
+			time.Sleep(1 * time.Millisecond)
+		}
+	}
+}
+
+func runCommand(line string) {
+	argv := strings.SplitN(strings.TrimSpace(line), " ", -1)
+	cmd := argv[0]
+
+	cmdfn, ok := commands[cmd]
+	if !ok {
+		println("unknown command: " + line)
+		return
+	}
+	cmdfn(argv)
+}
+
+func noop(argv []string) {}
+
+func help(argv []string) {
+	fmt.Printf("help\r\n")
+	fmt.Printf("dbg\r\n")
+	fmt.Printf("erase\r\n")
+	fmt.Printf("lsblk\r\n")
+	fmt.Printf("write <hex offset> <bytes>\r\n")
+	fmt.Printf("xxd <start address> <length>\r\n")
+}
+
+func dbg(argv []string) {
+	if debug {
+		debug = false
+		println("Console debbuging off")
+	} else {
+		debug = true
+		println("Console debbuging on")
+	}
+}
+
+func lsblk(argv []string) {
+	csd := dev.CSD
+	sectors, err := csd.Sectors()
+	if err != nil {
+		fmt.Printf("%s\r\n", err.Error())
+		return
+	}
+	cid := dev.CID
+
+	fmt.Printf(
+		"\r\n-------------------------------------\r\n"+
+			" Device Information:  \r\n"+
+			"-------------------------------------\r\n"+
+			" JEDEC ID: %v\r\n"+
+			" Serial:   %v\r\n"+
+			" Status 1: %02x\r\n"+
+			" Status 2: %02x\r\n"+
+			" \r\n"+
+			" Max clock speed (MHz): %d\r\n"+
+			" Has Sector Protection: %t\r\n"+
+			" Supports Fast Reads:   %t\r\n"+
+			" Supports QSPI Reads:   %t\r\n"+
+			" Supports QSPI Write:   %t\r\n"+
+			" Write Status Split:    %t\r\n"+
+			" Single Status Byte:    %t\r\n"+
+			"-Sectors:               %d\r\n"+
+			"-Bytes (Sectors * 512)  %d\r\n"+
+			"-ManufacturerID         %02X\r\n"+
+			"-OEMApplicationID       %04X\r\n"+
+			"-ProductName            %s\r\n"+
+			"-ProductVersion         %s\r\n"+
+			"-ProductSerialNumber    %08X\r\n"+
+			"-ManufacturingYear      %02X\r\n"+
+			"-ManufacturingMonth     %02X\r\n"+
+			"-Always1                %d\r\n"+
+			"-CRC                    %02X\r\n"+
+			"-------------------------------------\r\n\r\n",
+		"attrs.JedecID",         // attrs.JedecID,
+		cid.ProductSerialNumber, // serialNumber1,
+		0,                       // status1,
+		0,                       // status2,
+		csd.TRAN_SPEED,          // attrs.MaxClockSpeedMHz,
+		false,                   // attrs.HasSectorProtection,
+		false,                   // attrs.SupportsFastRead,
+		false,                   // attrs.SupportsQSPI,
+		false,                   // attrs.SupportsQSPIWrites,
+		false,                   // attrs.WriteStatusSplit,
+		false,                   // attrs.SingleStatusByte,
+		sectors,
+		csd.Size(),
+		cid.ManufacturerID,
+		cid.OEMApplicationID,
+		cid.ProductName,
+		cid.ProductVersion,
+		cid.ProductSerialNumber,
+		cid.ManufacturingYear,
+		cid.ManufacturingMonth,
+		cid.Always1,
+		cid.CRC,
+	)
+}
+
+func erase(argv []string) {
+	fmt.Printf("erase - not impl\r\n")
+}
+
+var writeBuf [256]byte
+
+func write(argv []string) {
+	if len(argv) < 3 {
+		println("usage: write <hex offset> <bytes>")
+		return
+	}
+	var err error
+	var addr uint64 = 0x0
+	if addr, err = strconv.ParseUint(argv[1], 16, 32); err != nil {
+		println("Invalid address: " + err.Error() + "\r\n")
+		return
+	}
+	buf := writeBuf[:0]
+	for i := 0; i < len(argv[2]); i += 2 {
+		var b uint64
+		if b, err = strconv.ParseUint(argv[2][i:i+2], 16, 8); err != nil {
+			println("Invalid bytes: " + err.Error() + "\r\n")
+			return
+		}
+		buf = append(buf, byte(b))
+	}
+
+	if _, err = dev.WriteAt(buf, int64(addr)); err != nil {
+		println("Write error: " + err.Error() + "\r\n")
+	}
+}
+
+func xxd(argv []string) {
+	var err error
+	var addr uint64 = 0x0
+	var size int = 64
+	switch len(argv) {
+	case 3:
+		if size, err = strconv.Atoi(argv[2]); err != nil {
+			println("Invalid size argument: " + err.Error() + "\r\n")
+			return
+		}
+		if size > storageBufLen || size < 1 {
+			fmt.Printf("Size of hexdump must be greater than 0 and less than %d\r\n", storageBufLen)
+			return
+		}
+		fallthrough
+	case 2:
+		if addr, err = strconv.ParseUint(argv[1], 16, 32); err != nil {
+			println("Invalid address: " + err.Error() + "\r\n")
+			return
+		}
+		fallthrough
+	case 1:
+		// no args supplied, so nothing to do here, just use the defaults
+	default:
+		println("usage: xxd <hex address, ex: 0xA0> <size of hexdump in bytes>\r\n")
+		return
+	}
+	buf := store[0:size]
+	_, err = dev.ReadAt(buf, int64(addr))
+	if err != nil {
+		fmt.Printf("xxd err : %s\r\n", err.Error())
+	}
+	xxdfprint(os.Stdout, uint32(addr), buf)
+}
+
+func xxdfprint(w io.Writer, offset uint32, b []byte) {
+	var l int
+	var buf16 = make([]byte, 16)
+	for i, c := 0, len(b); i < c; i += 16 {
+		l = i + 16
+		if l >= c {
+			l = c
+		}
+		fmt.Fprintf(w, "%08x: % x    ", offset+uint32(i), b[i:l])
+		for j, n := 0, l-i; j < 16; j++ {
+			if j >= n || !strconv.IsPrint(rune(b[i+j])) || b[i+j] >= 0x80 {
+				buf16[j] = '.'
+			} else {
+				buf16[j] = b[i+j]
+			}
+		}
+		console.Write(buf16)
+		println()
+	}
+}
+
+func prompt() {
+	print("==> ")
+}

examples/sdcard/console/feather-m4.go

@@ -0,0 +1,18 @@
+//go:build feather_m4 || feather_m4_can || feather_nrf52840
+// +build feather_m4 feather_m4_can feather_nrf52840
+
+package main
+
+import (
+	"machine"
+)
+
+func init() {
+	spi = machine.SPI0
+	sckPin = machine.SPI0_SCK_PIN
+	sdoPin = machine.SPI0_SDO_PIN
+	sdiPin = machine.SPI0_SDI_PIN
+	csPin = machine.D10
+
+	ledPin = machine.LED
+}

examples/sdcard/console/grandcentral-m4.go

@@ -0,0 +1,18 @@
+//go:build grandcentral_m4
+// +build grandcentral_m4
+
+package main
+
+import (
+	"machine"
+)
+
+func init() {
+	spi = machine.SPI1
+	sckPin = machine.SDCARD_SCK_PIN
+	sdoPin = machine.SDCARD_SDO_PIN
+	sdiPin = machine.SDCARD_SDI_PIN
+	csPin = machine.SDCARD_CS_PIN
+
+	ledPin = machine.LED
+}

examples/sdcard/console/m0.go

@@ -0,0 +1,18 @@
+//go:build atsamd21 && !p1am_100
+// +build atsamd21,!p1am_100
+
+package main
+
+import (
+	"machine"
+)
+
+func init() {
+	spi = machine.SPI0
+	sckPin = machine.SPI0_SCK_PIN
+	sdoPin = machine.SPI0_SDO_PIN
+	sdiPin = machine.SPI0_SDI_PIN
+	csPin = machine.D2
+
+	ledPin = machine.LED
+}

examples/sdcard/console/main.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"fmt"
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/sdcard"
+)
+
+var (
+	spi    machine.SPI
+	sckPin machine.Pin
+	sdoPin machine.Pin
+	sdiPin machine.Pin
+	csPin  machine.Pin
+	ledPin machine.Pin
+)
+
+func main() {
+	waitSerial()
+	fmt.Printf("sdcard console\r\n")
+
+	led := ledPin
+	led.Configure(machine.PinConfig{Mode: machine.PinOutput})
+
+	sd := sdcard.New(spi, sckPin, sdoPin, sdiPin, csPin)
+	err := sd.Configure()
+	if err != nil {
+		fmt.Printf("%s\r\n", err.Error())
+		for {
+			time.Sleep(time.Hour)
+		}
+	}
+
+	go RunFor(&sd)
+
+	for {
+		led.High()
+		time.Sleep(200 * time.Millisecond)
+		led.Low()
+		time.Sleep(200 * time.Millisecond)
+	}
+}
+
+// Wait for user to open serial console
+func waitSerial() {
+	for !machine.Serial.DTR() {
+		time.Sleep(100 * time.Millisecond)
+	}
+}

examples/sdcard/console/p1am-100.go

@@ -0,0 +1,18 @@
+//go:build p1am_100
+// +build p1am_100
+
+package main
+
+import (
+	"machine"
+)
+
+func init() {
+	spi = machine.SDCARD_SPI
+	sckPin = machine.SDCARD_SCK_PIN
+	sdoPin = machine.SDCARD_SDO_PIN
+	sdiPin = machine.SDCARD_SDI_PIN
+	csPin = machine.SDCARD_SS_PIN
+
+	ledPin = machine.LED
+}

examples/sdcard/console/pygamer.go

@@ -0,0 +1,18 @@
+//go:build pygamer
+// +build pygamer
+
+package main
+
+import (
+	"machine"
+)
+
+func init() {
+	spi = machine.SPI0
+	sckPin = machine.SPI0_SCK_PIN
+	sdoPin = machine.SPI0_SDO_PIN
+	sdiPin = machine.SPI0_SDI_PIN
+	csPin = machine.D4
+
+	ledPin = machine.LED
+}

examples/sdcard/console/pyportal.go

@@ -0,0 +1,18 @@
+//go:build pyportal
+// +build pyportal
+
+package main
+
+import (
+	"machine"
+)
+
+func init() {
+	spi = machine.SPI0
+	sckPin = machine.SPI0_SCK_PIN
+	sdoPin = machine.SPI0_SDO_PIN
+	sdiPin = machine.SPI0_SDI_PIN
+	csPin = machine.D32 // SD_CS
+
+	ledPin = machine.LED
+}

examples/sdcard/console/wioterminal.go

@@ -0,0 +1,18 @@
+//go:build wioterminal
+// +build wioterminal
+
+package main
+
+import (
+	"machine"
+)
+
+func init() {
+	spi = machine.SPI2
+	sckPin = machine.SCK2
+	sdoPin = machine.SDO2
+	sdiPin = machine.SDI2
+	csPin = machine.SS2
+
+	ledPin = machine.LED
+}

examples/sdcard/tinyfs/console/console.go

@@ -0,0 +1,543 @@
+//go:build tinygo
+// +build tinygo
+
+package console
+
+import (
+	"fmt"
+	"io"
+	"machine"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+
+	"tinygo.org/x/tinyfs"
+)
+
+const consoleBufLen = 64
+
+const startBlock = 0
+const blockCount = 0
+
+var (
+	debug = false
+
+	input [consoleBufLen]byte
+
+	console  = machine.Serial
+	readyLED = machine.LED
+
+	flashdev tinyfs.BlockDevice
+	fs       tinyfs.Filesystem
+
+	currdir = "/"
+
+	commands = map[string]cmdfunc{
+		"":        noop,
+		"dbg":     dbg,
+		"help":    help,
+		"lsblk":   lsblk,
+		"mount":   mount,
+		"umount":  umount,
+		"format":  format,
+		"xxd":     xxd,
+		"ls":      ls,
+		"samples": samples,
+		"mkdir":   mkdir,
+		"cat":     cat,
+		"create":  create,
+		"write":   write,
+		"rm":      rm,
+	}
+)
+
+type cmdfunc func(argv []string)
+
+const (
+	StateInput = iota
+	StateEscape
+	StateEscBrc
+	StateCSI
+)
+
+func RunFor(dev tinyfs.BlockDevice, filesys tinyfs.Filesystem) {
+	flashdev = dev
+	fs = filesys
+
+	readyLED.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	readyLED.High()
+
+	readyLED.Low()
+	println("SPI Configured. Reading flash info")
+
+	/*
+		lfsConfig := flashlfs.NewConfig()
+		if blockCount == 0 {
+			lfsConfig.BlockCount = (flashdev.Attrs().TotalSize / lfsConfig.BlockSize) - startBlock
+		} else {
+			lfsConfig.BlockCount = blockCount
+		}
+		println("Start block:", startBlock)
+		println("Block count:", lfsConfig.BlockCount)
+
+		blockdev = flashlfs.NewBlockDevice(flashdev, startBlock, lfsConfig.BlockSize)
+	*/
+
+	prompt()
+
+	var state = StateInput
+
+	for i := 0; ; {
+		if console.Buffered() > 0 {
+			data, _ := console.ReadByte()
+			if debug {
+				fmt.Printf("\rdata: %x\r\n\r", data)
+				prompt()
+				console.Write(input[:i])
+			}
+			switch state {
+			case StateInput:
+				switch data {
+				case 0x8:
+					fallthrough
+				case 0x7f: // this is probably wrong... works on my machine tho :)
+					// backspace
+					if i > 0 {
+						i -= 1
+						console.Write([]byte{0x8, 0x20, 0x8})
+					}
+				case 13:
+					// return key
+					if console.Buffered() > 0 {
+						data, _ := console.ReadByte()
+						if data != 10 {
+							println("\r\nunexpected: \r", int(data))
+						}
+					}
+					console.Write([]byte("\r\n"))
+					runCommand(string(input[:i]))
+					prompt()
+
+					i = 0
+					continue
+				case 27:
+					// escape
+					state = StateEscape
+				default:
+					// anything else, just echo the character if it is printable
+					if strconv.IsPrint(rune(data)) {
+						if i < (consoleBufLen - 1) {
+							console.WriteByte(data)
+							input[i] = data
+							i++
+						}
+					}
+				}
+			case StateEscape:
+				switch data {
+				case 0x5b:
+					state = StateEscBrc
+				default:
+					state = StateInput
+				}
+			default:
+				// TODO: handle escape sequences
+				state = StateInput
+			}
+		}
+	}
+}
+
+func runCommand(line string) {
+	argv := strings.SplitN(strings.TrimSpace(line), " ", -1)
+	cmd := argv[0]
+	cmdfn, ok := commands[cmd]
+	if !ok {
+		println("unknown command: " + line)
+		return
+	}
+	cmdfn(argv)
+}
+
+func noop(argv []string) {}
+
+func help(argv []string) {
+	fmt.Printf("help\r\n")
+	fmt.Printf("  show help\r\n")
+	fmt.Printf("dbg\r\n")
+	fmt.Printf("  toggle debug mode\r\n")
+	fmt.Printf("xxd <hex address, ex: 0xA0> <size of hexdump in bytes>\r\n")
+	fmt.Printf("  hexdump the specified address\r\n")
+	fmt.Printf("ls <target file>\r\n")
+	fmt.Printf("  list information\r\n")
+	fmt.Printf("samples\r\n")
+	fmt.Printf("  write some files in the root directory\r\n")
+	fmt.Printf("mkdir <target dir>\r\n")
+	fmt.Printf("  create directory\r\n")
+	fmt.Printf("cat <target file>\r\n")
+	fmt.Printf("  print the contents of file\r\n")
+	fmt.Printf("create <target file>\r\n")
+	fmt.Printf("  create file\r\n")
+	fmt.Printf("write <target file>\r\n")
+	fmt.Printf("  write to file (press CTRL-D to exit)\r\n")
+	fmt.Printf("rm\r\n")
+}
+
+func dbg(argv []string) {
+	if debug {
+		debug = false
+		println("Console debugging off")
+	} else {
+		debug = true
+		println("Console debugging on")
+	}
+}
+
+func lsblk(argv []string) {
+	fmt.Printf("lsblk : not implement\r\n")
+}
+
+func mount(argv []string) {
+	if err := fs.Mount(); err != nil {
+		println("Could not mount LittleFS filesystem: " + err.Error() + "\r\n")
+	} else {
+		println("Successfully mounted LittleFS filesystem.\r\n")
+	}
+}
+
+func format(argv []string) {
+	if err := fs.Format(); err != nil {
+		println("Could not format LittleFS filesystem: " + err.Error() + "\r\n")
+	} else {
+		println("Successfully formatted LittleFS filesystem.\r\n")
+	}
+}
+
+func umount(argv []string) {
+	if err := fs.Unmount(); err != nil {
+		println("Could not unmount LittleFS filesystem: " + err.Error() + "\r\n")
+	} else {
+		println("Successfully unmounted LittleFS filesystem.\r\n")
+	}
+}
+
+/*
+	var err error
+	if fatfs == nil {
+		fatfs, err = fat.New(fatdisk)
+		if err != nil {
+			fatfs = nil
+			println("could not load FAT filesystem: " + err.Error() + "\r\n")
+		}
+		fmt.Printf("loaded fs\r\n")
+	}
+	if rootdir == nil {
+		rootdir, err = fatfs.RootDir()
+		if err != nil {
+			rootdir = nil
+			println("could not load rootdir: " + err.Error() + "\r\n")
+		}
+		fmt.Printf("loaded rootdir\r\n")
+	}
+	if currdir == nil {
+		currdir = rootdir
+	}
+*/
+
+func ls(argv []string) {
+	path := "/"
+	if len(argv) > 1 {
+		path = strings.TrimSpace(argv[1])
+	}
+	dir, err := fs.Open(path)
+	if err != nil {
+		fmt.Printf("Could not open directory %s: %v\r\n", path, err)
+		return
+	}
+	defer dir.Close()
+	infos, err := dir.Readdir(0)
+	_ = infos
+	if err != nil {
+		fmt.Printf("Could not read directory %s: %v\r\n", path, err)
+		return
+	}
+	for _, info := range infos {
+		s := "-rwxrwxrwx"
+		if info.IsDir() {
+			s = "drwxrwxrwx"
+		}
+		fmt.Printf("%s %5d %s\r\n", s, info.Size(), info.Name())
+	}
+}
+
+func mkdir(argv []string) {
+	tgt := ""
+	if len(argv) == 2 {
+		tgt = strings.TrimSpace(argv[1])
+	}
+	if debug {
+		println("Trying mkdir to " + tgt)
+	}
+	if tgt == "" {
+		println("Usage: mkdir <target dir>")
+		return
+	}
+	err := fs.Mkdir(tgt, 0777)
+	if err != nil {
+		println("Could not mkdir " + tgt + ": " + err.Error())
+	}
+}
+
+func rm(argv []string) {
+	tgt := ""
+	if len(argv) == 2 {
+		tgt = strings.TrimSpace(argv[1])
+	}
+	if debug {
+		println("Trying rm to " + tgt)
+	}
+	if tgt == "" {
+		println("Usage: rm <target dir>")
+		return
+	}
+	err := fs.Remove(tgt)
+	if err != nil {
+		println("Could not rm " + tgt + ": " + err.Error())
+	}
+}
+
+func samples(argv []string) {
+	buf := make([]byte, 90)
+	for i := 0; i < 5; i++ {
+		name := fmt.Sprintf("file%d.txt", i)
+		if bytes, err := createSampleFile(name, buf); err != nil {
+			fmt.Printf("%s\r\n", err)
+			return
+		} else {
+			fmt.Printf("wrote %d bytes to %s\r\n", bytes, name)
+		}
+	}
+}
+
+func create(argv []string) {
+	tgt := ""
+	if len(argv) == 2 {
+		tgt = strings.TrimSpace(argv[1])
+	}
+	if debug {
+		println("Trying create to " + tgt)
+	}
+	buf := make([]byte, 90)
+	if bytes, err := createSampleFile(tgt, buf); err != nil {
+		fmt.Printf("%s\r\n", err)
+		return
+	} else {
+		fmt.Printf("wrote %d bytes to %s\r\n", bytes, tgt)
+	}
+}
+
+func write(argv []string) {
+	tgt := ""
+	if len(argv) == 2 {
+		tgt = strings.TrimSpace(argv[1])
+	}
+	if debug {
+		println("Trying receive to " + tgt)
+	}
+	buf := make([]byte, 1)
+	f, err := fs.OpenFile(tgt, os.O_CREATE|os.O_WRONLY|os.O_TRUNC)
+	if err != nil {
+		fmt.Printf("error opening %s: %s\r\n", tgt, err.Error())
+		return
+	}
+	defer f.Close()
+	var n int
+	for {
+		if console.Buffered() > 0 {
+			data, _ := console.ReadByte()
+			switch data {
+			case 0x04:
+				fmt.Printf("wrote %d bytes to %s\r\n", n, tgt)
+				return
+			default:
+				// anything else, just echo the character if it is printable
+				if strconv.IsPrint(rune(data)) {
+					console.WriteByte(data)
+				}
+				buf[0] = data
+				if _, err := f.Write(buf); err != nil {
+					fmt.Printf("\nerror writing: %s\r\n", err)
+					return
+				}
+				n++
+			}
+		}
+	}
+}
+
+func createSampleFile(name string, buf []byte) (int, error) {
+	for j := uint8(0); j < uint8(len(buf)); j++ {
+		buf[j] = 0x20 + j
+	}
+	f, err := fs.OpenFile(name, os.O_CREATE|os.O_WRONLY|os.O_TRUNC)
+	if err != nil {
+		return 0, fmt.Errorf("error opening %s: %s", name, err.Error())
+	}
+	defer f.Close()
+	bytes, err := f.Write(buf)
+	if err != nil {
+		return 0, fmt.Errorf("error writing %s: %s", name, err.Error())
+	}
+	return bytes, nil
+}
+
+/*
+func cd(argv []string) {
+
+	if fatfs == nil || rootdir == nil {
+		mnt(nil)
+	}
+	if len(argv) == 1 {
+		currdir = rootdir
+		return
+	}
+	tgt := ""
+	if len(argv) == 2 {
+		tgt = strings.TrimSpace(argv[1])
+	}
+	if debug {
+		println("Trying to cd to " + tgt)
+	}
+	if tgt == "" {
+		println("Usage: cd <target dir>")
+		return
+	}
+	if debug {
+		println("Getting entry")
+	}
+	entry := currdir.Entry(tgt)
+	if entry == nil {
+		println("File not found: " + tgt)
+		return
+	}
+	if !entry.IsDir() {
+		println("Not a directory: " + tgt)
+		return
+	}
+	if debug {
+		println("Getting dir")
+	}
+	cd, err := entry.Dir()
+	if err != nil {
+		println("Could not cd to " + tgt + ": " + err.Error())
+	}
+	currdir = cd
+}
+*/
+
+func cat(argv []string) {
+	tgt := ""
+	if len(argv) == 2 {
+		tgt = strings.TrimSpace(argv[1])
+	}
+	if debug {
+		println("Trying to cat to " + tgt)
+	}
+	if tgt == "" {
+		println("Usage: cat <target file>")
+		return
+	}
+	if debug {
+		println("Getting entry")
+	}
+	f, err := fs.Open(tgt)
+	if err != nil {
+		println("Could not open: " + err.Error())
+		return
+	}
+	defer f.Close()
+	if f.IsDir() {
+		println("Not a file: " + tgt)
+		return
+	}
+	off := 0x0
+	buf := make([]byte, 64)
+	for {
+		n, err := f.Read(buf)
+		if err != nil {
+			if err == io.EOF {
+				break
+			}
+			println("Error reading " + tgt + ": " + err.Error())
+			time.Sleep(1 * time.Second)
+		}
+		xxdfprint(os.Stdout, uint32(off), buf[:n])
+		off += n
+	}
+}
+
+func xxd(argv []string) {
+	var err error
+	var addr uint64 = 0x0
+	var size int = 64
+	switch len(argv) {
+	case 3:
+		if size, err = strconv.Atoi(argv[2]); err != nil {
+			println("Invalid size argument: " + err.Error() + "\r\n")
+			return
+		}
+		if size > 512 || size < 1 {
+			fmt.Printf("Size of hexdump must be greater than 0 and less than %d\r\n", 512)
+			return
+		}
+		fallthrough
+	case 2:
+		/*
+			if argv[1][:2] != "0x" {
+				println("Invalid hex address (should start with 0x)")
+				return
+			}
+		*/
+		if addr, err = strconv.ParseUint(argv[1], 16, 32); err != nil {
+			println("Invalid address: " + err.Error() + "\r\n")
+			return
+		}
+		fallthrough
+	case 1:
+		// no args supplied, so nothing to do here, just use the defaults
+	default:
+		println("usage: xxd <hex address, ex: 0xA0> <size of hexdump in bytes>\r\n")
+		return
+	}
+	buf := make([]byte, size)
+	//bsz := uint64(flash.SectorSize)
+	//blockdev.ReadBlock(uint32(addr/bsz), uint32(addr%bsz), buf)
+	flashdev.ReadAt(buf, int64(addr))
+	xxdfprint(os.Stdout, uint32(addr), buf)
+}
+
+func xxdfprint(w io.Writer, offset uint32, b []byte) {
+	var l int
+	var buf16 = make([]byte, 16)
+	for i, c := 0, len(b); i < c; i += 16 {
+		l = i + 16
+		if l >= c {
+			l = c
+		}
+		fmt.Fprintf(w, "%08x: % x    ", offset+uint32(i), b[i:l])
+		for j, n := 0, l-i; j < 16; j++ {
+			if j >= n || !strconv.IsPrint(rune(b[i+j])) || b[i+j] >= 0x80 {
+				buf16[j] = '.'
+			} else {
+				buf16[j] = b[i+j]
+			}
+		}
+		console.Write(buf16)
+		println()
+	}
+}
+
+func prompt() {
+	print("==> ")
+}

examples/sdcard/tinyfs/feather-m4.go

@@ -0,0 +1,18 @@
+//go:build feather_m4 || feather_m4_can || feather_nrf52840
+// +build feather_m4 feather_m4_can feather_nrf52840
+
+package main
+
+import (
+	"machine"
+)
+
+func init() {
+	spi = machine.SPI0
+	sckPin = machine.SPI0_SCK_PIN
+	sdoPin = machine.SPI0_SDO_PIN
+	sdiPin = machine.SPI0_SDI_PIN
+	csPin = machine.D10
+
+	ledPin = machine.LED
+}

examples/sdcard/tinyfs/grandcentral-m4.go

@@ -0,0 +1,18 @@
+//go:build grandcentral_m4
+// +build grandcentral_m4
+
+package main
+
+import (
+	"machine"
+)
+
+func init() {
+	spi = machine.SPI1
+	sckPin = machine.SDCARD_SCK_PIN
+	sdoPin = machine.SDCARD_SDO_PIN
+	sdiPin = machine.SDCARD_SDI_PIN
+	csPin = machine.SDCARD_CS_PIN
+
+	ledPin = machine.LED
+}

examples/sdcard/tinyfs/m0.go

@@ -0,0 +1,18 @@
+//go:build atsamd21 && !p1am_100
+// +build atsamd21,!p1am_100
+
+package main
+
+import (
+	"machine"
+)
+
+func init() {
+	spi = machine.SPI0
+	sckPin = machine.SPI0_SCK_PIN
+	sdoPin = machine.SPI0_SDO_PIN
+	sdiPin = machine.SPI0_SDI_PIN
+	csPin = machine.D2
+
+	ledPin = machine.LED
+}

examples/sdcard/tinyfs/main.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"fmt"
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/examples/sdcard/tinyfs/console"
+	"tinygo.org/x/drivers/sdcard"
+	"tinygo.org/x/tinyfs/fatfs"
+)
+
+var (
+	spi    machine.SPI
+	sckPin machine.Pin
+	sdoPin machine.Pin
+	sdiPin machine.Pin
+	csPin  machine.Pin
+	ledPin machine.Pin
+)
+
+func main() {
+	waitSerial()
+
+	sd := sdcard.New(spi, sckPin, sdoPin, sdiPin, csPin)
+	err := sd.Configure()
+	if err != nil {
+		fmt.Printf("%s\r\n", err.Error())
+		for {
+			time.Sleep(time.Hour)
+		}
+	}
+
+	filesystem := fatfs.New(&sd)
+
+	// Configure FATFS with sector size (must match value in ff.h - use 512)
+	filesystem.Configure(&fatfs.Config{
+		SectorSize: 512,
+	})
+
+	console.RunFor(&sd, filesystem)
+}
+
+// Wait for user to open serial console
+func waitSerial() {
+	for !machine.Serial.DTR() {
+		time.Sleep(100 * time.Millisecond)
+	}
+}

examples/sdcard/tinyfs/p1am-100.go

@@ -0,0 +1,18 @@
+//go:build p1am_100
+// +build p1am_100
+
+package main
+
+import (
+	"machine"
+)
+
+func init() {
+	spi = machine.SDCARD_SPI
+	sckPin = machine.SDCARD_SCK_PIN
+	sdoPin = machine.SDCARD_SDO_PIN
+	sdiPin = machine.SDCARD_SDI_PIN
+	csPin = machine.SDCARD_SS_PIN
+
+	ledPin = machine.LED
+}

examples/sdcard/tinyfs/pygamer.go

@@ -0,0 +1,18 @@
+//go:build pygamer
+// +build pygamer
+
+package main
+
+import (
+	"machine"
+)
+
+func init() {
+	spi = machine.SPI0
+	sckPin = machine.SPI0_SCK_PIN
+	sdoPin = machine.SPI0_SDO_PIN
+	sdiPin = machine.SPI0_SDI_PIN
+	csPin = machine.D4
+
+	ledPin = machine.LED
+}

examples/sdcard/tinyfs/pyportal.go

@@ -0,0 +1,18 @@
+//go:build pyportal
+// +build pyportal
+
+package main
+
+import (
+	"machine"
+)
+
+func init() {
+	spi = machine.SPI0
+	sckPin = machine.SPI0_SCK_PIN
+	sdoPin = machine.SPI0_SDO_PIN
+	sdiPin = machine.SPI0_SDI_PIN
+	csPin = machine.D32 // SD_CS
+
+	ledPin = machine.LED
+}

examples/sdcard/tinyfs/wioterminal.go

@@ -0,0 +1,18 @@
+//go:build wioterminal
+// +build wioterminal
+
+package main
+
+import (
+	"machine"
+)
+
+func init() {
+	spi = machine.SPI2
+	sckPin = machine.SCK2
+	sdoPin = machine.SDO2
+	sdiPin = machine.SDI2
+	csPin = machine.SS2
+
+	ledPin = machine.LED
+}

examples/wifinina/connect/main.go

@@ -2,9 +2,8 @@
 package main
 
 import (
-	"encoding/binary"
-	"fmt"
 	"machine"
+	"strconv"
 	"time"
 
 	"tinygo.org/x/drivers/wifinina"
@@ -52,15 +51,37 @@ func main() {
 	connectToAP()
 
 	for {
-		println("---------------------------------")
+		println("----------------------------------------")
+		printSSID()
+		printRSSI()
+		printMac()
 		printIPs()
 		printTime()
-		printMacAddress()
 		time.Sleep(10 * time.Second)
 	}
 
 }
 
+func printSSID() {
+	print("SSID: ")
+	ssid, err := adaptor.GetCurrentSSID()
+	if err != nil {
+		println("Unknown (error: ", err.Error(), ")")
+		return
+	}
+	println(ssid)
+}
+
+func printRSSI() {
+	print("RSSI: ")
+	rssi, err := adaptor.GetCurrentRSSI()
+	if err != nil {
+		println("Unknown (error: ", err.Error(), ")")
+		return
+	}
+	println(strconv.Itoa(int(rssi)))
+}
+
 func printIPs() {
 	ip, subnet, gateway, err := adaptor.GetIP()
 	if err != nil {
@@ -69,39 +90,38 @@ func printIPs() {
 	}
 	println("IP: ", ip.String())
 	println("Subnet: ", subnet.String())
-	println("Gateway IP: ", gateway.String())
+	println("Gateway: ", gateway.String())
 }
 
 func printTime() {
 	print("Time: ")
 	t, err := adaptor.GetTime()
-	if err != nil {
-		println("Unknown (error: ", err.Error(), ")")
+	for {
+		if err != nil {
+			println("Unknown (error: ", err.Error(), ")")
+			return
+		}
+		if t != 0 {
+			break
+		}
+		time.Sleep(time.Second)
+		t, err = adaptor.GetTime()
 	}
 	println(time.Unix(int64(t), 0).String())
 }
 
-func printMacAddress() {
-	print("MAC Address: ")
-	b := make([]byte, 8)
+func printMac() {
+	print("MAC: ")
 	mac, err := adaptor.GetMACAddress()
 	if err != nil {
 		println("Unknown (", err.Error(), ")")
 	}
-	binary.LittleEndian.PutUint64(b, uint64(mac))
-	macAddress := ""
-	for i := 5; i >= 0; i-- {
-		macAddress += fmt.Sprintf("%0X", b[i])
-		if i != 0 {
-			macAddress += ":"
-		}
-	}
-	println(macAddress)
+	println(mac.String())
 }
 
 // Wait for user to open serial console
 func waitSerial() {
-	for !machine.UART0.DTR() {
+	for !machine.Serial.DTR() {
 		time.Sleep(100 * time.Millisecond)
 	}
 }
@@ -115,16 +135,12 @@ func connectToAP() {
 		}
 	}
 	time.Sleep(2 * time.Second)
-	message("Connecting to " + ssid)
+	println("Connecting to " + ssid)
 	adaptor.SetPassphrase(ssid, pass)
 	for st, _ := adaptor.GetConnectionStatus(); st != wifinina.StatusConnected; {
-		message("Connection status: " + st.String())
+		println("Connection status: " + st.String())
 		time.Sleep(1 * time.Second)
 		st, _ = adaptor.GetConnectionStatus()
 	}
-	message("Connected.")
-}
-
-func message(msg string) {
-	println(msg, "\r")
+	println("Connected.")
 }

examples/wifinina/http-get/main.go

@@ -0,0 +1,161 @@
+// This example opens a TCP connection using a device with WiFiNINA firmware
+// and sends a HTTP request to retrieve a webpage, based on the following
+// Arduino example:
+//
+// https://github.com/arduino-libraries/WiFiNINA/blob/master/examples/WiFiWebClientRepeating/
+//
+// This example will not work with samd21 or other systems with less than 32KB
+// of RAM.  Use the following if you want to run wifinina on samd21, etc.
+//
+// examples/wifinina/webclient
+// examples/wifinina/tlsclient
+//
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"machine"
+	"strings"
+	"time"
+
+	"tinygo.org/x/drivers/net"
+	"tinygo.org/x/drivers/net/http"
+	"tinygo.org/x/drivers/wifinina"
+)
+
+// access point info
+const ssid = ""
+const pass = ""
+
+// IP address of the server aka "hub". Replace with your own info.
+// Can specify a URL starting with http or https
+const url = "http://tinygo.org/"
+
+// these are the default pins for the Arduino Nano33 IoT.
+// change these to connect to a different UART or pins for the ESP8266/ESP32
+var (
+
+	// these are the default pins for the Arduino Nano33 IoT.
+	spi = machine.NINA_SPI
+
+	// this is the ESP chip that has the WIFININA firmware flashed on it
+	adaptor *wifinina.Device
+)
+
+var buf [0x400]byte
+
+var lastRequestTime time.Time
+var conn net.Conn
+
+func setup() {
+	// Configure SPI for 8Mhz, Mode 0, MSB First
+	spi.Configure(machine.SPIConfig{
+		Frequency: 8 * 1e6,
+		SDO:       machine.NINA_SDO,
+		SDI:       machine.NINA_SDI,
+		SCK:       machine.NINA_SCK,
+	})
+
+	adaptor = wifinina.New(spi,
+		machine.NINA_CS,
+		machine.NINA_ACK,
+		machine.NINA_GPIO0,
+		machine.NINA_RESETN)
+	adaptor.Configure()
+}
+
+func main() {
+
+	setup()
+	http.SetBuf(buf[:])
+
+	waitSerial()
+
+	connectToAP()
+
+	// You can send and receive cookies in the following way
+	// 	import "tinygo.org/x/drivers/net/http/cookiejar"
+	// 	jar, err := cookiejar.New(nil)
+	// 	if err != nil {
+	// 		return err
+	// 	}
+	// 	client := &http.Client{Jar: jar}
+	// 	http.DefaultClient = client
+
+	cnt := 0
+	for {
+		// Various examples are as follows
+		//
+		// -- Get
+		// 	resp, err := http.Get(url)
+		//
+		// -- Post
+		// 	body := `cnt=12`
+		// 	resp, err = http.Post(url, "application/x-www-form-urlencoded", strings.NewReader(body))
+		//
+		// -- Post with JSON
+		// 	body := `{"msg": "hello"}`
+		// 	resp, err := http.Post(url, "application/json", strings.NewReader(body))
+
+		resp, err := http.Get(url)
+		if err != nil {
+			fmt.Printf("%s\r\n", err.Error())
+			continue
+		}
+
+		fmt.Printf("%s %s\r\n", resp.Proto, resp.Status)
+		for k, v := range resp.Header {
+			fmt.Printf("%s: %s\r\n", k, strings.Join(v, " "))
+		}
+		fmt.Printf("\r\n")
+
+		scanner := bufio.NewScanner(resp.Body)
+		for scanner.Scan() {
+			fmt.Printf("%s\r\n", scanner.Text())
+		}
+		resp.Body.Close()
+
+		cnt++
+		fmt.Printf("-------- %d --------\r\n", cnt)
+		time.Sleep(10 * time.Second)
+	}
+
+}
+
+// Wait for user to open serial console
+func waitSerial() {
+	for !machine.Serial.DTR() {
+		time.Sleep(100 * time.Millisecond)
+	}
+}
+
+// connect to access point
+func connectToAP() {
+	if len(ssid) == 0 || len(pass) == 0 {
+		for {
+			println("Connection failed: Either ssid or password not set")
+			time.Sleep(10 * time.Second)
+		}
+	}
+	time.Sleep(2 * time.Second)
+	message("Connecting to " + ssid)
+	adaptor.SetPassphrase(ssid, pass)
+	for st, _ := adaptor.GetConnectionStatus(); st != wifinina.StatusConnected; {
+		message("Connection status: " + st.String())
+		time.Sleep(1 * time.Second)
+		st, _ = adaptor.GetConnectionStatus()
+	}
+	message("Connected.")
+	time.Sleep(2 * time.Second)
+	ip, _, _, err := adaptor.GetIP()
+	for ; err != nil; ip, _, _, err = adaptor.GetIP() {
+		message(err.Error())
+		time.Sleep(1 * time.Second)
+	}
+	message(ip.String())
+}
+
+func message(msg string) {
+	println(msg, "\r")
+}

examples/wifinina/ntpclient/main.go

@@ -92,7 +92,7 @@ func main() {
 
 // Wait for user to open serial console
 func waitSerial() {
-	for !machine.UART0.DTR() {
+	for !machine.Serial.DTR() {
 		time.Sleep(100 * time.Millisecond)
 	}
 }

examples/wifinina/tlsclient/main.go

@@ -77,7 +77,7 @@ func main() {
 
 // Wait for user to open serial console
 func waitSerial() {
-	for !machine.UART0.DTR() {
+	for !machine.Serial.DTR() {
 		time.Sleep(100 * time.Millisecond)
 	}
 }

examples/wifinina/webclient/main.go

@@ -74,7 +74,7 @@ func main() {
 
 // Wait for user to open serial console
 func waitSerial() {
-	for !machine.UART0.DTR() {
+	for !machine.Serial.DTR() {
 		time.Sleep(100 * time.Millisecond)
 	}
 }

examples/ws2812/arduino.go

@@ -1,9 +1,11 @@
+//go:build arduino
 // +build arduino
 
 package main
 
 import "machine"
 
-// Replace neo in the code below to match the pin
+// Replace neo and led in the code below to match the pin
 // that you are using if different.
 var neo = machine.D2
+var led = machine.LED

examples/ws2812/digispark.go

@@ -1,3 +1,4 @@
+//go:build digispark
 // +build digispark
 
 package main
@@ -5,6 +6,7 @@ package main
 import "machine"
 
 // This is the pin assignment for the Digispark only.
-// Replace neo in the code below to match the pin
+// Replace neo and led in the code below to match the pin
 // that you are using if different.
 var neo machine.Pin = 0
+var led = machine.LED

examples/ws2812/main.go

@@ -15,7 +15,6 @@ import (
 var leds [10]color.RGBA
 
 func main() {
-	led := machine.LED
 	led.Configure(machine.PinConfig{Mode: machine.PinOutput})
 
 	neo.Configure(machine.PinConfig{Mode: machine.PinOutput})

examples/ws2812/others.go

@@ -1,9 +1,11 @@
-// +build !digispark,!arduino
+//go:build !digispark && !arduino && !qtpy
+// +build !digispark,!arduino,!qtpy
 
 package main
 
 import "machine"
 
-// Replace neo in the code below to match the pin
+// Replace neo and led in the code below to match the pin
 // that you are using if different.
-var neo machine.Pin = machine.NEOPIXELS
+var neo machine.Pin = machine.WS2812
+var led = machine.LED

examples/ws2812/qtpy.go

@@ -0,0 +1,17 @@
+//go:build qtpy
+// +build qtpy
+
+package main
+
+import "machine"
+
+// Replace neo and led in the code below to match the pin
+// that you are using if different.
+var neo machine.Pin = machine.NEOPIXELS
+var led = machine.NoPin
+
+func init() {
+	pwr := machine.NEOPIXELS_POWER
+	pwr.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	pwr.High()
+}

flash/transport_qspi_samd.go

@@ -1,3 +1,4 @@
+//go:build atsamd51
 // +build atsamd51
 
 package flash

go.mod

@@ -5,4 +5,8 @@ go 1.15
 require (
 	github.com/eclipse/paho.mqtt.golang v1.2.0
 	github.com/frankban/quicktest v1.10.2
+	golang.org/x/net v0.0.0-20210614182718-04defd469f4e // indirect
+	tinygo.org/x/tinyfont v0.2.1
+	tinygo.org/x/tinyfs v0.1.0
+	tinygo.org/x/tinyterm v0.1.0
 )

go.sum

@@ -1,3 +1,4 @@
+github.com/bgould/http v0.0.0-20190627042742-d268792bdee7/go.mod h1:BTqvVegvwifopl4KTEDth6Zezs9eR+lCWhvGKvkxJHE=
 github.com/eclipse/paho.mqtt.golang v1.2.0 h1:1F8mhG9+aO5/xpdtFkW4SxOJB67ukuDC3t2y2qayIX0=
 github.com/eclipse/paho.mqtt.golang v1.2.0/go.mod h1:H9keYFcgq3Qr5OUJm/JZI/i6U7joQ8SYLhZwfeOo6Ts=
 github.com/frankban/quicktest v1.10.2 h1:19ARM85nVi4xH7xPXuc5eM/udya5ieh7b/Sv+d844Tk=
@@ -9,5 +10,23 @@ github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfn
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/valyala/fastjson v1.6.3/go.mod h1:CLCAqky6SMuOcxStkYQvblddUtoRxhYMGLrsQns1aXY=
+golang.org/x/net v0.0.0-20210614182718-04defd469f4e h1:XpT3nA5TvE525Ne3hInMh6+GETgn27Zfm9dxsThnX2Q=
+golang.org/x/net v0.0.0-20210614182718-04defd469f4e/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/text v0.3.6 h1:aRYxNxv6iGQlyVaZmk6ZgYEDa+Jg18DxebPSrd6bg1M=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+tinygo.org/x/drivers v0.14.0/go.mod h1:uT2svMq3EpBZpKkGO+NQHjxjGf1f42ra4OnMMwQL2aI=
+tinygo.org/x/drivers v0.15.1/go.mod h1:uT2svMq3EpBZpKkGO+NQHjxjGf1f42ra4OnMMwQL2aI=
+tinygo.org/x/drivers v0.16.0/go.mod h1:uT2svMq3EpBZpKkGO+NQHjxjGf1f42ra4OnMMwQL2aI=
+tinygo.org/x/tinyfont v0.2.1 h1:FAaemBzw8wsfhAtG6fWW+QjyWw/K8YqEeiWo4N1pv4o=
+tinygo.org/x/tinyfont v0.2.1/go.mod h1:eLqnYSrFRjt5STxWaMeOWJTzrKhXqpWw7nU3bPfKOAM=
+tinygo.org/x/tinyfs v0.1.0 h1:yx1Tq9L60rpCm6HURo45x+Tnag+O9RGSbQfgeCb6XYU=
+tinygo.org/x/tinyfs v0.1.0/go.mod h1:ysc8Y92iHfhTXeyEM9+c7zviUQ4fN9UCFgSOFfMWv20=
+tinygo.org/x/tinyterm v0.1.0 h1:80i+j+KWoxCFa/Xfp6pWbh79x+8zUdMXC1vaKj2QhkY=
+tinygo.org/x/tinyterm v0.1.0/go.mod h1:/DDhNnGwNF2/tNgHywvyZuCGnbH3ov49Z/6e8LPLRR4=

ili9341/ili9341.go

@@ -160,6 +160,20 @@ func (d *Device) DrawRGBBitmap(x, y int16, data []uint16, w, h int16) error {
 	return nil
 }
 
+// DrawRGBBitmap8 copies an RGB bitmap to the internal buffer at given coordinates
+func (d *Device) DrawRGBBitmap8(x, y int16, data []uint8, w, h int16) error {
+	k, i := d.Size()
+	if x < 0 || y < 0 || w <= 0 || h <= 0 ||
+		x >= k || (x+w) > k || y >= i || (y+h) > i {
+		return errors.New("rectangle coordinates outside display area")
+	}
+	d.setWindow(x, y, w, h)
+	d.startWrite()
+	d.driver.write8sl(data)
+	d.endWrite()
+	return nil
+}
+
 // FillRectangle fills a rectangle at given coordinates with a color
 func (d *Device) FillRectangle(x, y, width, height int16, c color.RGBA) error {
 	k, i := d.Size()
@@ -300,7 +314,9 @@ func (d *Device) sendCommand(cmd byte, data []byte) {
 	d.dc.Low()
 	d.driver.write8(cmd)
 	d.dc.High()
-	d.driver.write8sl(data)
+	if data != nil {
+		d.driver.write8sl(data)
+	}
 	d.endWrite()
 }
 

ili9341/parallel_atsamd51.go

@@ -1,3 +1,4 @@
+//go:build atsamd51
 // +build atsamd51
 
 package ili9341

ili9341/spi.go

@@ -0,0 +1,74 @@
+//go:build !atsamd51 && !atsamd21
+// +build !atsamd51,!atsamd21
+
+package ili9341
+
+import (
+	"machine"
+
+	"tinygo.org/x/drivers"
+)
+
+var buf [64]byte
+
+type spiDriver struct {
+	bus drivers.SPI
+}
+
+func NewSPI(bus drivers.SPI, dc, cs, rst machine.Pin) *Device {
+	return &Device{
+		dc:  dc,
+		cs:  cs,
+		rst: rst,
+		rd:  machine.NoPin,
+		driver: &spiDriver{
+			bus: bus,
+		},
+	}
+}
+
+func (pd *spiDriver) configure(config *Config) {
+}
+
+func (pd *spiDriver) write8(b byte) {
+	buf[0] = b
+	pd.bus.Tx(buf[:1], nil)
+}
+
+func (pd *spiDriver) write8n(b byte, n int) {
+	buf[0] = b
+	for i := 0; i < n; i++ {
+		pd.bus.Tx(buf[:1], nil)
+	}
+}
+
+func (pd *spiDriver) write8sl(b []byte) {
+	pd.bus.Tx(b, nil)
+}
+
+func (pd *spiDriver) write16(data uint16) {
+	buf[0] = uint8(data >> 8)
+	buf[1] = uint8(data)
+	pd.bus.Tx(buf[:2], nil)
+}
+
+func (pd *spiDriver) write16n(data uint16, n int) {
+	for i := 0; i < len(buf); i += 2 {
+		buf[i] = uint8(data >> 8)
+		buf[i+1] = uint8(data)
+	}
+
+	for i := 0; i < (n >> 5); i++ {
+		pd.bus.Tx(buf[:], nil)
+	}
+
+	pd.bus.Tx(buf[:n%64], nil)
+}
+
+func (pd *spiDriver) write16sl(data []uint16) {
+	for i, c := 0, len(data); i < c; i++ {
+		buf[0] = uint8(data[i] >> 8)
+		buf[1] = uint8(data[i])
+		pd.bus.Tx(buf[:2], nil)
+	}
+}

ili9341/spi_atsamd21.go

@@ -1,3 +1,4 @@
+//go:build atsamd21
 // +build atsamd21
 
 package ili9341

ili9341/spi_atsamd51.go

@@ -1,3 +1,4 @@
+//go:build atsamd51
 // +build atsamd51
 
 package ili9341

image/README.md

@@ -0,0 +1,60 @@
+# tinygo.org/x/drivers/image
+
+This is an image package that uses less RAM to run on a microcontroller.
+Unlike Go's original image package, `image.Decode()` does not return `image.Image`.
+
+Instead, a callback can be set to process the data corresponding to the image.
+
+## How to use
+
+First, use `SetCallback()` to set the callback.
+Then call `png.Decode()` or `jpeg.Decode()`.
+The callback will be called as many times as necessary to load the image.
+
+`SetCallback()` needs to be given a Buffer to handle the callback and the actual function to be called.
+The `data []uint16` in the callback is in RGB565 format.
+
+The `io.Reader` to pass to `Decode()` specifies the binary data of the image.
+
+```go
+func drawPng(display *ili9341.Device) error {
+	p := strings.NewReader(pngImage)
+	png.SetCallback(buffer[:], func(data []uint16, x, y, w, h, width, height int16) {
+		err := display.DrawRGBBitmap(x, y, data[:w*h], w, h)
+		if err != nil {
+			errorMessage(fmt.Errorf("error drawPng: %s", err))
+		}
+	})
+
+	return png.Decode(p)
+}
+```
+
+```go
+func drawJpeg(display *ili9341.Device) error {
+	p := strings.NewReader(jpegImage)
+	jpeg.SetCallback(buffer[:], func(data []uint16, x, y, w, h, width, height int16) {
+		err := display.DrawRGBBitmap(x, y, data[:w*h], w, h)
+		if err != nil {
+			errorMessage(fmt.Errorf("error drawJpeg: %s", err))
+		}
+	})
+
+	return jpeg.Decode(p)
+}
+```
+
+## How to create an image
+
+The following program will output an image binary like the one in [images.go](./examples/ili9341/slideshow/images.go).  
+
+```
+go run ./cmd/convert2bin ./path/to/png_or_jpg.png
+```
+
+## Examples
+
+An example can be found below.
+Processing jpegs requires a minimum of 32KB of RAM.
+
+* [./examples/ili9341/slideshow](./examples/ili9341/slideshow)

image/internal/compress/flate/deflate.go

@@ -0,0 +1,748 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+	"fmt"
+	"io"
+	"math"
+)
+
+const (
+	NoCompression      = 0
+	BestSpeed          = 1
+	BestCompression    = 9
+	DefaultCompression = -1
+
+	// HuffmanOnly disables Lempel-Ziv match searching and only performs Huffman
+	// entropy encoding. This mode is useful in compressing data that has
+	// already been compressed with an LZ style algorithm (e.g. Snappy or LZ4)
+	// that lacks an entropy encoder. Compression gains are achieved when
+	// certain bytes in the input stream occur more frequently than others.
+	//
+	// Note that HuffmanOnly produces a compressed output that is
+	// RFC 1951 compliant. That is, any valid DEFLATE decompressor will
+	// continue to be able to decompress this output.
+	HuffmanOnly = -2
+)
+
+const (
+	logWindowSize = 15
+	windowSize    = 1 << logWindowSize
+	windowMask    = windowSize - 1
+
+	// The LZ77 step produces a sequence of literal tokens and <length, offset>
+	// pair tokens. The offset is also known as distance. The underlying wire
+	// format limits the range of lengths and offsets. For example, there are
+	// 256 legitimate lengths: those in the range [3, 258]. This package's
+	// compressor uses a higher minimum match length, enabling optimizations
+	// such as finding matches via 32-bit loads and compares.
+	baseMatchLength = 3       // The smallest match length per the RFC section 3.2.5
+	minMatchLength  = 4       // The smallest match length that the compressor actually emits
+	maxMatchLength  = 258     // The largest match length
+	baseMatchOffset = 1       // The smallest match offset
+	maxMatchOffset  = 1 << 15 // The largest match offset
+
+	// The maximum number of tokens we put into a single flate block, just to
+	// stop things from getting too large.
+	maxFlateBlockTokens = 1 << 14
+	maxStoreBlockSize   = 65535
+	hashBits            = 17 // After 17 performance degrades
+	hashSize            = 1 << hashBits
+	hashMask            = (1 << hashBits) - 1
+	maxHashOffset       = 1 << 24
+
+	skipNever = math.MaxInt32
+)
+
+type compressionLevel struct {
+	level, good, lazy, nice, chain, fastSkipHashing int
+}
+
+var levels = []compressionLevel{
+	{0, 0, 0, 0, 0, 0}, // NoCompression.
+	{1, 0, 0, 0, 0, 0}, // BestSpeed uses a custom algorithm; see deflatefast.go.
+	// For levels 2-3 we don't bother trying with lazy matches.
+	{2, 4, 0, 16, 8, 5},
+	{3, 4, 0, 32, 32, 6},
+	// Levels 4-9 use increasingly more lazy matching
+	// and increasingly stringent conditions for "good enough".
+	{4, 4, 4, 16, 16, skipNever},
+	{5, 8, 16, 32, 32, skipNever},
+	{6, 8, 16, 128, 128, skipNever},
+	{7, 8, 32, 128, 256, skipNever},
+	{8, 32, 128, 258, 1024, skipNever},
+	{9, 32, 258, 258, 4096, skipNever},
+}
+
+type compressor struct {
+	compressionLevel
+
+	w          *huffmanBitWriter
+	bulkHasher func([]byte, []uint32)
+
+	// compression algorithm
+	fill      func(*compressor, []byte) int // copy data to window
+	step      func(*compressor)             // process window
+	sync      bool                          // requesting flush
+	bestSpeed *deflateFast                  // Encoder for BestSpeed
+
+	// Input hash chains
+	// hashHead[hashValue] contains the largest inputIndex with the specified hash value
+	// If hashHead[hashValue] is within the current window, then
+	// hashPrev[hashHead[hashValue] & windowMask] contains the previous index
+	// with the same hash value.
+	chainHead  int
+	hashHead   [hashSize]uint32
+	hashPrev   [windowSize]uint32
+	hashOffset int
+
+	// input window: unprocessed data is window[index:windowEnd]
+	index         int
+	window        []byte
+	windowEnd     int
+	blockStart    int  // window index where current tokens start
+	byteAvailable bool // if true, still need to process window[index-1].
+
+	// queued output tokens
+	tokens []token
+
+	// deflate state
+	length         int
+	offset         int
+	hash           uint32
+	maxInsertIndex int
+	err            error
+
+	// hashMatch must be able to contain hashes for the maximum match length.
+	hashMatch [maxMatchLength - 1]uint32
+}
+
+func (d *compressor) fillDeflate(b []byte) int {
+	if d.index >= 2*windowSize-(minMatchLength+maxMatchLength) {
+		// shift the window by windowSize
+		copy(d.window, d.window[windowSize:2*windowSize])
+		d.index -= windowSize
+		d.windowEnd -= windowSize
+		if d.blockStart >= windowSize {
+			d.blockStart -= windowSize
+		} else {
+			d.blockStart = math.MaxInt32
+		}
+		d.hashOffset += windowSize
+		if d.hashOffset > maxHashOffset {
+			delta := d.hashOffset - 1
+			d.hashOffset -= delta
+			d.chainHead -= delta
+
+			// Iterate over slices instead of arrays to avoid copying
+			// the entire table onto the stack (Issue #18625).
+			for i, v := range d.hashPrev[:] {
+				if int(v) > delta {
+					d.hashPrev[i] = uint32(int(v) - delta)
+				} else {
+					d.hashPrev[i] = 0
+				}
+			}
+			for i, v := range d.hashHead[:] {
+				if int(v) > delta {
+					d.hashHead[i] = uint32(int(v) - delta)
+				} else {
+					d.hashHead[i] = 0
+				}
+			}
+		}
+	}
+	n := copy(d.window[d.windowEnd:], b)
+	d.windowEnd += n
+	return n
+}
+
+func (d *compressor) writeBlock(tokens []token, index int) error {
+	if index > 0 {
+		var window []byte
+		if d.blockStart <= index {
+			window = d.window[d.blockStart:index]
+		}
+		d.blockStart = index
+		d.w.writeBlock(tokens, false, window)
+		return d.w.err
+	}
+	return nil
+}
+
+// fillWindow will fill the current window with the supplied
+// dictionary and calculate all hashes.
+// This is much faster than doing a full encode.
+// Should only be used after a reset.
+func (d *compressor) fillWindow(b []byte) {
+	// Do not fill window if we are in store-only mode.
+	if d.compressionLevel.level < 2 {
+		return
+	}
+	if d.index != 0 || d.windowEnd != 0 {
+		panic("internal error: fillWindow called with stale data")
+	}
+
+	// If we are given too much, cut it.
+	if len(b) > windowSize {
+		b = b[len(b)-windowSize:]
+	}
+	// Add all to window.
+	n := copy(d.window, b)
+
+	// Calculate 256 hashes at the time (more L1 cache hits)
+	loops := (n + 256 - minMatchLength) / 256
+	for j := 0; j < loops; j++ {
+		index := j * 256
+		end := index + 256 + minMatchLength - 1
+		if end > n {
+			end = n
+		}
+		toCheck := d.window[index:end]
+		dstSize := len(toCheck) - minMatchLength + 1
+
+		if dstSize <= 0 {
+			continue
+		}
+
+		dst := d.hashMatch[:dstSize]
+		d.bulkHasher(toCheck, dst)
+		var newH uint32
+		for i, val := range dst {
+			di := i + index
+			newH = val
+			hh := &d.hashHead[newH&hashMask]
+			// Get previous value with the same hash.
+			// Our chain should point to the previous value.
+			d.hashPrev[di&windowMask] = *hh
+			// Set the head of the hash chain to us.
+			*hh = uint32(di + d.hashOffset)
+		}
+		d.hash = newH
+	}
+	// Update window information.
+	d.windowEnd = n
+	d.index = n
+}
+
+// Try to find a match starting at index whose length is greater than prevSize.
+// We only look at chainCount possibilities before giving up.
+func (d *compressor) findMatch(pos int, prevHead int, prevLength int, lookahead int) (length, offset int, ok bool) {
+	minMatchLook := maxMatchLength
+	if lookahead < minMatchLook {
+		minMatchLook = lookahead
+	}
+
+	win := d.window[0 : pos+minMatchLook]
+
+	// We quit when we get a match that's at least nice long
+	nice := len(win) - pos
+	if d.nice < nice {
+		nice = d.nice
+	}
+
+	// If we've got a match that's good enough, only look in 1/4 the chain.
+	tries := d.chain
+	length = prevLength
+	if length >= d.good {
+		tries >>= 2
+	}
+
+	wEnd := win[pos+length]
+	wPos := win[pos:]
+	minIndex := pos - windowSize
+
+	for i := prevHead; tries > 0; tries-- {
+		if wEnd == win[i+length] {
+			n := matchLen(win[i:], wPos, minMatchLook)
+
+			if n > length && (n > minMatchLength || pos-i <= 4096) {
+				length = n
+				offset = pos - i
+				ok = true
+				if n >= nice {
+					// The match is good enough that we don't try to find a better one.
+					break
+				}
+				wEnd = win[pos+n]
+			}
+		}
+		if i == minIndex {
+			// hashPrev[i & windowMask] has already been overwritten, so stop now.
+			break
+		}
+		i = int(d.hashPrev[i&windowMask]) - d.hashOffset
+		if i < minIndex || i < 0 {
+			break
+		}
+	}
+	return
+}
+
+func (d *compressor) writeStoredBlock(buf []byte) error {
+	if d.w.writeStoredHeader(len(buf), false); d.w.err != nil {
+		return d.w.err
+	}
+	d.w.writeBytes(buf)
+	return d.w.err
+}
+
+const hashmul = 0x1e35a7bd
+
+// hash4 returns a hash representation of the first 4 bytes
+// of the supplied slice.
+// The caller must ensure that len(b) >= 4.
+func hash4(b []byte) uint32 {
+	return ((uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24) * hashmul) >> (32 - hashBits)
+}
+
+// bulkHash4 will compute hashes using the same
+// algorithm as hash4
+func bulkHash4(b []byte, dst []uint32) {
+	if len(b) < minMatchLength {
+		return
+	}
+	hb := uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
+	dst[0] = (hb * hashmul) >> (32 - hashBits)
+	end := len(b) - minMatchLength + 1
+	for i := 1; i < end; i++ {
+		hb = (hb << 8) | uint32(b[i+3])
+		dst[i] = (hb * hashmul) >> (32 - hashBits)
+	}
+}
+
+// matchLen returns the number of matching bytes in a and b
+// up to length 'max'. Both slices must be at least 'max'
+// bytes in size.
+func matchLen(a, b []byte, max int) int {
+	a = a[:max]
+	b = b[:len(a)]
+	for i, av := range a {
+		if b[i] != av {
+			return i
+		}
+	}
+	return max
+}
+
+// encSpeed will compress and store the currently added data,
+// if enough has been accumulated or we at the end of the stream.
+// Any error that occurred will be in d.err
+func (d *compressor) encSpeed() {
+	// We only compress if we have maxStoreBlockSize.
+	if d.windowEnd < maxStoreBlockSize {
+		if !d.sync {
+			return
+		}
+
+		// Handle small sizes.
+		if d.windowEnd < 128 {
+			switch {
+			case d.windowEnd == 0:
+				return
+			case d.windowEnd <= 16:
+				d.err = d.writeStoredBlock(d.window[:d.windowEnd])
+			default:
+				d.w.writeBlockHuff(false, d.window[:d.windowEnd])
+				d.err = d.w.err
+			}
+			d.windowEnd = 0
+			d.bestSpeed.reset()
+			return
+		}
+
+	}
+	// Encode the block.
+	d.tokens = d.bestSpeed.encode(d.tokens[:0], d.window[:d.windowEnd])
+
+	// If we removed less than 1/16th, Huffman compress the block.
+	if len(d.tokens) > d.windowEnd-(d.windowEnd>>4) {
+		d.w.writeBlockHuff(false, d.window[:d.windowEnd])
+	} else {
+		d.w.writeBlockDynamic(d.tokens, false, d.window[:d.windowEnd])
+	}
+	d.err = d.w.err
+	d.windowEnd = 0
+}
+
+func (d *compressor) initDeflate() {
+	d.window = make([]byte, 2*windowSize)
+	d.hashOffset = 1
+	d.tokens = make([]token, 0, maxFlateBlockTokens+1)
+	d.length = minMatchLength - 1
+	d.offset = 0
+	d.byteAvailable = false
+	d.index = 0
+	d.hash = 0
+	d.chainHead = -1
+	d.bulkHasher = bulkHash4
+}
+
+func (d *compressor) deflate() {
+	if d.windowEnd-d.index < minMatchLength+maxMatchLength && !d.sync {
+		return
+	}
+
+	d.maxInsertIndex = d.windowEnd - (minMatchLength - 1)
+	if d.index < d.maxInsertIndex {
+		d.hash = hash4(d.window[d.index : d.index+minMatchLength])
+	}
+
+Loop:
+	for {
+		if d.index > d.windowEnd {
+			panic("index > windowEnd")
+		}
+		lookahead := d.windowEnd - d.index
+		if lookahead < minMatchLength+maxMatchLength {
+			if !d.sync {
+				break Loop
+			}
+			if d.index > d.windowEnd {
+				panic("index > windowEnd")
+			}
+			if lookahead == 0 {
+				// Flush current output block if any.
+				if d.byteAvailable {
+					// There is still one pending token that needs to be flushed
+					d.tokens = append(d.tokens, literalToken(uint32(d.window[d.index-1])))
+					d.byteAvailable = false
+				}
+				if len(d.tokens) > 0 {
+					if d.err = d.writeBlock(d.tokens, d.index); d.err != nil {
+						return
+					}
+					d.tokens = d.tokens[:0]
+				}
+				break Loop
+			}
+		}
+		if d.index < d.maxInsertIndex {
+			// Update the hash
+			d.hash = hash4(d.window[d.index : d.index+minMatchLength])
+			hh := &d.hashHead[d.hash&hashMask]
+			d.chainHead = int(*hh)
+			d.hashPrev[d.index&windowMask] = uint32(d.chainHead)
+			*hh = uint32(d.index + d.hashOffset)
+		}
+		prevLength := d.length
+		prevOffset := d.offset
+		d.length = minMatchLength - 1
+		d.offset = 0
+		minIndex := d.index - windowSize
+		if minIndex < 0 {
+			minIndex = 0
+		}
+
+		if d.chainHead-d.hashOffset >= minIndex &&
+			(d.fastSkipHashing != skipNever && lookahead > minMatchLength-1 ||
+				d.fastSkipHashing == skipNever && lookahead > prevLength && prevLength < d.lazy) {
+			if newLength, newOffset, ok := d.findMatch(d.index, d.chainHead-d.hashOffset, minMatchLength-1, lookahead); ok {
+				d.length = newLength
+				d.offset = newOffset
+			}
+		}
+		if d.fastSkipHashing != skipNever && d.length >= minMatchLength ||
+			d.fastSkipHashing == skipNever && prevLength >= minMatchLength && d.length <= prevLength {
+			// There was a match at the previous step, and the current match is
+			// not better. Output the previous match.
+			if d.fastSkipHashing != skipNever {
+				d.tokens = append(d.tokens, matchToken(uint32(d.length-baseMatchLength), uint32(d.offset-baseMatchOffset)))
+			} else {
+				d.tokens = append(d.tokens, matchToken(uint32(prevLength-baseMatchLength), uint32(prevOffset-baseMatchOffset)))
+			}
+			// Insert in the hash table all strings up to the end of the match.
+			// index and index-1 are already inserted. If there is not enough
+			// lookahead, the last two strings are not inserted into the hash
+			// table.
+			if d.length <= d.fastSkipHashing {
+				var newIndex int
+				if d.fastSkipHashing != skipNever {
+					newIndex = d.index + d.length
+				} else {
+					newIndex = d.index + prevLength - 1
+				}
+				index := d.index
+				for index++; index < newIndex; index++ {
+					if index < d.maxInsertIndex {
+						d.hash = hash4(d.window[index : index+minMatchLength])
+						// Get previous value with the same hash.
+						// Our chain should point to the previous value.
+						hh := &d.hashHead[d.hash&hashMask]
+						d.hashPrev[index&windowMask] = *hh
+						// Set the head of the hash chain to us.
+						*hh = uint32(index + d.hashOffset)
+					}
+				}
+				d.index = index
+
+				if d.fastSkipHashing == skipNever {
+					d.byteAvailable = false
+					d.length = minMatchLength - 1
+				}
+			} else {
+				// For matches this long, we don't bother inserting each individual
+				// item into the table.
+				d.index += d.length
+				if d.index < d.maxInsertIndex {
+					d.hash = hash4(d.window[d.index : d.index+minMatchLength])
+				}
+			}
+			if len(d.tokens) == maxFlateBlockTokens {
+				// The block includes the current character
+				if d.err = d.writeBlock(d.tokens, d.index); d.err != nil {
+					return
+				}
+				d.tokens = d.tokens[:0]
+			}
+		} else {
+			if d.fastSkipHashing != skipNever || d.byteAvailable {
+				i := d.index - 1
+				if d.fastSkipHashing != skipNever {
+					i = d.index
+				}
+				d.tokens = append(d.tokens, literalToken(uint32(d.window[i])))
+				if len(d.tokens) == maxFlateBlockTokens {
+					if d.err = d.writeBlock(d.tokens, i+1); d.err != nil {
+						return
+					}
+					d.tokens = d.tokens[:0]
+				}
+			}
+			d.index++
+			if d.fastSkipHashing == skipNever {
+				d.byteAvailable = true
+			}
+		}
+	}
+}
+
+func (d *compressor) fillStore(b []byte) int {
+	n := copy(d.window[d.windowEnd:], b)
+	d.windowEnd += n
+	return n
+}
+
+func (d *compressor) store() {
+	if d.windowEnd > 0 && (d.windowEnd == maxStoreBlockSize || d.sync) {
+		d.err = d.writeStoredBlock(d.window[:d.windowEnd])
+		d.windowEnd = 0
+	}
+}
+
+// storeHuff compresses and stores the currently added data
+// when the d.window is full or we are at the end of the stream.
+// Any error that occurred will be in d.err
+func (d *compressor) storeHuff() {
+	if d.windowEnd < len(d.window) && !d.sync || d.windowEnd == 0 {
+		return
+	}
+	d.w.writeBlockHuff(false, d.window[:d.windowEnd])
+	d.err = d.w.err
+	d.windowEnd = 0
+}
+
+func (d *compressor) write(b []byte) (n int, err error) {
+	if d.err != nil {
+		return 0, d.err
+	}
+	n = len(b)
+	for len(b) > 0 {
+		d.step(d)
+		b = b[d.fill(d, b):]
+		if d.err != nil {
+			return 0, d.err
+		}
+	}
+	return n, nil
+}
+
+func (d *compressor) syncFlush() error {
+	if d.err != nil {
+		return d.err
+	}
+	d.sync = true
+	d.step(d)
+	if d.err == nil {
+		d.w.writeStoredHeader(0, false)
+		d.w.flush()
+		d.err = d.w.err
+	}
+	d.sync = false
+	return d.err
+}
+
+func (d *compressor) init(w io.Writer, level int) (err error) {
+	d.w = newHuffmanBitWriter(w)
+
+	switch {
+	case level == NoCompression:
+		d.window = make([]byte, maxStoreBlockSize)
+		d.fill = (*compressor).fillStore
+		d.step = (*compressor).store
+	case level == HuffmanOnly:
+		d.window = make([]byte, maxStoreBlockSize)
+		d.fill = (*compressor).fillStore
+		d.step = (*compressor).storeHuff
+	case level == BestSpeed:
+		d.compressionLevel = levels[level]
+		d.window = make([]byte, maxStoreBlockSize)
+		d.fill = (*compressor).fillStore
+		d.step = (*compressor).encSpeed
+		d.bestSpeed = newDeflateFast()
+		d.tokens = make([]token, maxStoreBlockSize)
+	case level == DefaultCompression:
+		level = 6
+		fallthrough
+	case 2 <= level && level <= 9:
+		d.compressionLevel = levels[level]
+		d.initDeflate()
+		d.fill = (*compressor).fillDeflate
+		d.step = (*compressor).deflate
+	default:
+		return fmt.Errorf("flate: invalid compression level %d: want value in range [-2, 9]", level)
+	}
+	return nil
+}
+
+func (d *compressor) reset(w io.Writer) {
+	d.w.reset(w)
+	d.sync = false
+	d.err = nil
+	switch d.compressionLevel.level {
+	case NoCompression:
+		d.windowEnd = 0
+	case BestSpeed:
+		d.windowEnd = 0
+		d.tokens = d.tokens[:0]
+		d.bestSpeed.reset()
+	default:
+		d.chainHead = -1
+		for i := range d.hashHead {
+			d.hashHead[i] = 0
+		}
+		for i := range d.hashPrev {
+			d.hashPrev[i] = 0
+		}
+		d.hashOffset = 1
+		d.index, d.windowEnd = 0, 0
+		d.blockStart, d.byteAvailable = 0, false
+		d.tokens = d.tokens[:0]
+		d.length = minMatchLength - 1
+		d.offset = 0
+		d.hash = 0
+		d.maxInsertIndex = 0
+	}
+}
+
+func (d *compressor) close() error {
+	if d.err != nil {
+		return d.err
+	}
+	d.sync = true
+	d.step(d)
+	if d.err != nil {
+		return d.err
+	}
+	if d.w.writeStoredHeader(0, true); d.w.err != nil {
+		return d.w.err
+	}
+	d.w.flush()
+	return d.w.err
+}
+
+// NewWriter returns a new Writer compressing data at the given level.
+// Following zlib, levels range from 1 (BestSpeed) to 9 (BestCompression);
+// higher levels typically run slower but compress more. Level 0
+// (NoCompression) does not attempt any compression; it only adds the
+// necessary DEFLATE framing.
+// Level -1 (DefaultCompression) uses the default compression level.
+// Level -2 (HuffmanOnly) will use Huffman compression only, giving
+// a very fast compression for all types of input, but sacrificing considerable
+// compression efficiency.
+//
+// If level is in the range [-2, 9] then the error returned will be nil.
+// Otherwise the error returned will be non-nil.
+func NewWriter(w io.Writer, level int) (*Writer, error) {
+	var dw Writer
+	if err := dw.d.init(w, level); err != nil {
+		return nil, err
+	}
+	return &dw, nil
+}
+
+// NewWriterDict is like NewWriter but initializes the new
+// Writer with a preset dictionary. The returned Writer behaves
+// as if the dictionary had been written to it without producing
+// any compressed output. The compressed data written to w
+// can only be decompressed by a Reader initialized with the
+// same dictionary.
+func NewWriterDict(w io.Writer, level int, dict []byte) (*Writer, error) {
+	dw := &dictWriter{w}
+	zw, err := NewWriter(dw, level)
+	if err != nil {
+		return nil, err
+	}
+	zw.d.fillWindow(dict)
+	zw.dict = append(zw.dict, dict...) // duplicate dictionary for Reset method.
+	return zw, err
+}
+
+type dictWriter struct {
+	w io.Writer
+}
+
+func (w *dictWriter) Write(b []byte) (n int, err error) {
+	return w.w.Write(b)
+}
+
+// A Writer takes data written to it and writes the compressed
+// form of that data to an underlying writer (see NewWriter).
+type Writer struct {
+	d    compressor
+	dict []byte
+}
+
+// Write writes data to w, which will eventually write the
+// compressed form of data to its underlying writer.
+func (w *Writer) Write(data []byte) (n int, err error) {
+	return w.d.write(data)
+}
+
+// Flush flushes any pending data to the underlying writer.
+// It is useful mainly in compressed network protocols, to ensure that
+// a remote reader has enough data to reconstruct a packet.
+// Flush does not return until the data has been written.
+// Calling Flush when there is no pending data still causes the Writer
+// to emit a sync marker of at least 4 bytes.
+// If the underlying writer returns an error, Flush returns that error.
+//
+// In the terminology of the zlib library, Flush is equivalent to Z_SYNC_FLUSH.
+func (w *Writer) Flush() error {
+	// For more about flushing:
+	// https://www.bolet.org/~pornin/deflate-flush.html
+	return w.d.syncFlush()
+}
+
+// Close flushes and closes the writer.
+func (w *Writer) Close() error {
+	return w.d.close()
+}
+
+// Reset discards the writer's state and makes it equivalent to
+// the result of NewWriter or NewWriterDict called with dst
+// and w's level and dictionary.
+func (w *Writer) Reset(dst io.Writer) {
+	if dw, ok := w.d.w.writer.(*dictWriter); ok {
+		// w was created with NewWriterDict
+		dw.w = dst
+		w.d.reset(dw)
+		w.d.fillWindow(w.dict)
+	} else {
+		// w was created with NewWriter
+		w.d.reset(dst)
+	}
+}

image/internal/compress/flate/deflate_test.go

@@ -0,0 +1,984 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"internal/testenv"
+	"io"
+	"math/rand"
+	"os"
+	"reflect"
+	"runtime/debug"
+	"sync"
+	"testing"
+)
+
+type deflateTest struct {
+	in    []byte
+	level int
+	out   []byte
+}
+
+type deflateInflateTest struct {
+	in []byte
+}
+
+type reverseBitsTest struct {
+	in       uint16
+	bitCount uint8
+	out      uint16
+}
+
+var deflateTests = []*deflateTest{
+	{[]byte{}, 0, []byte{1, 0, 0, 255, 255}},
+	{[]byte{0x11}, -1, []byte{18, 4, 4, 0, 0, 255, 255}},
+	{[]byte{0x11}, DefaultCompression, []byte{18, 4, 4, 0, 0, 255, 255}},
+	{[]byte{0x11}, 4, []byte{18, 4, 4, 0, 0, 255, 255}},
+
+	{[]byte{0x11}, 0, []byte{0, 1, 0, 254, 255, 17, 1, 0, 0, 255, 255}},
+	{[]byte{0x11, 0x12}, 0, []byte{0, 2, 0, 253, 255, 17, 18, 1, 0, 0, 255, 255}},
+	{[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}, 0,
+		[]byte{0, 8, 0, 247, 255, 17, 17, 17, 17, 17, 17, 17, 17, 1, 0, 0, 255, 255},
+	},
+	{[]byte{}, 2, []byte{1, 0, 0, 255, 255}},
+	{[]byte{0x11}, 2, []byte{18, 4, 4, 0, 0, 255, 255}},
+	{[]byte{0x11, 0x12}, 2, []byte{18, 20, 2, 4, 0, 0, 255, 255}},
+	{[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}, 2, []byte{18, 132, 2, 64, 0, 0, 0, 255, 255}},
+	{[]byte{}, 9, []byte{1, 0, 0, 255, 255}},
+	{[]byte{0x11}, 9, []byte{18, 4, 4, 0, 0, 255, 255}},
+	{[]byte{0x11, 0x12}, 9, []byte{18, 20, 2, 4, 0, 0, 255, 255}},
+	{[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}, 9, []byte{18, 132, 2, 64, 0, 0, 0, 255, 255}},
+}
+
+var deflateInflateTests = []*deflateInflateTest{
+	{[]byte{}},
+	{[]byte{0x11}},
+	{[]byte{0x11, 0x12}},
+	{[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}},
+	{[]byte{0x11, 0x10, 0x13, 0x41, 0x21, 0x21, 0x41, 0x13, 0x87, 0x78, 0x13}},
+	{largeDataChunk()},
+}
+
+var reverseBitsTests = []*reverseBitsTest{
+	{1, 1, 1},
+	{1, 2, 2},
+	{1, 3, 4},
+	{1, 4, 8},
+	{1, 5, 16},
+	{17, 5, 17},
+	{257, 9, 257},
+	{29, 5, 23},
+}
+
+func largeDataChunk() []byte {
+	result := make([]byte, 100000)
+	for i := range result {
+		result[i] = byte(i * i & 0xFF)
+	}
+	return result
+}
+
+func TestBulkHash4(t *testing.T) {
+	for _, x := range deflateTests {
+		y := x.out
+		if len(y) < minMatchLength {
+			continue
+		}
+		y = append(y, y...)
+		for j := 4; j < len(y); j++ {
+			y := y[:j]
+			dst := make([]uint32, len(y)-minMatchLength+1)
+			for i := range dst {
+				dst[i] = uint32(i + 100)
+			}
+			bulkHash4(y, dst)
+			for i, got := range dst {
+				want := hash4(y[i:])
+				if got != want && got == uint32(i)+100 {
+					t.Errorf("Len:%d Index:%d, want 0x%08x but not modified", len(y), i, want)
+				} else if got != want {
+					t.Errorf("Len:%d Index:%d, got 0x%08x want:0x%08x", len(y), i, got, want)
+				}
+			}
+		}
+	}
+}
+
+func TestDeflate(t *testing.T) {
+	for _, h := range deflateTests {
+		var buf bytes.Buffer
+		w, err := NewWriter(&buf, h.level)
+		if err != nil {
+			t.Errorf("NewWriter: %v", err)
+			continue
+		}
+		w.Write(h.in)
+		w.Close()
+		if !bytes.Equal(buf.Bytes(), h.out) {
+			t.Errorf("Deflate(%d, %x) = \n%#v, want \n%#v", h.level, h.in, buf.Bytes(), h.out)
+		}
+	}
+}
+
+// A sparseReader returns a stream consisting of 0s followed by 1<<16 1s.
+// This tests missing hash references in a very large input.
+type sparseReader struct {
+	l   int64
+	cur int64
+}
+
+func (r *sparseReader) Read(b []byte) (n int, err error) {
+	if r.cur >= r.l {
+		return 0, io.EOF
+	}
+	n = len(b)
+	cur := r.cur + int64(n)
+	if cur > r.l {
+		n -= int(cur - r.l)
+		cur = r.l
+	}
+	for i := range b[0:n] {
+		if r.cur+int64(i) >= r.l-1<<16 {
+			b[i] = 1
+		} else {
+			b[i] = 0
+		}
+	}
+	r.cur = cur
+	return
+}
+
+func TestVeryLongSparseChunk(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping sparse chunk during short test")
+	}
+	w, err := NewWriter(io.Discard, 1)
+	if err != nil {
+		t.Errorf("NewWriter: %v", err)
+		return
+	}
+	if _, err = io.Copy(w, &sparseReader{l: 23e8}); err != nil {
+		t.Errorf("Compress failed: %v", err)
+		return
+	}
+}
+
+type syncBuffer struct {
+	buf    bytes.Buffer
+	mu     sync.RWMutex
+	closed bool
+	ready  chan bool
+}
+
+func newSyncBuffer() *syncBuffer {
+	return &syncBuffer{ready: make(chan bool, 1)}
+}
+
+func (b *syncBuffer) Read(p []byte) (n int, err error) {
+	for {
+		b.mu.RLock()
+		n, err = b.buf.Read(p)
+		b.mu.RUnlock()
+		if n > 0 || b.closed {
+			return
+		}
+		<-b.ready
+	}
+}
+
+func (b *syncBuffer) signal() {
+	select {
+	case b.ready <- true:
+	default:
+	}
+}
+
+func (b *syncBuffer) Write(p []byte) (n int, err error) {
+	n, err = b.buf.Write(p)
+	b.signal()
+	return
+}
+
+func (b *syncBuffer) WriteMode() {
+	b.mu.Lock()
+}
+
+func (b *syncBuffer) ReadMode() {
+	b.mu.Unlock()
+	b.signal()
+}
+
+func (b *syncBuffer) Close() error {
+	b.closed = true
+	b.signal()
+	return nil
+}
+
+func testSync(t *testing.T, level int, input []byte, name string) {
+	if len(input) == 0 {
+		return
+	}
+
+	t.Logf("--testSync %d, %d, %s", level, len(input), name)
+	buf := newSyncBuffer()
+	buf1 := new(bytes.Buffer)
+	buf.WriteMode()
+	w, err := NewWriter(io.MultiWriter(buf, buf1), level)
+	if err != nil {
+		t.Errorf("NewWriter: %v", err)
+		return
+	}
+	r := NewReader(buf)
+
+	// Write half the input and read back.
+	for i := 0; i < 2; i++ {
+		var lo, hi int
+		if i == 0 {
+			lo, hi = 0, (len(input)+1)/2
+		} else {
+			lo, hi = (len(input)+1)/2, len(input)
+		}
+		t.Logf("#%d: write %d-%d", i, lo, hi)
+		if _, err := w.Write(input[lo:hi]); err != nil {
+			t.Errorf("testSync: write: %v", err)
+			return
+		}
+		if i == 0 {
+			if err := w.Flush(); err != nil {
+				t.Errorf("testSync: flush: %v", err)
+				return
+			}
+		} else {
+			if err := w.Close(); err != nil {
+				t.Errorf("testSync: close: %v", err)
+			}
+		}
+		buf.ReadMode()
+		out := make([]byte, hi-lo+1)
+		m, err := io.ReadAtLeast(r, out, hi-lo)
+		t.Logf("#%d: read %d", i, m)
+		if m != hi-lo || err != nil {
+			t.Errorf("testSync/%d (%d, %d, %s): read %d: %d, %v (%d left)", i, level, len(input), name, hi-lo, m, err, buf.buf.Len())
+			return
+		}
+		if !bytes.Equal(input[lo:hi], out[:hi-lo]) {
+			t.Errorf("testSync/%d: read wrong bytes: %x vs %x", i, input[lo:hi], out[:hi-lo])
+			return
+		}
+		// This test originally checked that after reading
+		// the first half of the input, there was nothing left
+		// in the read buffer (buf.buf.Len() != 0) but that is
+		// not necessarily the case: the write Flush may emit
+		// some extra framing bits that are not necessary
+		// to process to obtain the first half of the uncompressed
+		// data. The test ran correctly most of the time, because
+		// the background goroutine had usually read even
+		// those extra bits by now, but it's not a useful thing to
+		// check.
+		buf.WriteMode()
+	}
+	buf.ReadMode()
+	out := make([]byte, 10)
+	if n, err := r.Read(out); n > 0 || err != io.EOF {
+		t.Errorf("testSync (%d, %d, %s): final Read: %d, %v (hex: %x)", level, len(input), name, n, err, out[0:n])
+	}
+	if buf.buf.Len() != 0 {
+		t.Errorf("testSync (%d, %d, %s): extra data at end", level, len(input), name)
+	}
+	r.Close()
+
+	// stream should work for ordinary reader too
+	r = NewReader(buf1)
+	out, err = io.ReadAll(r)
+	if err != nil {
+		t.Errorf("testSync: read: %s", err)
+		return
+	}
+	r.Close()
+	if !bytes.Equal(input, out) {
+		t.Errorf("testSync: decompress(compress(data)) != data: level=%d input=%s", level, name)
+	}
+}
+
+func testToFromWithLevelAndLimit(t *testing.T, level int, input []byte, name string, limit int) {
+	var buffer bytes.Buffer
+	w, err := NewWriter(&buffer, level)
+	if err != nil {
+		t.Errorf("NewWriter: %v", err)
+		return
+	}
+	w.Write(input)
+	w.Close()
+	if limit > 0 && buffer.Len() > limit {
+		t.Errorf("level: %d, len(compress(data)) = %d > limit = %d", level, buffer.Len(), limit)
+		return
+	}
+	if limit > 0 {
+		t.Logf("level: %d, size:%.2f%%, %d b\n", level, float64(buffer.Len()*100)/float64(limit), buffer.Len())
+	}
+	r := NewReader(&buffer)
+	out, err := io.ReadAll(r)
+	if err != nil {
+		t.Errorf("read: %s", err)
+		return
+	}
+	r.Close()
+	if !bytes.Equal(input, out) {
+		t.Errorf("decompress(compress(data)) != data: level=%d input=%s", level, name)
+		return
+	}
+	testSync(t, level, input, name)
+}
+
+func testToFromWithLimit(t *testing.T, input []byte, name string, limit [11]int) {
+	for i := 0; i < 10; i++ {
+		testToFromWithLevelAndLimit(t, i, input, name, limit[i])
+	}
+	// Test HuffmanCompression
+	testToFromWithLevelAndLimit(t, -2, input, name, limit[10])
+}
+
+func TestDeflateInflate(t *testing.T) {
+	t.Parallel()
+	for i, h := range deflateInflateTests {
+		if testing.Short() && len(h.in) > 10000 {
+			continue
+		}
+		testToFromWithLimit(t, h.in, fmt.Sprintf("#%d", i), [11]int{})
+	}
+}
+
+func TestReverseBits(t *testing.T) {
+	for _, h := range reverseBitsTests {
+		if v := reverseBits(h.in, h.bitCount); v != h.out {
+			t.Errorf("reverseBits(%v,%v) = %v, want %v",
+				h.in, h.bitCount, v, h.out)
+		}
+	}
+}
+
+type deflateInflateStringTest struct {
+	filename string
+	label    string
+	limit    [11]int
+}
+
+var deflateInflateStringTests = []deflateInflateStringTest{
+	{
+		"../testdata/e.txt",
+		"2.718281828...",
+		[...]int{100018, 50650, 50960, 51150, 50930, 50790, 50790, 50790, 50790, 50790, 43683},
+	},
+	{
+		"../../testdata/Isaac.Newton-Opticks.txt",
+		"Isaac.Newton-Opticks",
+		[...]int{567248, 218338, 198211, 193152, 181100, 175427, 175427, 173597, 173422, 173422, 325240},
+	},
+}
+
+func TestDeflateInflateString(t *testing.T) {
+	t.Parallel()
+	if testing.Short() && testenv.Builder() == "" {
+		t.Skip("skipping in short mode")
+	}
+	for _, test := range deflateInflateStringTests {
+		gold, err := os.ReadFile(test.filename)
+		if err != nil {
+			t.Error(err)
+		}
+		testToFromWithLimit(t, gold, test.label, test.limit)
+		if testing.Short() {
+			break
+		}
+	}
+}
+
+func TestReaderDict(t *testing.T) {
+	const (
+		dict = "hello world"
+		text = "hello again world"
+	)
+	var b bytes.Buffer
+	w, err := NewWriter(&b, 5)
+	if err != nil {
+		t.Fatalf("NewWriter: %v", err)
+	}
+	w.Write([]byte(dict))
+	w.Flush()
+	b.Reset()
+	w.Write([]byte(text))
+	w.Close()
+
+	r := NewReaderDict(&b, []byte(dict))
+	data, err := io.ReadAll(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(data) != "hello again world" {
+		t.Fatalf("read returned %q want %q", string(data), text)
+	}
+}
+
+func TestWriterDict(t *testing.T) {
+	const (
+		dict = "hello world"
+		text = "hello again world"
+	)
+	var b bytes.Buffer
+	w, err := NewWriter(&b, 5)
+	if err != nil {
+		t.Fatalf("NewWriter: %v", err)
+	}
+	w.Write([]byte(dict))
+	w.Flush()
+	b.Reset()
+	w.Write([]byte(text))
+	w.Close()
+
+	var b1 bytes.Buffer
+	w, _ = NewWriterDict(&b1, 5, []byte(dict))
+	w.Write([]byte(text))
+	w.Close()
+
+	if !bytes.Equal(b1.Bytes(), b.Bytes()) {
+		t.Fatalf("writer wrote %q want %q", b1.Bytes(), b.Bytes())
+	}
+}
+
+// See https://golang.org/issue/2508
+func TestRegression2508(t *testing.T) {
+	if testing.Short() {
+		t.Logf("test disabled with -short")
+		return
+	}
+	w, err := NewWriter(io.Discard, 1)
+	if err != nil {
+		t.Fatalf("NewWriter: %v", err)
+	}
+	buf := make([]byte, 1024)
+	for i := 0; i < 131072; i++ {
+		if _, err := w.Write(buf); err != nil {
+			t.Fatalf("writer failed: %v", err)
+		}
+	}
+	w.Close()
+}
+
+func TestWriterReset(t *testing.T) {
+	t.Parallel()
+	for level := 0; level <= 9; level++ {
+		if testing.Short() && level > 1 {
+			break
+		}
+		w, err := NewWriter(io.Discard, level)
+		if err != nil {
+			t.Fatalf("NewWriter: %v", err)
+		}
+		buf := []byte("hello world")
+		n := 1024
+		if testing.Short() {
+			n = 10
+		}
+		for i := 0; i < n; i++ {
+			w.Write(buf)
+		}
+		w.Reset(io.Discard)
+
+		wref, err := NewWriter(io.Discard, level)
+		if err != nil {
+			t.Fatalf("NewWriter: %v", err)
+		}
+
+		// DeepEqual doesn't compare functions.
+		w.d.fill, wref.d.fill = nil, nil
+		w.d.step, wref.d.step = nil, nil
+		w.d.bulkHasher, wref.d.bulkHasher = nil, nil
+		w.d.bestSpeed, wref.d.bestSpeed = nil, nil
+		// hashMatch is always overwritten when used.
+		copy(w.d.hashMatch[:], wref.d.hashMatch[:])
+		if len(w.d.tokens) != 0 {
+			t.Errorf("level %d Writer not reset after Reset. %d tokens were present", level, len(w.d.tokens))
+		}
+		// As long as the length is 0, we don't care about the content.
+		w.d.tokens = wref.d.tokens
+
+		// We don't care if there are values in the window, as long as it is at d.index is 0
+		w.d.window = wref.d.window
+		if !reflect.DeepEqual(w, wref) {
+			t.Errorf("level %d Writer not reset after Reset", level)
+		}
+	}
+
+	levels := []int{0, 1, 2, 5, 9}
+	for _, level := range levels {
+		t.Run(fmt.Sprint(level), func(t *testing.T) {
+			testResetOutput(t, level, nil)
+		})
+	}
+
+	t.Run("dict", func(t *testing.T) {
+		for _, level := range levels {
+			t.Run(fmt.Sprint(level), func(t *testing.T) {
+				testResetOutput(t, level, nil)
+			})
+		}
+	})
+}
+
+func testResetOutput(t *testing.T, level int, dict []byte) {
+	writeData := func(w *Writer) {
+		msg := []byte("now is the time for all good gophers")
+		w.Write(msg)
+		w.Flush()
+
+		hello := []byte("hello world")
+		for i := 0; i < 1024; i++ {
+			w.Write(hello)
+		}
+
+		fill := bytes.Repeat([]byte("x"), 65000)
+		w.Write(fill)
+	}
+
+	buf := new(bytes.Buffer)
+	var w *Writer
+	var err error
+	if dict == nil {
+		w, err = NewWriter(buf, level)
+	} else {
+		w, err = NewWriterDict(buf, level, dict)
+	}
+	if err != nil {
+		t.Fatalf("NewWriter: %v", err)
+	}
+
+	writeData(w)
+	w.Close()
+	out1 := buf.Bytes()
+
+	buf2 := new(bytes.Buffer)
+	w.Reset(buf2)
+	writeData(w)
+	w.Close()
+	out2 := buf2.Bytes()
+
+	if len(out1) != len(out2) {
+		t.Errorf("got %d, expected %d bytes", len(out2), len(out1))
+		return
+	}
+	if !bytes.Equal(out1, out2) {
+		mm := 0
+		for i, b := range out1[:len(out2)] {
+			if b != out2[i] {
+				t.Errorf("mismatch index %d: %#02x, expected %#02x", i, out2[i], b)
+			}
+			mm++
+			if mm == 10 {
+				t.Fatal("Stopping")
+			}
+		}
+	}
+	t.Logf("got %d bytes", len(out1))
+}
+
+// TestBestSpeed tests that round-tripping through deflate and then inflate
+// recovers the original input. The Write sizes are near the thresholds in the
+// compressor.encSpeed method (0, 16, 128), as well as near maxStoreBlockSize
+// (65535).
+func TestBestSpeed(t *testing.T) {
+	t.Parallel()
+	abc := make([]byte, 128)
+	for i := range abc {
+		abc[i] = byte(i)
+	}
+	abcabc := bytes.Repeat(abc, 131072/len(abc))
+	var want []byte
+
+	testCases := [][]int{
+		{65536, 0},
+		{65536, 1},
+		{65536, 1, 256},
+		{65536, 1, 65536},
+		{65536, 14},
+		{65536, 15},
+		{65536, 16},
+		{65536, 16, 256},
+		{65536, 16, 65536},
+		{65536, 127},
+		{65536, 128},
+		{65536, 128, 256},
+		{65536, 128, 65536},
+		{65536, 129},
+		{65536, 65536, 256},
+		{65536, 65536, 65536},
+	}
+
+	for i, tc := range testCases {
+		if i >= 3 && testing.Short() {
+			break
+		}
+		for _, firstN := range []int{1, 65534, 65535, 65536, 65537, 131072} {
+			tc[0] = firstN
+		outer:
+			for _, flush := range []bool{false, true} {
+				buf := new(bytes.Buffer)
+				want = want[:0]
+
+				w, err := NewWriter(buf, BestSpeed)
+				if err != nil {
+					t.Errorf("i=%d, firstN=%d, flush=%t: NewWriter: %v", i, firstN, flush, err)
+					continue
+				}
+				for _, n := range tc {
+					want = append(want, abcabc[:n]...)
+					if _, err := w.Write(abcabc[:n]); err != nil {
+						t.Errorf("i=%d, firstN=%d, flush=%t: Write: %v", i, firstN, flush, err)
+						continue outer
+					}
+					if !flush {
+						continue
+					}
+					if err := w.Flush(); err != nil {
+						t.Errorf("i=%d, firstN=%d, flush=%t: Flush: %v", i, firstN, flush, err)
+						continue outer
+					}
+				}
+				if err := w.Close(); err != nil {
+					t.Errorf("i=%d, firstN=%d, flush=%t: Close: %v", i, firstN, flush, err)
+					continue
+				}
+
+				r := NewReader(buf)
+				got, err := io.ReadAll(r)
+				if err != nil {
+					t.Errorf("i=%d, firstN=%d, flush=%t: ReadAll: %v", i, firstN, flush, err)
+					continue
+				}
+				r.Close()
+
+				if !bytes.Equal(got, want) {
+					t.Errorf("i=%d, firstN=%d, flush=%t: corruption during deflate-then-inflate", i, firstN, flush)
+					continue
+				}
+			}
+		}
+	}
+}
+
+var errIO = errors.New("IO error")
+
+// failWriter fails with errIO exactly at the nth call to Write.
+type failWriter struct{ n int }
+
+func (w *failWriter) Write(b []byte) (int, error) {
+	w.n--
+	if w.n == -1 {
+		return 0, errIO
+	}
+	return len(b), nil
+}
+
+func TestWriterPersistentError(t *testing.T) {
+	t.Parallel()
+	d, err := os.ReadFile("../../testdata/Isaac.Newton-Opticks.txt")
+	if err != nil {
+		t.Fatalf("ReadFile: %v", err)
+	}
+	d = d[:10000] // Keep this test short
+
+	zw, err := NewWriter(nil, DefaultCompression)
+	if err != nil {
+		t.Fatalf("NewWriter: %v", err)
+	}
+
+	// Sweep over the threshold at which an error is returned.
+	// The variable i makes it such that the ith call to failWriter.Write will
+	// return errIO. Since failWriter errors are not persistent, we must ensure
+	// that flate.Writer errors are persistent.
+	for i := 0; i < 1000; i++ {
+		fw := &failWriter{i}
+		zw.Reset(fw)
+
+		_, werr := zw.Write(d)
+		cerr := zw.Close()
+		if werr != errIO && werr != nil {
+			t.Errorf("test %d, mismatching Write error: got %v, want %v", i, werr, errIO)
+		}
+		if cerr != errIO && fw.n < 0 {
+			t.Errorf("test %d, mismatching Close error: got %v, want %v", i, cerr, errIO)
+		}
+		if fw.n >= 0 {
+			// At this point, the failure threshold was sufficiently high enough
+			// that we wrote the whole stream without any errors.
+			return
+		}
+	}
+}
+
+func TestBestSpeedMatch(t *testing.T) {
+	t.Parallel()
+	cases := []struct {
+		previous, current []byte
+		t, s, want        int32
+	}{{
+		previous: []byte{0, 0, 0, 1, 2},
+		current:  []byte{3, 4, 5, 0, 1, 2, 3, 4, 5},
+		t:        -3,
+		s:        3,
+		want:     6,
+	}, {
+		previous: []byte{0, 0, 0, 1, 2},
+		current:  []byte{2, 4, 5, 0, 1, 2, 3, 4, 5},
+		t:        -3,
+		s:        3,
+		want:     3,
+	}, {
+		previous: []byte{0, 0, 0, 1, 1},
+		current:  []byte{3, 4, 5, 0, 1, 2, 3, 4, 5},
+		t:        -3,
+		s:        3,
+		want:     2,
+	}, {
+		previous: []byte{0, 0, 0, 1, 2},
+		current:  []byte{2, 2, 2, 2, 1, 2, 3, 4, 5},
+		t:        -1,
+		s:        0,
+		want:     4,
+	}, {
+		previous: []byte{0, 0, 0, 1, 2, 3, 4, 5, 2, 2},
+		current:  []byte{2, 2, 2, 2, 1, 2, 3, 4, 5},
+		t:        -7,
+		s:        4,
+		want:     5,
+	}, {
+		previous: []byte{9, 9, 9, 9, 9},
+		current:  []byte{2, 2, 2, 2, 1, 2, 3, 4, 5},
+		t:        -1,
+		s:        0,
+		want:     0,
+	}, {
+		previous: []byte{9, 9, 9, 9, 9},
+		current:  []byte{9, 2, 2, 2, 1, 2, 3, 4, 5},
+		t:        0,
+		s:        1,
+		want:     0,
+	}, {
+		previous: []byte{},
+		current:  []byte{9, 2, 2, 2, 1, 2, 3, 4, 5},
+		t:        -5,
+		s:        1,
+		want:     0,
+	}, {
+		previous: []byte{},
+		current:  []byte{9, 2, 2, 2, 1, 2, 3, 4, 5},
+		t:        -1,
+		s:        1,
+		want:     0,
+	}, {
+		previous: []byte{},
+		current:  []byte{2, 2, 2, 2, 1, 2, 3, 4, 5},
+		t:        0,
+		s:        1,
+		want:     3,
+	}, {
+		previous: []byte{3, 4, 5},
+		current:  []byte{3, 4, 5},
+		t:        -3,
+		s:        0,
+		want:     3,
+	}, {
+		previous: make([]byte, 1000),
+		current:  make([]byte, 1000),
+		t:        -1000,
+		s:        0,
+		want:     maxMatchLength - 4,
+	}, {
+		previous: make([]byte, 200),
+		current:  make([]byte, 500),
+		t:        -200,
+		s:        0,
+		want:     maxMatchLength - 4,
+	}, {
+		previous: make([]byte, 200),
+		current:  make([]byte, 500),
+		t:        0,
+		s:        1,
+		want:     maxMatchLength - 4,
+	}, {
+		previous: make([]byte, maxMatchLength-4),
+		current:  make([]byte, 500),
+		t:        -(maxMatchLength - 4),
+		s:        0,
+		want:     maxMatchLength - 4,
+	}, {
+		previous: make([]byte, 200),
+		current:  make([]byte, 500),
+		t:        -200,
+		s:        400,
+		want:     100,
+	}, {
+		previous: make([]byte, 10),
+		current:  make([]byte, 500),
+		t:        200,
+		s:        400,
+		want:     100,
+	}}
+	for i, c := range cases {
+		e := deflateFast{prev: c.previous}
+		got := e.matchLen(c.s, c.t, c.current)
+		if got != c.want {
+			t.Errorf("Test %d: match length, want %d, got %d", i, c.want, got)
+		}
+	}
+}
+
+func TestBestSpeedMaxMatchOffset(t *testing.T) {
+	t.Parallel()
+	const abc, xyz = "abcdefgh", "stuvwxyz"
+	for _, matchBefore := range []bool{false, true} {
+		for _, extra := range []int{0, inputMargin - 1, inputMargin, inputMargin + 1, 2 * inputMargin} {
+			for offsetAdj := -5; offsetAdj <= +5; offsetAdj++ {
+				report := func(desc string, err error) {
+					t.Errorf("matchBefore=%t, extra=%d, offsetAdj=%d: %s%v",
+						matchBefore, extra, offsetAdj, desc, err)
+				}
+
+				offset := maxMatchOffset + offsetAdj
+
+				// Make src to be a []byte of the form
+				//	"%s%s%s%s%s" % (abc, zeros0, xyzMaybe, abc, zeros1)
+				// where:
+				//	zeros0 is approximately maxMatchOffset zeros.
+				//	xyzMaybe is either xyz or the empty string.
+				//	zeros1 is between 0 and 30 zeros.
+				// The difference between the two abc's will be offset, which
+				// is maxMatchOffset plus or minus a small adjustment.
+				src := make([]byte, offset+len(abc)+extra)
+				copy(src, abc)
+				if !matchBefore {
+					copy(src[offset-len(xyz):], xyz)
+				}
+				copy(src[offset:], abc)
+
+				buf := new(bytes.Buffer)
+				w, err := NewWriter(buf, BestSpeed)
+				if err != nil {
+					report("NewWriter: ", err)
+					continue
+				}
+				if _, err := w.Write(src); err != nil {
+					report("Write: ", err)
+					continue
+				}
+				if err := w.Close(); err != nil {
+					report("Writer.Close: ", err)
+					continue
+				}
+
+				r := NewReader(buf)
+				dst, err := io.ReadAll(r)
+				r.Close()
+				if err != nil {
+					report("ReadAll: ", err)
+					continue
+				}
+
+				if !bytes.Equal(dst, src) {
+					report("", fmt.Errorf("bytes differ after round-tripping"))
+					continue
+				}
+			}
+		}
+	}
+}
+
+func TestBestSpeedShiftOffsets(t *testing.T) {
+	// Test if shiftoffsets properly preserves matches and resets out-of-range matches
+	// seen in https://github.com/golang/go/issues/4142
+	enc := newDeflateFast()
+
+	// testData may not generate internal matches.
+	testData := make([]byte, 32)
+	rng := rand.New(rand.NewSource(0))
+	for i := range testData {
+		testData[i] = byte(rng.Uint32())
+	}
+
+	// Encode the testdata with clean state.
+	// Second part should pick up matches from the first block.
+	wantFirstTokens := len(enc.encode(nil, testData))
+	wantSecondTokens := len(enc.encode(nil, testData))
+
+	if wantFirstTokens <= wantSecondTokens {
+		t.Fatalf("test needs matches between inputs to be generated")
+	}
+	// Forward the current indicator to before wraparound.
+	enc.cur = bufferReset - int32(len(testData))
+
+	// Part 1 before wrap, should match clean state.
+	got := len(enc.encode(nil, testData))
+	if wantFirstTokens != got {
+		t.Errorf("got %d, want %d tokens", got, wantFirstTokens)
+	}
+
+	// Verify we are about to wrap.
+	if enc.cur != bufferReset {
+		t.Errorf("got %d, want e.cur to be at bufferReset (%d)", enc.cur, bufferReset)
+	}
+
+	// Part 2 should match clean state as well even if wrapped.
+	got = len(enc.encode(nil, testData))
+	if wantSecondTokens != got {
+		t.Errorf("got %d, want %d token", got, wantSecondTokens)
+	}
+
+	// Verify that we wrapped.
+	if enc.cur >= bufferReset {
+		t.Errorf("want e.cur to be < bufferReset (%d), got %d", bufferReset, enc.cur)
+	}
+
+	// Forward the current buffer, leaving the matches at the bottom.
+	enc.cur = bufferReset
+	enc.shiftOffsets()
+
+	// Ensure that no matches were picked up.
+	got = len(enc.encode(nil, testData))
+	if wantFirstTokens != got {
+		t.Errorf("got %d, want %d tokens", got, wantFirstTokens)
+	}
+}
+
+func TestMaxStackSize(t *testing.T) {
+	// This test must not run in parallel with other tests as debug.SetMaxStack
+	// affects all goroutines.
+	n := debug.SetMaxStack(1 << 16)
+	defer debug.SetMaxStack(n)
+
+	var wg sync.WaitGroup
+	defer wg.Wait()
+
+	b := make([]byte, 1<<20)
+	for level := HuffmanOnly; level <= BestCompression; level++ {
+		// Run in separate goroutine to increase probability of stack regrowth.
+		wg.Add(1)
+		go func(level int) {
+			defer wg.Done()
+			zw, err := NewWriter(io.Discard, level)
+			if err != nil {
+				t.Errorf("level %d, NewWriter() = %v, want nil", level, err)
+			}
+			if n, err := zw.Write(b); n != len(b) || err != nil {
+				t.Errorf("level %d, Write() = (%d, %v), want (%d, nil)", level, n, err, len(b))
+			}
+			if err := zw.Close(); err != nil {
+				t.Errorf("level %d, Close() = %v, want nil", level, err)
+			}
+			zw.Reset(io.Discard)
+		}(level)
+	}
+}

image/internal/compress/flate/deflatefast.go

@@ -0,0 +1,309 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import "math"
+
+// This encoding algorithm, which prioritizes speed over output size, is
+// based on Snappy's LZ77-style encoder: github.com/golang/snappy
+
+const (
+	tableBits  = 14             // Bits used in the table.
+	tableSize  = 1 << tableBits // Size of the table.
+	tableMask  = tableSize - 1  // Mask for table indices. Redundant, but can eliminate bounds checks.
+	tableShift = 32 - tableBits // Right-shift to get the tableBits most significant bits of a uint32.
+
+	// Reset the buffer offset when reaching this.
+	// Offsets are stored between blocks as int32 values.
+	// Since the offset we are checking against is at the beginning
+	// of the buffer, we need to subtract the current and input
+	// buffer to not risk overflowing the int32.
+	bufferReset = math.MaxInt32 - maxStoreBlockSize*2
+)
+
+func load32(b []byte, i int32) uint32 {
+	b = b[i : i+4 : len(b)] // Help the compiler eliminate bounds checks on the next line.
+	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+func load64(b []byte, i int32) uint64 {
+	b = b[i : i+8 : len(b)] // Help the compiler eliminate bounds checks on the next line.
+	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+}
+
+func hash(u uint32) uint32 {
+	return (u * 0x1e35a7bd) >> tableShift
+}
+
+// These constants are defined by the Snappy implementation so that its
+// assembly implementation can fast-path some 16-bytes-at-a-time copies. They
+// aren't necessary in the pure Go implementation, as we don't use those same
+// optimizations, but using the same thresholds doesn't really hurt.
+const (
+	inputMargin            = 16 - 1
+	minNonLiteralBlockSize = 1 + 1 + inputMargin
+)
+
+type tableEntry struct {
+	val    uint32 // Value at destination
+	offset int32
+}
+
+// deflateFast maintains the table for matches,
+// and the previous byte block for cross block matching.
+type deflateFast struct {
+	table [tableSize]tableEntry
+	prev  []byte // Previous block, zero length if unknown.
+	cur   int32  // Current match offset.
+}
+
+func newDeflateFast() *deflateFast {
+	return &deflateFast{cur: maxStoreBlockSize, prev: make([]byte, 0, maxStoreBlockSize)}
+}
+
+// encode encodes a block given in src and appends tokens
+// to dst and returns the result.
+func (e *deflateFast) encode(dst []token, src []byte) []token {
+	// Ensure that e.cur doesn't wrap.
+	if e.cur >= bufferReset {
+		e.shiftOffsets()
+	}
+
+	// This check isn't in the Snappy implementation, but there, the caller
+	// instead of the callee handles this case.
+	if len(src) < minNonLiteralBlockSize {
+		e.cur += maxStoreBlockSize
+		e.prev = e.prev[:0]
+		return emitLiteral(dst, src)
+	}
+
+	// sLimit is when to stop looking for offset/length copies. The inputMargin
+	// lets us use a fast path for emitLiteral in the main loop, while we are
+	// looking for copies.
+	sLimit := int32(len(src) - inputMargin)
+
+	// nextEmit is where in src the next emitLiteral should start from.
+	nextEmit := int32(0)
+	s := int32(0)
+	cv := load32(src, s)
+	nextHash := hash(cv)
+
+	for {
+		// Copied from the C++ snappy implementation:
+		//
+		// Heuristic match skipping: If 32 bytes are scanned with no matches
+		// found, start looking only at every other byte. If 32 more bytes are
+		// scanned (or skipped), look at every third byte, etc.. When a match
+		// is found, immediately go back to looking at every byte. This is a
+		// small loss (~5% performance, ~0.1% density) for compressible data
+		// due to more bookkeeping, but for non-compressible data (such as
+		// JPEG) it's a huge win since the compressor quickly "realizes" the
+		// data is incompressible and doesn't bother looking for matches
+		// everywhere.
+		//
+		// The "skip" variable keeps track of how many bytes there are since
+		// the last match; dividing it by 32 (ie. right-shifting by five) gives
+		// the number of bytes to move ahead for each iteration.
+		skip := int32(32)
+
+		nextS := s
+		var candidate tableEntry
+		for {
+			s = nextS
+			bytesBetweenHashLookups := skip >> 5
+			nextS = s + bytesBetweenHashLookups
+			skip += bytesBetweenHashLookups
+			if nextS > sLimit {
+				goto emitRemainder
+			}
+			candidate = e.table[nextHash&tableMask]
+			now := load32(src, nextS)
+			e.table[nextHash&tableMask] = tableEntry{offset: s + e.cur, val: cv}
+			nextHash = hash(now)
+
+			offset := s - (candidate.offset - e.cur)
+			if offset > maxMatchOffset || cv != candidate.val {
+				// Out of range or not matched.
+				cv = now
+				continue
+			}
+			break
+		}
+
+		// A 4-byte match has been found. We'll later see if more than 4 bytes
+		// match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+		// them as literal bytes.
+		dst = emitLiteral(dst, src[nextEmit:s])
+
+		// Call emitCopy, and then see if another emitCopy could be our next
+		// move. Repeat until we find no match for the input immediately after
+		// what was consumed by the last emitCopy call.
+		//
+		// If we exit this loop normally then we need to call emitLiteral next,
+		// though we don't yet know how big the literal will be. We handle that
+		// by proceeding to the next iteration of the main loop. We also can
+		// exit this loop via goto if we get close to exhausting the input.
+		for {
+			// Invariant: we have a 4-byte match at s, and no need to emit any
+			// literal bytes prior to s.
+
+			// Extend the 4-byte match as long as possible.
+			//
+			s += 4
+			t := candidate.offset - e.cur + 4
+			l := e.matchLen(s, t, src)
+
+			// matchToken is flate's equivalent of Snappy's emitCopy. (length,offset)
+			dst = append(dst, matchToken(uint32(l+4-baseMatchLength), uint32(s-t-baseMatchOffset)))
+			s += l
+			nextEmit = s
+			if s >= sLimit {
+				goto emitRemainder
+			}
+
+			// We could immediately start working at s now, but to improve
+			// compression we first update the hash table at s-1 and at s. If
+			// another emitCopy is not our next move, also calculate nextHash
+			// at s+1. At least on GOARCH=amd64, these three hash calculations
+			// are faster as one load64 call (with some shifts) instead of
+			// three load32 calls.
+			x := load64(src, s-1)
+			prevHash := hash(uint32(x))
+			e.table[prevHash&tableMask] = tableEntry{offset: e.cur + s - 1, val: uint32(x)}
+			x >>= 8
+			currHash := hash(uint32(x))
+			candidate = e.table[currHash&tableMask]
+			e.table[currHash&tableMask] = tableEntry{offset: e.cur + s, val: uint32(x)}
+
+			offset := s - (candidate.offset - e.cur)
+			if offset > maxMatchOffset || uint32(x) != candidate.val {
+				cv = uint32(x >> 8)
+				nextHash = hash(cv)
+				s++
+				break
+			}
+		}
+	}
+
+emitRemainder:
+	if int(nextEmit) < len(src) {
+		dst = emitLiteral(dst, src[nextEmit:])
+	}
+	e.cur += int32(len(src))
+	e.prev = e.prev[:len(src)]
+	copy(e.prev, src)
+	return dst
+}
+
+func emitLiteral(dst []token, lit []byte) []token {
+	for _, v := range lit {
+		dst = append(dst, literalToken(uint32(v)))
+	}
+	return dst
+}
+
+// matchLen returns the match length between src[s:] and src[t:].
+// t can be negative to indicate the match is starting in e.prev.
+// We assume that src[s-4:s] and src[t-4:t] already match.
+func (e *deflateFast) matchLen(s, t int32, src []byte) int32 {
+	s1 := int(s) + maxMatchLength - 4
+	if s1 > len(src) {
+		s1 = len(src)
+	}
+
+	// If we are inside the current block
+	if t >= 0 {
+		b := src[t:]
+		a := src[s:s1]
+		b = b[:len(a)]
+		// Extend the match to be as long as possible.
+		for i := range a {
+			if a[i] != b[i] {
+				return int32(i)
+			}
+		}
+		return int32(len(a))
+	}
+
+	// We found a match in the previous block.
+	tp := int32(len(e.prev)) + t
+	if tp < 0 {
+		return 0
+	}
+
+	// Extend the match to be as long as possible.
+	a := src[s:s1]
+	b := e.prev[tp:]
+	if len(b) > len(a) {
+		b = b[:len(a)]
+	}
+	a = a[:len(b)]
+	for i := range b {
+		if a[i] != b[i] {
+			return int32(i)
+		}
+	}
+
+	// If we reached our limit, we matched everything we are
+	// allowed to in the previous block and we return.
+	n := int32(len(b))
+	if int(s+n) == s1 {
+		return n
+	}
+
+	// Continue looking for more matches in the current block.
+	a = src[s+n : s1]
+	b = src[:len(a)]
+	for i := range a {
+		if a[i] != b[i] {
+			return int32(i) + n
+		}
+	}
+	return int32(len(a)) + n
+}
+
+// Reset resets the encoding history.
+// This ensures that no matches are made to the previous block.
+func (e *deflateFast) reset() {
+	e.prev = e.prev[:0]
+	// Bump the offset, so all matches will fail distance check.
+	// Nothing should be >= e.cur in the table.
+	e.cur += maxMatchOffset
+
+	// Protect against e.cur wraparound.
+	if e.cur >= bufferReset {
+		e.shiftOffsets()
+	}
+}
+
+// shiftOffsets will shift down all match offset.
+// This is only called in rare situations to prevent integer overflow.
+//
+// See https://golang.org/issue/18636 and https://github.com/golang/go/issues/34121.
+func (e *deflateFast) shiftOffsets() {
+	if len(e.prev) == 0 {
+		// We have no history; just clear the table.
+		for i := range e.table[:] {
+			e.table[i] = tableEntry{}
+		}
+		e.cur = maxMatchOffset + 1
+		return
+	}
+
+	// Shift down everything in the table that isn't already too far away.
+	for i := range e.table[:] {
+		v := e.table[i].offset - e.cur + maxMatchOffset + 1
+		if v < 0 {
+			// We want to reset e.cur to maxMatchOffset + 1, so we need to shift
+			// all table entries down by (e.cur - (maxMatchOffset + 1)).
+			// Because we ignore matches > maxMatchOffset, we can cap
+			// any negative offsets at 0.
+			v = 0
+		}
+		e.table[i].offset = v
+	}
+	e.cur = maxMatchOffset + 1
+}

image/internal/compress/flate/dict_decoder.go

@@ -0,0 +1,186 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+// dictDecoder implements the LZ77 sliding dictionary as used in decompression.
+// LZ77 decompresses data through sequences of two forms of commands:
+//
+//	* Literal insertions: Runs of one or more symbols are inserted into the data
+//	stream as is. This is accomplished through the writeByte method for a
+//	single symbol, or combinations of writeSlice/writeMark for multiple symbols.
+//	Any valid stream must start with a literal insertion if no preset dictionary
+//	is used.
+//
+//	* Backward copies: Runs of one or more symbols are copied from previously
+//	emitted data. Backward copies come as the tuple (dist, length) where dist
+//	determines how far back in the stream to copy from and length determines how
+//	many bytes to copy. Note that it is valid for the length to be greater than
+//	the distance. Since LZ77 uses forward copies, that situation is used to
+//	perform a form of run-length encoding on repeated runs of symbols.
+//	The writeCopy and tryWriteCopy are used to implement this command.
+//
+// For performance reasons, this implementation performs little to no sanity
+// checks about the arguments. As such, the invariants documented for each
+// method call must be respected.
+type dictDecoder struct {
+	hist []byte // Sliding window history
+
+	// Invariant: 0 <= rdPos <= wrPos <= len(hist)
+	wrPos int  // Current output position in buffer
+	rdPos int  // Have emitted hist[:rdPos] already
+	full  bool // Has a full window length been written yet?
+}
+
+// To minimize the memory usage in TinyGo, it is defined as a fixed array
+// instead of a make().
+var ddHistBuf [1 << 15]byte
+
+// init initializes dictDecoder to have a sliding window dictionary of the given
+// size. If a preset dict is provided, it will initialize the dictionary with
+// the contents of dict.
+func (dd *dictDecoder) init(size int, dict []byte) {
+	*dd = dictDecoder{hist: dd.hist}
+
+	if cap(dd.hist) < size {
+		dd.hist = ddHistBuf[:size]
+	}
+	dd.hist = dd.hist[:size]
+
+	if len(dict) > len(dd.hist) {
+		dict = dict[len(dict)-len(dd.hist):]
+	}
+	dd.wrPos = copy(dd.hist, dict)
+	if dd.wrPos == len(dd.hist) {
+		dd.wrPos = 0
+		dd.full = true
+	}
+	dd.rdPos = dd.wrPos
+}
+
+// histSize reports the total amount of historical data in the dictionary.
+func (dd *dictDecoder) histSize() int {
+	if dd.full {
+		return len(dd.hist)
+	}
+	return dd.wrPos
+}
+
+// availRead reports the number of bytes that can be flushed by readFlush.
+func (dd *dictDecoder) availRead() int {
+	return dd.wrPos - dd.rdPos
+}
+
+// availWrite reports the available amount of output buffer space.
+func (dd *dictDecoder) availWrite() int {
+	return len(dd.hist) - dd.wrPos
+}
+
+// writeSlice returns a slice of the available buffer to write data to.
+//
+// This invariant will be kept: len(s) <= availWrite()
+func (dd *dictDecoder) writeSlice() []byte {
+	return dd.hist[dd.wrPos:]
+}
+
+// writeMark advances the writer pointer by cnt.
+//
+// This invariant must be kept: 0 <= cnt <= availWrite()
+func (dd *dictDecoder) writeMark(cnt int) {
+	dd.wrPos += cnt
+}
+
+// writeByte writes a single byte to the dictionary.
+//
+// This invariant must be kept: 0 < availWrite()
+func (dd *dictDecoder) writeByte(c byte) {
+	dd.hist[dd.wrPos] = c
+	dd.wrPos++
+}
+
+// writeCopy copies a string at a given (dist, length) to the output.
+// This returns the number of bytes copied and may be less than the requested
+// length if the available space in the output buffer is too small.
+//
+// This invariant must be kept: 0 < dist <= histSize()
+func (dd *dictDecoder) writeCopy(dist, length int) int {
+	dstBase := dd.wrPos
+	dstPos := dstBase
+	srcPos := dstPos - dist
+	endPos := dstPos + length
+	if endPos > len(dd.hist) {
+		endPos = len(dd.hist)
+	}
+
+	// Copy non-overlapping section after destination position.
+	//
+	// This section is non-overlapping in that the copy length for this section
+	// is always less than or equal to the backwards distance. This can occur
+	// if a distance refers to data that wraps-around in the buffer.
+	// Thus, a backwards copy is performed here; that is, the exact bytes in
+	// the source prior to the copy is placed in the destination.
+	if srcPos < 0 {
+		srcPos += len(dd.hist)
+		dstPos += copy(dd.hist[dstPos:endPos], dd.hist[srcPos:])
+		srcPos = 0
+	}
+
+	// Copy possibly overlapping section before destination position.
+	//
+	// This section can overlap if the copy length for this section is larger
+	// than the backwards distance. This is allowed by LZ77 so that repeated
+	// strings can be succinctly represented using (dist, length) pairs.
+	// Thus, a forwards copy is performed here; that is, the bytes copied is
+	// possibly dependent on the resulting bytes in the destination as the copy
+	// progresses along. This is functionally equivalent to the following:
+	//
+	//	for i := 0; i < endPos-dstPos; i++ {
+	//		dd.hist[dstPos+i] = dd.hist[srcPos+i]
+	//	}
+	//	dstPos = endPos
+	//
+	for dstPos < endPos {
+		dstPos += copy(dd.hist[dstPos:endPos], dd.hist[srcPos:dstPos])
+	}
+
+	dd.wrPos = dstPos
+	return dstPos - dstBase
+}
+
+// tryWriteCopy tries to copy a string at a given (distance, length) to the
+// output. This specialized version is optimized for short distances.
+//
+// This method is designed to be inlined for performance reasons.
+//
+// This invariant must be kept: 0 < dist <= histSize()
+func (dd *dictDecoder) tryWriteCopy(dist, length int) int {
+	dstPos := dd.wrPos
+	endPos := dstPos + length
+	if dstPos < dist || endPos > len(dd.hist) {
+		return 0
+	}
+	dstBase := dstPos
+	srcPos := dstPos - dist
+
+	// Copy possibly overlapping section before destination position.
+	for dstPos < endPos {
+		dstPos += copy(dd.hist[dstPos:endPos], dd.hist[srcPos:dstPos])
+	}
+
+	dd.wrPos = dstPos
+	return dstPos - dstBase
+}
+
+// readFlush returns a slice of the historical buffer that is ready to be
+// emitted to the user. The data returned by readFlush must be fully consumed
+// before calling any other dictDecoder methods.
+func (dd *dictDecoder) readFlush() []byte {
+	toRead := dd.hist[dd.rdPos:dd.wrPos]
+	dd.rdPos = dd.wrPos
+	if dd.wrPos == len(dd.hist) {
+		dd.wrPos, dd.rdPos = 0, 0
+		dd.full = true
+	}
+	return toRead
+}

image/internal/compress/flate/dict_decoder_test.go

@@ -0,0 +1,139 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func TestDictDecoder(t *testing.T) {
+	const (
+		abc  = "ABC\n"
+		fox  = "The quick brown fox jumped over the lazy dog!\n"
+		poem = "The Road Not Taken\nRobert Frost\n" +
+			"\n" +
+			"Two roads diverged in a yellow wood,\n" +
+			"And sorry I could not travel both\n" +
+			"And be one traveler, long I stood\n" +
+			"And looked down one as far as I could\n" +
+			"To where it bent in the undergrowth;\n" +
+			"\n" +
+			"Then took the other, as just as fair,\n" +
+			"And having perhaps the better claim,\n" +
+			"Because it was grassy and wanted wear;\n" +
+			"Though as for that the passing there\n" +
+			"Had worn them really about the same,\n" +
+			"\n" +
+			"And both that morning equally lay\n" +
+			"In leaves no step had trodden black.\n" +
+			"Oh, I kept the first for another day!\n" +
+			"Yet knowing how way leads on to way,\n" +
+			"I doubted if I should ever come back.\n" +
+			"\n" +
+			"I shall be telling this with a sigh\n" +
+			"Somewhere ages and ages hence:\n" +
+			"Two roads diverged in a wood, and I-\n" +
+			"I took the one less traveled by,\n" +
+			"And that has made all the difference.\n"
+	)
+
+	var poemRefs = []struct {
+		dist   int // Backward distance (0 if this is an insertion)
+		length int // Length of copy or insertion
+	}{
+		{0, 38}, {33, 3}, {0, 48}, {79, 3}, {0, 11}, {34, 5}, {0, 6}, {23, 7},
+		{0, 8}, {50, 3}, {0, 2}, {69, 3}, {34, 5}, {0, 4}, {97, 3}, {0, 4},
+		{43, 5}, {0, 6}, {7, 4}, {88, 7}, {0, 12}, {80, 3}, {0, 2}, {141, 4},
+		{0, 1}, {196, 3}, {0, 3}, {157, 3}, {0, 6}, {181, 3}, {0, 2}, {23, 3},
+		{77, 3}, {28, 5}, {128, 3}, {110, 4}, {70, 3}, {0, 4}, {85, 6}, {0, 2},
+		{182, 6}, {0, 4}, {133, 3}, {0, 7}, {47, 5}, {0, 20}, {112, 5}, {0, 1},
+		{58, 3}, {0, 8}, {59, 3}, {0, 4}, {173, 3}, {0, 5}, {114, 3}, {0, 4},
+		{92, 5}, {0, 2}, {71, 3}, {0, 2}, {76, 5}, {0, 1}, {46, 3}, {96, 4},
+		{130, 4}, {0, 3}, {360, 3}, {0, 3}, {178, 5}, {0, 7}, {75, 3}, {0, 3},
+		{45, 6}, {0, 6}, {299, 6}, {180, 3}, {70, 6}, {0, 1}, {48, 3}, {66, 4},
+		{0, 3}, {47, 5}, {0, 9}, {325, 3}, {0, 1}, {359, 3}, {318, 3}, {0, 2},
+		{199, 3}, {0, 1}, {344, 3}, {0, 3}, {248, 3}, {0, 10}, {310, 3}, {0, 3},
+		{93, 6}, {0, 3}, {252, 3}, {157, 4}, {0, 2}, {273, 5}, {0, 14}, {99, 4},
+		{0, 1}, {464, 4}, {0, 2}, {92, 4}, {495, 3}, {0, 1}, {322, 4}, {16, 4},
+		{0, 3}, {402, 3}, {0, 2}, {237, 4}, {0, 2}, {432, 4}, {0, 1}, {483, 5},
+		{0, 2}, {294, 4}, {0, 2}, {306, 3}, {113, 5}, {0, 1}, {26, 4}, {164, 3},
+		{488, 4}, {0, 1}, {542, 3}, {248, 6}, {0, 5}, {205, 3}, {0, 8}, {48, 3},
+		{449, 6}, {0, 2}, {192, 3}, {328, 4}, {9, 5}, {433, 3}, {0, 3}, {622, 25},
+		{615, 5}, {46, 5}, {0, 2}, {104, 3}, {475, 10}, {549, 3}, {0, 4}, {597, 8},
+		{314, 3}, {0, 1}, {473, 6}, {317, 5}, {0, 1}, {400, 3}, {0, 3}, {109, 3},
+		{151, 3}, {48, 4}, {0, 4}, {125, 3}, {108, 3}, {0, 2},
+	}
+
+	var got, want bytes.Buffer
+	var dd dictDecoder
+	dd.init(1<<11, nil)
+
+	var writeCopy = func(dist, length int) {
+		for length > 0 {
+			cnt := dd.tryWriteCopy(dist, length)
+			if cnt == 0 {
+				cnt = dd.writeCopy(dist, length)
+			}
+
+			length -= cnt
+			if dd.availWrite() == 0 {
+				got.Write(dd.readFlush())
+			}
+		}
+	}
+	var writeString = func(str string) {
+		for len(str) > 0 {
+			cnt := copy(dd.writeSlice(), str)
+			str = str[cnt:]
+			dd.writeMark(cnt)
+			if dd.availWrite() == 0 {
+				got.Write(dd.readFlush())
+			}
+		}
+	}
+
+	writeString(".")
+	want.WriteByte('.')
+
+	str := poem
+	for _, ref := range poemRefs {
+		if ref.dist == 0 {
+			writeString(str[:ref.length])
+		} else {
+			writeCopy(ref.dist, ref.length)
+		}
+		str = str[ref.length:]
+	}
+	want.WriteString(poem)
+
+	writeCopy(dd.histSize(), 33)
+	want.Write(want.Bytes()[:33])
+
+	writeString(abc)
+	writeCopy(len(abc), 59*len(abc))
+	want.WriteString(strings.Repeat(abc, 60))
+
+	writeString(fox)
+	writeCopy(len(fox), 9*len(fox))
+	want.WriteString(strings.Repeat(fox, 10))
+
+	writeString(".")
+	writeCopy(1, 9)
+	want.WriteString(strings.Repeat(".", 10))
+
+	writeString(strings.ToUpper(poem))
+	writeCopy(len(poem), 7*len(poem))
+	want.WriteString(strings.Repeat(strings.ToUpper(poem), 8))
+
+	writeCopy(dd.histSize(), 10)
+	want.Write(want.Bytes()[want.Len()-dd.histSize():][:10])
+
+	got.Write(dd.readFlush())
+	if got.String() != want.String() {
+		t.Errorf("final string mismatch:\ngot  %q\nwant %q", got.String(), want.String())
+	}
+}

image/internal/compress/flate/example_test.go

@@ -0,0 +1,243 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate_test
+
+import (
+	"bytes"
+	"compress/flate"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"strings"
+	"sync"
+)
+
+// In performance critical applications, Reset can be used to discard the
+// current compressor or decompressor state and reinitialize them quickly
+// by taking advantage of previously allocated memory.
+func Example_reset() {
+	proverbs := []string{
+		"Don't communicate by sharing memory, share memory by communicating.\n",
+		"Concurrency is not parallelism.\n",
+		"The bigger the interface, the weaker the abstraction.\n",
+		"Documentation is for users.\n",
+	}
+
+	var r strings.Reader
+	var b bytes.Buffer
+	buf := make([]byte, 32<<10)
+
+	zw, err := flate.NewWriter(nil, flate.DefaultCompression)
+	if err != nil {
+		log.Fatal(err)
+	}
+	zr := flate.NewReader(nil)
+
+	for _, s := range proverbs {
+		r.Reset(s)
+		b.Reset()
+
+		// Reset the compressor and encode from some input stream.
+		zw.Reset(&b)
+		if _, err := io.CopyBuffer(zw, &r, buf); err != nil {
+			log.Fatal(err)
+		}
+		if err := zw.Close(); err != nil {
+			log.Fatal(err)
+		}
+
+		// Reset the decompressor and decode to some output stream.
+		if err := zr.(flate.Resetter).Reset(&b, nil); err != nil {
+			log.Fatal(err)
+		}
+		if _, err := io.CopyBuffer(os.Stdout, zr, buf); err != nil {
+			log.Fatal(err)
+		}
+		if err := zr.Close(); err != nil {
+			log.Fatal(err)
+		}
+	}
+
+	// Output:
+	// Don't communicate by sharing memory, share memory by communicating.
+	// Concurrency is not parallelism.
+	// The bigger the interface, the weaker the abstraction.
+	// Documentation is for users.
+}
+
+// A preset dictionary can be used to improve the compression ratio.
+// The downside to using a dictionary is that the compressor and decompressor
+// must agree in advance what dictionary to use.
+func Example_dictionary() {
+	// The dictionary is a string of bytes. When compressing some input data,
+	// the compressor will attempt to substitute substrings with matches found
+	// in the dictionary. As such, the dictionary should only contain substrings
+	// that are expected to be found in the actual data stream.
+	const dict = `<?xml version="1.0"?>` + `<book>` + `<data>` + `<meta name="` + `" content="`
+
+	// The data to compress should (but is not required to) contain frequent
+	// substrings that match those in the dictionary.
+	const data = `<?xml version="1.0"?>
+<book>
+	<meta name="title" content="The Go Programming Language"/>
+	<meta name="authors" content="Alan Donovan and Brian Kernighan"/>
+	<meta name="published" content="2015-10-26"/>
+	<meta name="isbn" content="978-0134190440"/>
+	<data>...</data>
+</book>
+`
+
+	var b bytes.Buffer
+
+	// Compress the data using the specially crafted dictionary.
+	zw, err := flate.NewWriterDict(&b, flate.DefaultCompression, []byte(dict))
+	if err != nil {
+		log.Fatal(err)
+	}
+	if _, err := io.Copy(zw, strings.NewReader(data)); err != nil {
+		log.Fatal(err)
+	}
+	if err := zw.Close(); err != nil {
+		log.Fatal(err)
+	}
+
+	// The decompressor must use the same dictionary as the compressor.
+	// Otherwise, the input may appear as corrupted.
+	fmt.Println("Decompressed output using the dictionary:")
+	zr := flate.NewReaderDict(bytes.NewReader(b.Bytes()), []byte(dict))
+	if _, err := io.Copy(os.Stdout, zr); err != nil {
+		log.Fatal(err)
+	}
+	if err := zr.Close(); err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Println()
+
+	// Substitute all of the bytes in the dictionary with a '#' to visually
+	// demonstrate the approximate effectiveness of using a preset dictionary.
+	fmt.Println("Substrings matched by the dictionary are marked with #:")
+	hashDict := []byte(dict)
+	for i := range hashDict {
+		hashDict[i] = '#'
+	}
+	zr = flate.NewReaderDict(&b, hashDict)
+	if _, err := io.Copy(os.Stdout, zr); err != nil {
+		log.Fatal(err)
+	}
+	if err := zr.Close(); err != nil {
+		log.Fatal(err)
+	}
+
+	// Output:
+	// Decompressed output using the dictionary:
+	// <?xml version="1.0"?>
+	// <book>
+	// 	<meta name="title" content="The Go Programming Language"/>
+	// 	<meta name="authors" content="Alan Donovan and Brian Kernighan"/>
+	// 	<meta name="published" content="2015-10-26"/>
+	// 	<meta name="isbn" content="978-0134190440"/>
+	// 	<data>...</data>
+	// </book>
+	//
+	// Substrings matched by the dictionary are marked with #:
+	// #####################
+	// ######
+	// 	############title###########The Go Programming Language"/#
+	// 	############authors###########Alan Donovan and Brian Kernighan"/#
+	// 	############published###########2015-10-26"/#
+	// 	############isbn###########978-0134190440"/#
+	// 	######...</#####
+	// </#####
+}
+
+// DEFLATE is suitable for transmitting compressed data across the network.
+func Example_synchronization() {
+	var wg sync.WaitGroup
+	defer wg.Wait()
+
+	// Use io.Pipe to simulate a network connection.
+	// A real network application should take care to properly close the
+	// underlying connection.
+	rp, wp := io.Pipe()
+
+	// Start a goroutine to act as the transmitter.
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+
+		zw, err := flate.NewWriter(wp, flate.BestSpeed)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		b := make([]byte, 256)
+		for _, m := range strings.Fields("A long time ago in a galaxy far, far away...") {
+			// We use a simple framing format where the first byte is the
+			// message length, followed the message itself.
+			b[0] = uint8(copy(b[1:], m))
+
+			if _, err := zw.Write(b[:1+len(m)]); err != nil {
+				log.Fatal(err)
+			}
+
+			// Flush ensures that the receiver can read all data sent so far.
+			if err := zw.Flush(); err != nil {
+				log.Fatal(err)
+			}
+		}
+
+		if err := zw.Close(); err != nil {
+			log.Fatal(err)
+		}
+	}()
+
+	// Start a goroutine to act as the receiver.
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+
+		zr := flate.NewReader(rp)
+
+		b := make([]byte, 256)
+		for {
+			// Read the message length.
+			// This is guaranteed to return for every corresponding
+			// Flush and Close on the transmitter side.
+			if _, err := io.ReadFull(zr, b[:1]); err != nil {
+				if err == io.EOF {
+					break // The transmitter closed the stream
+				}
+				log.Fatal(err)
+			}
+
+			// Read the message content.
+			n := int(b[0])
+			if _, err := io.ReadFull(zr, b[:n]); err != nil {
+				log.Fatal(err)
+			}
+
+			fmt.Printf("Received %d bytes: %s\n", n, b[:n])
+		}
+		fmt.Println()
+
+		if err := zr.Close(); err != nil {
+			log.Fatal(err)
+		}
+	}()
+
+	// Output:
+	// Received 1 bytes: A
+	// Received 4 bytes: long
+	// Received 4 bytes: time
+	// Received 3 bytes: ago
+	// Received 2 bytes: in
+	// Received 1 bytes: a
+	// Received 6 bytes: galaxy
+	// Received 4 bytes: far,
+	// Received 3 bytes: far
+	// Received 7 bytes: away...
+}