docs: update CHANGELOG for release 0.29

Signed-off-by: deadprogram <ron@hybridgroup.com>

.github/workflows/build-macos.yml

@@ -27,7 +27,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.20'
+          go-version: '1.21'
           cache: true
       - name: Restore LLVM source cache
         uses: actions/cache/restore@v3
@@ -108,7 +108,7 @@ jobs:
         # We're doing the former here, to keep artifact uploads fast.
         uses: actions/upload-artifact@v2
         with:
-          name: release-double-zipped
+          name: darwin-amd64-double-zipped
           path: build/tinygo.darwin-amd64.tar.gz
       - name: Smoke tests
         shell: bash
@@ -126,7 +126,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.20'
+          go-version: '1.21'
           cache: true
       - name: Build TinyGo
         run: go install

.github/workflows/linux.yml

@@ -18,7 +18,7 @@ jobs:
     # statically linked binary.
     runs-on: ubuntu-latest
     container:
-      image: golang:1.20-alpine
+      image: golang:1.21-alpine
     steps:
       - name: Install apk dependencies
         # tar: needed for actions/cache@v3
@@ -135,7 +135,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.20'
+          go-version: '1.21'
           cache: true
       - name: Install wasmtime
         run: |
@@ -153,6 +153,7 @@ jobs:
           tar -C ~/lib -xf tinygo.linux-amd64.tar.gz
           ln -s ~/lib/tinygo/bin/tinygo ~/go/bin/tinygo
       - run: make tinygo-test-wasi-fast
+      - run: make tinygo-test-wasip1-fast
       - run: make smoketest
   assert-test-linux:
     # Run all tests that can run on Linux, with LLVM assertions enabled to catch
@@ -177,12 +178,12 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.20'
+          go-version: '1.21'
           cache: true
       - name: Install Node.js
         uses: actions/setup-node@v3
         with:
-          node-version: '14'
+          node-version: '16'
       - name: Install wasmtime
         run: |
           mkdir -p $HOME/.wasmtime $HOME/.wasmtime/bin
@@ -290,7 +291,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.20'
+          go-version: '1.21'
           cache: true
       - name: Restore LLVM source cache
         uses: actions/cache/restore@v3
@@ -407,7 +408,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.20'
+          go-version: '1.21'
           cache: true
       - name: Restore LLVM source cache
         uses: actions/cache/restore@v3

.github/workflows/windows.yml

@@ -35,7 +35,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.20'
+          go-version: '1.21'
           cache: true
       - name: Restore cached LLVM source
         uses: actions/cache/restore@v3
@@ -118,7 +118,7 @@ jobs:
         # We're doing the former here, to keep artifact uploads fast.
         uses: actions/upload-artifact@v3
         with:
-          name: release-double-zipped
+          name: windows-amd64-double-zipped
           path: build/release/release.zip
 
   smoke-test-windows:
@@ -143,12 +143,12 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.20'
+          go-version: '1.21'
           cache: true
       - name: Download TinyGo build
         uses: actions/download-artifact@v2
         with:
-          name: release-double-zipped
+          name: windows-amd64-double-zipped
           path: build/
       - name: Unzip TinyGo build
         shell: bash
@@ -173,12 +173,12 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.20'
+          go-version: '1.21'
           cache: true
       - name: Download TinyGo build
         uses: actions/download-artifact@v2
         with:
-          name: release-double-zipped
+          name: windows-amd64-double-zipped
           path: build/
       - name: Unzip TinyGo build
         shell: bash
@@ -209,12 +209,12 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.20'
+          go-version: '1.21'
           cache: true
       - name: Download TinyGo build
         uses: actions/download-artifact@v2
         with:
-          name: release-double-zipped
+          name: windows-amd64-double-zipped
           path: build/
       - name: Unzip TinyGo build
         shell: bash

.gitmodules

@@ -31,3 +31,6 @@
 [submodule "lib/macos-minimal-sdk"]
 	path = lib/macos-minimal-sdk
 	url = https://github.com/aykevl/macos-minimal-sdk.git
+[submodule "lib/renesas-svd"]
+	path = lib/renesas-svd
+	url = https://github.com/tinygo-org/renesas-svd.git

CHANGELOG.md

@@ -1,3 +1,74 @@
+0.29.0
+---
+
+* **general**
+  - Go 1.21 support
+  - use https for renesas submodule #3856
+  - ci: rename release-double-zipped to something more useful
+  - ci: update Node.js from version 14 to version 16
+  - ci: switch GH actions builds to use Go 1.21 final release
+  - docker: update clang to version 15
+  - docker: use Go 1.21 for Docker dev container build
+  - `main`: add target JSON file in `tinygo info` output
+  - `main`: improve detection of filesystems
+  - `main`: use `go env` instead of doing all detection manually
+  - make: add make task to generate Renesas device wrappers
+  - make: add task to check NodeJS version before running tests
+  - add submodule for Renesas SVD file mirror repo
+  - update to go-serial package v1.6.0
+  - `testing`: add Testing function
+  - `tools/gen-device-svd`: small changes needed for Renesas MCUs
+* **compiler**
+  - `builder`: update message for max supported Go version
+  - `compiler,reflect`: NumMethods reports exported methods only
+  - `compiler`: add compiler-rt and wasm symbols to table
+  - `compiler`: add compiler-rt to wasm.json
+  - `compiler`: add min and max builtin support
+  - `compiler`: implement clear builtin for maps
+  - `compiler`: implement clear builtin for slices
+  - `compiler`: improve panic message when a runtime call is unavailable
+  - `compiler`: update .ll test output
+  - `loader`: merge go.env file which is now required starting in Go 1.21 to correctly get required packages
+* **standard library**
+  - `os`: define ErrNoDeadline
+  - `reflect`: Add FieldByNameFunc
+  - `reflect`: add SetZero
+  - `reflect`: fix iterating over maps with interface{} keys
+  - `reflect`: implement Value.Grow
+  - `reflect`: remove unecessary heap allocations
+  - `reflect`: use .key() instead of a type assert
+  - `sync`: add implementation from upstream Go for OnceFunc, OnceValue, and OnceValues
+* **targets**
+  - `machine`: UART refactor (#3832)
+  - `machine/avr`: pin change interrupt
+  - `machine/macropad_rp2040`: add machine.BUTTON
+  - `machine/nrf`: add I2C timeout
+  - `machine/nrf`: wait for stop condition after reading from the I2C bus
+  - `machine/nRF52`: set SPI TX/RX lengths even data is empty. Fixes #3868 (#3877)
+  - `machine/rp2040`: add missing suffix to CMD_READ_STATUS
+  - `machine/rp2040`: add NoPin support
+  - `machine/rp2040`: move flash related functions into separate file from C imports for correct  - LSP. Fixes #3852
+  - `machine/rp2040`: wait for 1000 us after flash reset to avoid issues with busy USB bus
+  - `machine/samd51,rp2040,nrf528xx,stm32`: implement watchdog
+  - `machine/samd51`: fix i2cTimeout was decreasing due to cache activation
+  - `machine/usb`: Add support for HID Keyboard LEDs
+  - `machine/usb`: allow USB Endpoint settings to be changed externally
+  - `machine/usb`: refactor endpoint configuration
+  - `machine/usb`: remove usbDescriptorConfig
+  - `machine/usb/hid,joystick`: fix hidreport (3) (#3802)
+  - `machine/usb/hid`: add RxHandler interface
+  - `machine/usb/hid`: rename Handler() to TxHandler()
+  - `wasi`: allow zero inodes when reading directories
+  - `wasm`: add support for GOOS=wasip1
+  - `wasm`: fix functions exported through //export
+  - `wasm`: remove i64 workaround, use BigInt instead
+  - `example`: adjust time offset
+  - `example`: simplify pininterrupt
+* **boards**
+  - `targets`: add AKIZUKI DENSHI AE-RP2040
+  - `targets`: adding new uf2 target for PCA10056 (#3765)
+
+
 0.28.0
 ---
 

Dockerfile

@@ -1,8 +1,8 @@
 # tinygo-llvm stage obtains the llvm source for TinyGo
-FROM golang:1.20 AS tinygo-llvm
+FROM golang:1.21 AS tinygo-llvm
 
 RUN apt-get update && \
-    apt-get install -y apt-utils make cmake clang-11 ninja-build
+    apt-get install -y apt-utils make cmake clang-15 ninja-build
 
 COPY ./Makefile /tinygo/Makefile
 

Makefile

@@ -232,6 +232,10 @@ gen-device-rp: build/gen-device-svd
 	./build/gen-device-svd -source=https://github.com/posborne/cmsis-svd/tree/master/data/RaspberryPi lib/cmsis-svd/data/RaspberryPi/ src/device/rp/
 	GO111MODULE=off $(GO) fmt ./src/device/rp
 
+gen-device-renesas: build/gen-device-svd
+	./build/gen-device-svd -source=https://github.com/tinygo-org/renesas-svd lib/renesas-svd/ src/device/renesas/
+	GO111MODULE=off $(GO) fmt ./src/device/renesas
+
 # Get LLVM sources.
 $(LLVM_PROJECTDIR)/llvm:
 	git clone -b xtensa_release_15.x --depth=1 https://github.com/espressif/llvm-project $(LLVM_PROJECTDIR)
@@ -263,12 +267,22 @@ lib/wasi-libc/sysroot/lib/wasm32-wasi/libc.a:
 	@if [ ! -e lib/wasi-libc/Makefile ]; then echo "Submodules have not been downloaded. Please download them using:\n  git submodule update --init"; exit 1; fi
 	cd lib/wasi-libc && make -j4 EXTRA_CFLAGS="-O2 -g -DNDEBUG -mnontrapping-fptoint -msign-ext" MALLOC_IMPL=none CC=$(CLANG) AR=$(LLVM_AR) NM=$(LLVM_NM)
 
+# Check for Node.js used during WASM tests.
+NODEJS_VERSION := $(word 1,$(subst ., ,$(shell node -v | cut -c 2-)))
+MIN_NODEJS_VERSION=16
+
+.PHONY: check-nodejs-version
+check-nodejs-version:
+ifeq (, $(shell which node))
+	@echo "Install NodeJS version 16+ to run tests."; exit 1;
+endif
+	@if [ $(NODEJS_VERSION) -lt $(MIN_NODEJS_VERSION) ]; then echo "Install NodeJS version 16+ to run tests."; exit 1; fi
 
 # Build the Go compiler.
 tinygo:
 	@if [ ! -f "$(LLVM_BUILDDIR)/bin/llvm-config" ]; then echo "Fetch and build LLVM first by running:"; echo "  make llvm-source"; echo "  make $(LLVM_BUILDDIR)"; exit 1; fi
 	CGO_CPPFLAGS="$(CGO_CPPFLAGS)" CGO_CXXFLAGS="$(CGO_CXXFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" $(GOENVFLAGS) $(GO) build -buildmode exe -o build/tinygo$(EXE) -tags "byollvm osusergo" -ldflags="-X github.com/tinygo-org/tinygo/goenv.GitSha1=`git rev-parse --short HEAD`" .
-test: wasi-libc
+test: wasi-libc check-nodejs-version
 	CGO_CPPFLAGS="$(CGO_CPPFLAGS)" CGO_CXXFLAGS="$(CGO_CXXFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" $(GO) test $(GOTESTFLAGS) -timeout=20m -buildmode exe -tags "byollvm osusergo" ./builder ./cgo ./compileopts ./compiler ./interp ./transform .
 
 # Standard library packages that pass tests on darwin, linux, wasi, and windows, but take over a minute in wasi
@@ -413,8 +427,12 @@ tinygo-bench-fast:
 # Same thing, except for wasi rather than the current platform.
 tinygo-test-wasi:
 	$(TINYGO) test -target wasi $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_SLOW) ./tests/runtime_wasi
+tinygo-test-wasip1:
+	GOOS=wasip1 GOARCH=wasm $(TINYGO) test $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_SLOW) ./tests/runtime_wasi
 tinygo-test-wasi-fast:
 	$(TINYGO) test -target wasi $(TEST_PACKAGES_FAST) ./tests/runtime_wasi
+tinygo-test-wasip1-fast:
+	GOOS=wasip1 GOARCH=wasm $(TINYGO) test $(TEST_PACKAGES_FAST) ./tests/runtime_wasi
 tinygo-bench-wasi:
 	$(TINYGO) test -target wasi -bench . $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_SLOW)
 tinygo-bench-wasi-fast:
@@ -478,12 +496,16 @@ smoketest:
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/test
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=pca10040            examples/time-offset
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=wioterminal         examples/hid-mouse
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=wioterminal         examples/hid-keyboard
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=feather-rp2040      examples/i2c-target
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=feather-rp2040      examples/watchdog
+	@$(MD5SUM) test.hex
 	# test simulated boards on play.tinygo.org
 ifneq ($(WASM), 0)
 	$(TINYGO) build -size short -o test.wasm -tags=arduino              examples/blinky1
@@ -642,6 +664,8 @@ endif
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=gopher-badge      examples/blinky1
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=ae-rp2040           examples/echo
+	@$(MD5SUM) test.hex
 	# test pwm
 	$(TINYGO) build -size short -o test.hex -target=itsybitsy-m0        examples/pwm
 	@$(MD5SUM) test.hex

builder/ar.go

@@ -12,6 +12,7 @@ import (
 	"path/filepath"
 	"time"
 
+	wasm "github.com/aykevl/go-wasm"
 	"github.com/blakesmith/ar"
 )
 
@@ -74,8 +75,25 @@ func makeArchive(arfile *os.File, objs []string) error {
 					fileIndex int
 				}{symbol.Name, i})
 			}
+		} else if dbg, err := wasm.Parse(objfile); err == nil {
+			for _, s := range dbg.Sections {
+				switch section := s.(type) {
+				case *wasm.SectionImport:
+					for _, ln := range section.Entries {
+
+						if ln.Kind != wasm.ExtKindFunction {
+							// Not a function
+							continue
+						}
+						symbolTable = append(symbolTable, struct {
+							name      string
+							fileIndex int
+						}{ln.Field, i})
+					}
+				}
+			}
 		} else {
-			return fmt.Errorf("failed to open file %s as ELF or PE/COFF: %w", objpath, err)
+			return fmt.Errorf("failed to open file %s as WASM, ELF or PE/COFF: %w", objpath, err)
 		}
 
 		// Close file, to avoid issues with too many open files (especially on

builder/build.go

@@ -217,19 +217,27 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe
 	var packageJobs []*compileJob
 	packageActionIDJobs := make(map[string]*compileJob)
 
+	if config.Options.GlobalValues == nil {
+		config.Options.GlobalValues = make(map[string]map[string]string)
+	}
 	if config.Options.GlobalValues["runtime"]["buildVersion"] == "" {
 		version := goenv.Version
 		if strings.HasSuffix(goenv.Version, "-dev") && goenv.GitSha1 != "" {
 			version += "-" + goenv.GitSha1
 		}
-		if config.Options.GlobalValues == nil {
-			config.Options.GlobalValues = make(map[string]map[string]string)
-		}
 		if config.Options.GlobalValues["runtime"] == nil {
 			config.Options.GlobalValues["runtime"] = make(map[string]string)
 		}
 		config.Options.GlobalValues["runtime"]["buildVersion"] = version
 	}
+	if config.TestConfig.CompileTestBinary {
+		// The testing.testBinary is set to "1" when in a test.
+		// This is needed for testing.Testing() to work correctly.
+		if config.Options.GlobalValues["testing"] == nil {
+			config.Options.GlobalValues["testing"] = make(map[string]string)
+		}
+		config.Options.GlobalValues["testing"]["testBinary"] = "1"
+	}
 
 	var embedFileObjects []*compileJob
 	for _, pkg := range lprogram.Sorted() {
@@ -1054,17 +1062,6 @@ func optimizeProgram(mod llvm.Module, config *compileopts.Config) error {
 		return err
 	}
 
-	// Browsers cannot handle external functions that have type i64 because it
-	// cannot be represented exactly in JavaScript (JS only has doubles). To
-	// keep functions interoperable, pass int64 types as pointers to
-	// stack-allocated values.
-	if config.WasmAbi() == "js" {
-		err := transform.ExternalInt64AsPtr(mod, config)
-		if err != nil {
-			return err
-		}
-	}
-
 	// Optimization levels here are roughly the same as Clang, but probably not
 	// exactly.
 	optLevel, sizeLevel, inlinerThreshold := config.OptLevels()

builder/builder_test.go

@@ -60,6 +60,7 @@ func TestClangAttributes(t *testing.T) {
 		{GOOS: "darwin", GOARCH: "arm64"},
 		{GOOS: "windows", GOARCH: "amd64"},
 		{GOOS: "windows", GOARCH: "arm64"},
+		{GOOS: "wasip1", GOARCH: "wasm"},
 	} {
 		name := "GOOS=" + options.GOOS + ",GOARCH=" + options.GOARCH
 		if options.GOARCH == "arm" {

builder/config.go

@@ -1,7 +1,6 @@
 package builder
 
 import (
-	"errors"
 	"fmt"
 
 	"github.com/tinygo-org/tinygo/compileopts"
@@ -24,19 +23,14 @@ func NewConfig(options *compileopts.Options) (*compileopts.Config, error) {
 		spec.OpenOCDCommands = options.OpenOCDCommands
 	}
 
-	goroot := goenv.Get("GOROOT")
-	if goroot == "" {
-		return nil, errors.New("cannot locate $GOROOT, please set it manually")
-	}
-
-	major, minor, err := goenv.GetGorootVersion(goroot)
+	major, minor, err := goenv.GetGorootVersion()
 	if err != nil {
-		return nil, fmt.Errorf("could not read version from GOROOT (%v): %v", goroot, err)
+		return nil, err
 	}
-	if major != 1 || minor < 18 || minor > 20 {
+	if major != 1 || minor < 18 || minor > 21 {
 		// Note: when this gets updated, also update the Go compatibility matrix:
 		// https://github.com/tinygo-org/tinygo-site/blob/dev/content/docs/reference/go-compat-matrix.md
-		return nil, fmt.Errorf("requires go version 1.18 through 1.20, got go%d.%d", major, minor)
+		return nil, fmt.Errorf("requires go version 1.18 through 1.21, got go%d.%d", major, minor)
 	}
 
 	clangHeaderPath := getClangHeaderPath(goenv.Get("TINYGOROOT"))

builder/sizes_test.go

@@ -43,7 +43,7 @@ func TestBinarySize(t *testing.T) {
 		// microcontrollers
 		{"hifive1b", "examples/echo", 4612, 280, 0, 2252},
 		{"microbit", "examples/serial", 2724, 388, 8, 2256},
-		{"wioterminal", "examples/pininterrupt", 6159, 1485, 116, 6816},
+		{"wioterminal", "examples/pininterrupt", 6039, 1485, 116, 6816},
 
 		// TODO: also check wasm. Right now this is difficult, because
 		// wasm binaries are run through wasm-opt and therefore the

compileopts/config.go

@@ -492,11 +492,6 @@ func (c *Config) RelocationModel() string {
 	return "static"
 }
 
-// WasmAbi returns the WASM ABI which is specified in the target JSON file.
-func (c *Config) WasmAbi() string {
-	return c.Target.WasmAbi
-}
-
 // EmulatorName is a shorthand to get the command for this emulator, something
 // like qemu-system-arm or simavr.
 func (c *Config) EmulatorName() string {

compileopts/target.go

@@ -23,46 +23,45 @@ import (
 // https://doc.rust-lang.org/nightly/nightly-rustc/rustc_target/spec/struct.TargetOptions.html
 // https://github.com/shepmaster/rust-arduino-blink-led-no-core-with-cargo/blob/master/blink/arduino.json
 type TargetSpec struct {
-	Inherits         []string `json:"inherits"`
-	Triple           string   `json:"llvm-target"`
-	CPU              string   `json:"cpu"`
-	ABI              string   `json:"target-abi"` // rougly equivalent to -mabi= flag
-	Features         string   `json:"features"`
-	GOOS             string   `json:"goos"`
-	GOARCH           string   `json:"goarch"`
-	BuildTags        []string `json:"build-tags"`
-	GC               string   `json:"gc"`
-	Scheduler        string   `json:"scheduler"`
-	Serial           string   `json:"serial"` // which serial output to use (uart, usb, none)
-	Linker           string   `json:"linker"`
-	RTLib            string   `json:"rtlib"` // compiler runtime library (libgcc, compiler-rt)
-	Libc             string   `json:"libc"`
-	AutoStackSize    *bool    `json:"automatic-stack-size"` // Determine stack size automatically at compile time.
-	DefaultStackSize uint64   `json:"default-stack-size"`   // Default stack size if the size couldn't be determined at compile time.
-	CFlags           []string `json:"cflags"`
-	LDFlags          []string `json:"ldflags"`
-	LinkerScript     string   `json:"linkerscript"`
-	ExtraFiles       []string `json:"extra-files"`
-	RP2040BootPatch  *bool    `json:"rp2040-boot-patch"` // Patch RP2040 2nd stage bootloader checksum
-	Emulator         string   `json:"emulator"`
-	FlashCommand     string   `json:"flash-command"`
-	GDB              []string `json:"gdb"`
-	PortReset        string   `json:"flash-1200-bps-reset"`
-	SerialPort       []string `json:"serial-port"` // serial port IDs in the form "vid:pid"
-	FlashMethod      string   `json:"flash-method"`
-	FlashVolume      []string `json:"msd-volume-name"`
-	FlashFilename    string   `json:"msd-firmware-name"`
-	UF2FamilyID      string   `json:"uf2-family-id"`
-	BinaryFormat     string   `json:"binary-format"`
-	OpenOCDInterface string   `json:"openocd-interface"`
-	OpenOCDTarget    string   `json:"openocd-target"`
-	OpenOCDTransport string   `json:"openocd-transport"`
-	OpenOCDCommands  []string `json:"openocd-commands"`
-	OpenOCDVerify    *bool    `json:"openocd-verify"` // enable verify when flashing with openocd
-	JLinkDevice      string   `json:"jlink-device"`
-	CodeModel        string   `json:"code-model"`
-	RelocationModel  string   `json:"relocation-model"`
-	WasmAbi          string   `json:"wasm-abi"`
+	Inherits         []string `json:"inherits,omitempty"`
+	Triple           string   `json:"llvm-target,omitempty"`
+	CPU              string   `json:"cpu,omitempty"`
+	ABI              string   `json:"target-abi,omitempty"` // rougly equivalent to -mabi= flag
+	Features         string   `json:"features,omitempty"`
+	GOOS             string   `json:"goos,omitempty"`
+	GOARCH           string   `json:"goarch,omitempty"`
+	BuildTags        []string `json:"build-tags,omitempty"`
+	GC               string   `json:"gc,omitempty"`
+	Scheduler        string   `json:"scheduler,omitempty"`
+	Serial           string   `json:"serial,omitempty"` // which serial output to use (uart, usb, none)
+	Linker           string   `json:"linker,omitempty"`
+	RTLib            string   `json:"rtlib,omitempty"` // compiler runtime library (libgcc, compiler-rt)
+	Libc             string   `json:"libc,omitempty"`
+	AutoStackSize    *bool    `json:"automatic-stack-size,omitempty"` // Determine stack size automatically at compile time.
+	DefaultStackSize uint64   `json:"default-stack-size,omitempty"`   // Default stack size if the size couldn't be determined at compile time.
+	CFlags           []string `json:"cflags,omitempty"`
+	LDFlags          []string `json:"ldflags,omitempty"`
+	LinkerScript     string   `json:"linkerscript,omitempty"`
+	ExtraFiles       []string `json:"extra-files,omitempty"`
+	RP2040BootPatch  *bool    `json:"rp2040-boot-patch,omitempty"` // Patch RP2040 2nd stage bootloader checksum
+	Emulator         string   `json:"emulator,omitempty"`
+	FlashCommand     string   `json:"flash-command,omitempty"`
+	GDB              []string `json:"gdb,omitempty"`
+	PortReset        string   `json:"flash-1200-bps-reset,omitempty"`
+	SerialPort       []string `json:"serial-port,omitempty"` // serial port IDs in the form "vid:pid"
+	FlashMethod      string   `json:"flash-method,omitempty"`
+	FlashVolume      []string `json:"msd-volume-name,omitempty"`
+	FlashFilename    string   `json:"msd-firmware-name,omitempty"`
+	UF2FamilyID      string   `json:"uf2-family-id,omitempty"`
+	BinaryFormat     string   `json:"binary-format,omitempty"`
+	OpenOCDInterface string   `json:"openocd-interface,omitempty"`
+	OpenOCDTarget    string   `json:"openocd-target,omitempty"`
+	OpenOCDTransport string   `json:"openocd-transport,omitempty"`
+	OpenOCDCommands  []string `json:"openocd-commands,omitempty"`
+	OpenOCDVerify    *bool    `json:"openocd-verify,omitempty"` // enable verify when flashing with openocd
+	JLinkDevice      string   `json:"jlink-device,omitempty"`
+	CodeModel        string   `json:"code-model,omitempty"`
+	RelocationModel  string   `json:"relocation-model,omitempty"`
 }
 
 // overrideProperties overrides all properties that are set in child into itself using reflection.
@@ -192,12 +191,15 @@ func LoadTarget(options *Options) (*TargetSpec, error) {
 			default:
 				return nil, fmt.Errorf("invalid GOARM=%s, must be 5, 6, or 7", options.GOARM)
 			}
+		case "wasm":
+			llvmarch = "wasm32"
 		default:
 			llvmarch = options.GOARCH
 		}
 		llvmvendor := "unknown"
 		llvmos := options.GOOS
-		if llvmos == "darwin" {
+		switch llvmos {
+		case "darwin":
 			// Use macosx* instead of darwin, otherwise darwin/arm64 will refer
 			// to iOS!
 			llvmos = "macosx10.12.0"
@@ -208,6 +210,8 @@ func LoadTarget(options *Options) (*TargetSpec, error) {
 				llvmos = "macosx11.0.0"
 			}
 			llvmvendor = "apple"
+		case "wasip1":
+			llvmos = "wasi"
 		}
 		// Target triples (which actually have four components, but are called
 		// triples for historical reasons) have the form:
@@ -278,6 +282,15 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 	case "arm64":
 		spec.CPU = "generic"
 		spec.Features = "+neon"
+	case "wasm":
+		spec.CPU = "generic"
+		spec.Features = "+bulk-memory,+nontrapping-fptoint,+sign-ext"
+		spec.BuildTags = append(spec.BuildTags, "tinygo.wasm")
+		spec.CFlags = append(spec.CFlags,
+			"-mbulk-memory",
+			"-mnontrapping-fptoint",
+			"-msign-ext",
+		)
 	}
 	if goos == "darwin" {
 		spec.Linker = "ld.lld"
@@ -321,6 +334,22 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 			"--no-insert-timestamp",
 			"--no-dynamicbase",
 		)
+	} else if goos == "wasip1" {
+		spec.GC = "" // use default GC
+		spec.Scheduler = "asyncify"
+		spec.Linker = "wasm-ld"
+		spec.RTLib = "compiler-rt"
+		spec.Libc = "wasi-libc"
+		spec.DefaultStackSize = 1024 * 16 // 16kB
+		spec.LDFlags = append(spec.LDFlags,
+			"--stack-first",
+			"--no-demangle",
+		)
+		spec.Emulator = "wasmtime --mapdir=/tmp::{tmpDir} {}"
+		spec.ExtraFiles = append(spec.ExtraFiles,
+			"src/runtime/asm_tinygowasm.S",
+			"src/internal/task/task_asyncify_wasm.S",
+		)
 	} else {
 		spec.LDFlags = append(spec.LDFlags, "-no-pie", "-Wl,--gc-sections") // WARNING: clang < 5.0 requires -nopie
 	}

compiler/calls.go

@@ -36,7 +36,11 @@ const (
 // createRuntimeCallCommon creates a runtime call. Use createRuntimeCall or
 // createRuntimeInvoke instead.
 func (b *builder) createRuntimeCallCommon(fnName string, args []llvm.Value, name string, isInvoke bool) llvm.Value {
-	fn := b.program.ImportedPackage("runtime").Members[fnName].(*ssa.Function)
+	member := b.program.ImportedPackage("runtime").Members[fnName]
+	if member == nil {
+		panic("unknown runtime call: " + fnName)
+	}
+	fn := member.(*ssa.Function)
 	fnType, llvmFn := b.getFunction(fn)
 	if llvmFn.IsNil() {
 		panic("trying to call non-existent function: " + fn.RelString(nil))

compiler/compiler.go

@@ -1600,6 +1600,45 @@ func (b *builder) createBuiltin(argTypes []types.Type, argValues []llvm.Value, c
 		cplx = b.CreateInsertValue(cplx, r, 0, "")
 		cplx = b.CreateInsertValue(cplx, i, 1, "")
 		return cplx, nil
+	case "clear":
+		value := argValues[0]
+		switch typ := argTypes[0].Underlying().(type) {
+		case *types.Slice:
+			elementType := b.getLLVMType(typ.Elem())
+			elementSize := b.targetData.TypeAllocSize(elementType)
+			elementAlign := b.targetData.ABITypeAlignment(elementType)
+
+			// The pointer to the data to be cleared.
+			llvmBuf := b.CreateExtractValue(value, 0, "buf")
+			if llvmBuf.Type() != b.i8ptrType { // compatibility with LLVM 14
+				llvmBuf = b.CreateBitCast(llvmBuf, b.i8ptrType, "")
+			}
+
+			// The length (in bytes) to be cleared.
+			llvmLen := b.CreateExtractValue(value, 1, "len")
+			llvmLen = b.CreateMul(llvmLen, llvm.ConstInt(llvmLen.Type(), elementSize, false), "")
+
+			// Do the clear operation using the LLVM memset builtin.
+			// This is also correct for nil slices: in those cases, len will be
+			// 0 which means the memset call is a no-op (according to the LLVM
+			// LangRef).
+			memset := b.getMemsetFunc()
+			call := b.createCall(memset.GlobalValueType(), memset, []llvm.Value{
+				llvmBuf, // dest
+				llvm.ConstInt(b.ctx.Int8Type(), 0, false), // val
+				llvmLen, // len
+				llvm.ConstInt(b.ctx.Int1Type(), 0, false), // isVolatile
+			}, "")
+			call.AddCallSiteAttribute(1, b.ctx.CreateEnumAttribute(llvm.AttributeKindID("align"), uint64(elementAlign)))
+
+			return llvm.Value{}, nil
+		case *types.Map:
+			m := argValues[0]
+			b.createMapClear(m)
+			return llvm.Value{}, nil
+		default:
+			return llvm.Value{}, b.makeError(pos, "unsupported type in clear builtin: "+typ.String())
+		}
 	case "copy":
 		dst := argValues[0]
 		src := argValues[1]
@@ -1637,6 +1676,24 @@ func (b *builder) createBuiltin(argTypes []types.Type, argValues []llvm.Value, c
 			llvmLen = b.CreateZExt(llvmLen, b.intType, "len.int")
 		}
 		return llvmLen, nil
+	case "min", "max":
+		// min and max builtins, added in Go 1.21.
+		// We can simply reuse the existing binop comparison code, which has all
+		// the edge cases figured out already.
+		tok := token.LSS
+		if callName == "max" {
+			tok = token.GTR
+		}
+		result := argValues[0]
+		typ := argTypes[0]
+		for _, arg := range argValues[1:] {
+			cmp, err := b.createBinOp(tok, typ, typ, result, arg, pos)
+			if err != nil {
+				return result, err
+			}
+			result = b.CreateSelect(cmp, result, arg, "")
+		}
+		return result, nil
 	case "print", "println":
 		for i, value := range argValues {
 			if i >= 1 && callName == "println" {

compiler/compiler_test.go

@@ -29,7 +29,7 @@ func TestCompiler(t *testing.T) {
 	t.Parallel()
 
 	// Determine Go minor version (e.g. 16 in go1.16.3).
-	_, goMinor, err := goenv.GetGorootVersion(goenv.Get("GOROOT"))
+	_, goMinor, err := goenv.GetGorootVersion()
 	if err != nil {
 		t.Fatal("could not read Go version:", err)
 	}
@@ -54,6 +54,9 @@ func TestCompiler(t *testing.T) {
 	if goMinor >= 20 {
 		tests = append(tests, testCase{"go1.20.go", "", ""})
 	}
+	if goMinor >= 21 {
+		tests = append(tests, testCase{"go1.21.go", "", ""})
+	}
 
 	for _, tc := range tests {
 		name := tc.file

compiler/interface.go

@@ -128,6 +128,15 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 		hasMethodSet = false
 	}
 
+	var numMethods int
+	if hasMethodSet {
+		for i := 0; i < ms.Len(); i++ {
+			if ms.At(i).Obj().Exported() {
+				numMethods++
+			}
+		}
+	}
+
 	// Short-circuit all the global pointer logic here for pointers to pointers.
 	if typ, ok := typ.(*types.Pointer); ok {
 		if _, ok := typ.Elem().(*types.Pointer); ok {
@@ -277,11 +286,11 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 			}
 			pkgPathPtr := c.pkgPathPtr(pkgpath)
 			typeFields = []llvm.Value{
-				llvm.ConstInt(c.ctx.Int16Type(), uint64(ms.Len()), false), // numMethods
-				c.getTypeCode(types.NewPointer(typ)),                      // ptrTo
-				c.getTypeCode(typ.Underlying()),                           // underlying
-				pkgPathPtr,                                                // pkgpath pointer
-				c.ctx.ConstString(pkgname+"."+name+"\x00", false),         // name
+				llvm.ConstInt(c.ctx.Int16Type(), uint64(numMethods), false), // numMethods
+				c.getTypeCode(types.NewPointer(typ)),                        // ptrTo
+				c.getTypeCode(typ.Underlying()),                             // underlying
+				pkgPathPtr,                                                  // pkgpath pointer
+				c.ctx.ConstString(pkgname+"."+name+"\x00", false),           // name
 			}
 			metabyte |= 1 << 5 // "named" flag
 		case *types.Chan:
@@ -308,7 +317,7 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 			}
 		case *types.Pointer:
 			typeFields = []llvm.Value{
-				llvm.ConstInt(c.ctx.Int16Type(), uint64(ms.Len()), false), // numMethods
+				llvm.ConstInt(c.ctx.Int16Type(), uint64(numMethods), false), // numMethods
 				c.getTypeCode(typ.Elem()),
 			}
 		case *types.Array:
@@ -337,8 +346,8 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 			llvmStructType := c.getLLVMType(typ)
 			size := c.targetData.TypeStoreSize(llvmStructType)
 			typeFields = []llvm.Value{
-				llvm.ConstInt(c.ctx.Int16Type(), uint64(ms.Len()), false), // numMethods
-				c.getTypeCode(types.NewPointer(typ)),                      // ptrTo
+				llvm.ConstInt(c.ctx.Int16Type(), uint64(numMethods), false), // numMethods
+				c.getTypeCode(types.NewPointer(typ)),                        // ptrTo
 				pkgPathPtr,
 				llvm.ConstInt(c.ctx.Int32Type(), uint64(size), false),            // size
 				llvm.ConstInt(c.ctx.Int16Type(), uint64(typ.NumFields()), false), // numFields

compiler/intrinsics.go

@@ -70,15 +70,7 @@ func (b *builder) createMemoryCopyImpl() {
 // regular libc memset calls if they aren't optimized out in a different way.
 func (b *builder) createMemoryZeroImpl() {
 	b.createFunctionStart(true)
-	fnName := "llvm.memset.p0.i" + strconv.Itoa(b.uintptrType.IntTypeWidth())
-	if llvmutil.Major() < 15 { // compatibility with LLVM 14
-		fnName = "llvm.memset.p0i8.i" + strconv.Itoa(b.uintptrType.IntTypeWidth())
-	}
-	llvmFn := b.mod.NamedFunction(fnName)
-	if llvmFn.IsNil() {
-		fnType := llvm.FunctionType(b.ctx.VoidType(), []llvm.Type{b.i8ptrType, b.ctx.Int8Type(), b.uintptrType, b.ctx.Int1Type()}, false)
-		llvmFn = llvm.AddFunction(b.mod, fnName, fnType)
-	}
+	llvmFn := b.getMemsetFunc()
 	params := []llvm.Value{
 		b.getValue(b.fn.Params[0], getPos(b.fn)),
 		llvm.ConstInt(b.ctx.Int8Type(), 0, false),
@@ -89,6 +81,20 @@ func (b *builder) createMemoryZeroImpl() {
 	b.CreateRetVoid()
 }
 
+// Return the llvm.memset.p0.i8 function declaration.
+func (c *compilerContext) getMemsetFunc() llvm.Value {
+	fnName := "llvm.memset.p0.i" + strconv.Itoa(c.uintptrType.IntTypeWidth())
+	if llvmutil.Major() < 15 { // compatibility with LLVM 14
+		fnName = "llvm.memset.p0i8.i" + strconv.Itoa(c.uintptrType.IntTypeWidth())
+	}
+	llvmFn := c.mod.NamedFunction(fnName)
+	if llvmFn.IsNil() {
+		fnType := llvm.FunctionType(c.ctx.VoidType(), []llvm.Type{c.i8ptrType, c.ctx.Int8Type(), c.uintptrType, c.ctx.Int1Type()}, false)
+		llvmFn = llvm.AddFunction(c.mod, fnName, fnType)
+	}
+	return llvmFn
+}
+
 // createKeepAlive creates the runtime.KeepAlive function. It is implemented
 // using inline assembly.
 func (b *builder) createKeepAliveImpl() {

compiler/map.go

@@ -185,6 +185,11 @@ func (b *builder) createMapDelete(keyType types.Type, m, key llvm.Value, pos tok
 	}
 }
 
+// Clear the given map.
+func (b *builder) createMapClear(m llvm.Value) {
+	b.createRuntimeCall("hashmapClear", []llvm.Value{m}, "")
+}
+
 // createMapIteratorNext lowers the *ssa.Next instruction for iterating over a
 // map. It returns a tuple of {bool, key, value} with the result of the
 // iteration.

compiler/symbol.go

@@ -23,9 +23,9 @@ import (
 // The linkName value contains a valid link name, even if //go:linkname is not
 // present.
 type functionInfo struct {
-	module     string     // go:wasm-module
-	importName string     // go:linkname, go:export - The name the developer assigns
-	linkName   string     // go:linkname, go:export - The name that we map for the particular module -> importName
+	wasmModule string     // go:wasm-module
+	wasmName   string     // wasm-export-name or wasm-import-name in the IR
+	linkName   string     // go:linkname, go:export - the IR function name
 	section    string     // go:section - object file section name
 	exported   bool       // go:export, CGo
 	interrupt  bool       // go:interrupt
@@ -194,20 +194,14 @@ func (c *compilerContext) getFunction(fn *ssa.Function) (llvm.Type, llvm.Value)
 	// External/exported functions may not retain pointer values.
 	// https://golang.org/cmd/cgo/#hdr-Passing_pointers
 	if info.exported {
-		if c.archFamily() == "wasm32" {
+		if c.archFamily() == "wasm32" && len(fn.Blocks) == 0 {
 			// We need to add the wasm-import-module and the wasm-import-name
 			// attributes.
-			module := info.module
-			if module == "" {
-				module = "env"
+			if info.wasmModule != "" {
+				llvmFn.AddFunctionAttr(c.ctx.CreateStringAttribute("wasm-import-module", info.wasmModule))
 			}
-			llvmFn.AddFunctionAttr(c.ctx.CreateStringAttribute("wasm-import-module", module))
 
-			name := info.importName
-			if name == "" {
-				name = info.linkName
-			}
-			llvmFn.AddFunctionAttr(c.ctx.CreateStringAttribute("wasm-import-name", name))
+			llvmFn.AddFunctionAttr(c.ctx.CreateStringAttribute("wasm-import-name", info.wasmName))
 		}
 		nocaptureKind := llvm.AttributeKindID("nocapture")
 		nocapture := c.ctx.CreateEnumAttribute(nocaptureKind, 0)
@@ -260,10 +254,6 @@ func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
 		return
 	}
 	if decl, ok := f.Syntax().(*ast.FuncDecl); ok && decl.Doc != nil {
-
-		// Our importName for a wasm module (if we are compiling to wasm), or llvm link name
-		var importName string
-
 		for _, comment := range decl.Doc.List {
 			text := comment.Text
 			if strings.HasPrefix(text, "//export ") {
@@ -281,7 +271,8 @@ func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
 					continue
 				}
 
-				importName = parts[1]
+				info.linkName = parts[1]
+				info.wasmName = info.linkName
 				info.exported = true
 			case "//go:interrupt":
 				if hasUnsafeImport(f.Pkg.Pkg) {
@@ -289,10 +280,11 @@ func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
 				}
 			case "//go:wasm-module":
 				// Alternative comment for setting the import module.
+				// This is deprecated, use //go:wasmimport instead.
 				if len(parts) != 2 {
 					continue
 				}
-				info.module = parts[1]
+				info.wasmModule = parts[1]
 			case "//go:wasmimport":
 				// Import a WebAssembly function, for example a WASI function.
 				// Original proposal: https://github.com/golang/go/issues/38248
@@ -302,8 +294,8 @@ func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
 				}
 				c.checkWasmImport(f, comment.Text)
 				info.exported = true
-				info.module = parts[1]
-				info.importName = parts[2]
+				info.wasmModule = parts[1]
+				info.wasmName = parts[2]
 			case "//go:inline":
 				info.inline = inlineHint
 			case "//go:noinline":
@@ -347,17 +339,6 @@ func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
 				}
 			}
 		}
-
-		// Set the importName for our exported function if we have one
-		if importName != "" {
-			if info.module == "" {
-				info.linkName = importName
-			} else {
-				// WebAssembly import
-				info.importName = importName
-			}
-		}
-
 	}
 }
 
@@ -367,7 +348,7 @@ func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
 // The list of allowed types is based on this proposal:
 // https://github.com/golang/go/issues/59149
 func (c *compilerContext) checkWasmImport(f *ssa.Function, pragma string) {
-	if c.pkg.Path() == "runtime" {
+	if c.pkg.Path() == "runtime" || c.pkg.Path() == "syscall/js" {
 		// The runtime is a special case. Allow all kinds of parameters
 		// (importantly, including pointers).
 		return

compiler/testdata/go1.21.go

@@ -0,0 +1,65 @@
+package main
+
+func min1(a int) int {
+	return min(a)
+}
+
+func min2(a, b int) int {
+	return min(a, b)
+}
+
+func min3(a, b, c int) int {
+	return min(a, b, c)
+}
+
+func min4(a, b, c, d int) int {
+	return min(a, b, c, d)
+}
+
+func minUint8(a, b uint8) uint8 {
+	return min(a, b)
+}
+
+func minUnsigned(a, b uint) uint {
+	return min(a, b)
+}
+
+func minFloat32(a, b float32) float32 {
+	return min(a, b)
+}
+
+func minFloat64(a, b float64) float64 {
+	return min(a, b)
+}
+
+func minString(a, b string) string {
+	return min(a, b)
+}
+
+func maxInt(a, b int) int {
+	return max(a, b)
+}
+
+func maxUint(a, b uint) uint {
+	return max(a, b)
+}
+
+func maxFloat32(a, b float32) float32 {
+	return max(a, b)
+}
+
+func maxString(a, b string) string {
+	return max(a, b)
+}
+
+func clearSlice(s []int) {
+	clear(s)
+}
+
+func clearZeroSizedSlice(s []struct{}) {
+	clear(s)
+}
+
+func clearMap(m map[string]int) {
+	clear(m)
+}

compiler/testdata/go1.21.ll

@@ -0,0 +1,179 @@
+; ModuleID = 'go1.21.go'
+source_filename = "go1.21.go"
+target datalayout = "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-n32:64-S128-ni:1:10:20"
+target triple = "wasm32-unknown-wasi"
+
+%runtime._string = type { ptr, i32 }
+
+; Function Attrs: allockind("alloc,zeroed") allocsize(0)
+declare noalias nonnull ptr @runtime.alloc(i32, ptr, ptr) #0
+
+declare void @runtime.trackPointer(ptr nocapture readonly, ptr, ptr) #1
+
+; Function Attrs: nounwind
+define hidden void @main.init(ptr %context) unnamed_addr #2 {
+entry:
+  ret void
+}
+
+; Function Attrs: nounwind
+define hidden i32 @main.min1(i32 %a, ptr %context) unnamed_addr #2 {
+entry:
+  ret i32 %a
+}
+
+; Function Attrs: nounwind
+define hidden i32 @main.min2(i32 %a, i32 %b, ptr %context) unnamed_addr #2 {
+entry:
+  %0 = call i32 @llvm.smin.i32(i32 %a, i32 %b)
+  ret i32 %0
+}
+
+; Function Attrs: nounwind
+define hidden i32 @main.min3(i32 %a, i32 %b, i32 %c, ptr %context) unnamed_addr #2 {
+entry:
+  %0 = call i32 @llvm.smin.i32(i32 %a, i32 %b)
+  %1 = call i32 @llvm.smin.i32(i32 %0, i32 %c)
+  ret i32 %1
+}
+
+; Function Attrs: nounwind
+define hidden i32 @main.min4(i32 %a, i32 %b, i32 %c, i32 %d, ptr %context) unnamed_addr #2 {
+entry:
+  %0 = call i32 @llvm.smin.i32(i32 %a, i32 %b)
+  %1 = call i32 @llvm.smin.i32(i32 %0, i32 %c)
+  %2 = call i32 @llvm.smin.i32(i32 %1, i32 %d)
+  ret i32 %2
+}
+
+; Function Attrs: nounwind
+define hidden i8 @main.minUint8(i8 %a, i8 %b, ptr %context) unnamed_addr #2 {
+entry:
+  %0 = call i8 @llvm.umin.i8(i8 %a, i8 %b)
+  ret i8 %0
+}
+
+; Function Attrs: nounwind
+define hidden i32 @main.minUnsigned(i32 %a, i32 %b, ptr %context) unnamed_addr #2 {
+entry:
+  %0 = call i32 @llvm.umin.i32(i32 %a, i32 %b)
+  ret i32 %0
+}
+
+; Function Attrs: nounwind
+define hidden float @main.minFloat32(float %a, float %b, ptr %context) unnamed_addr #2 {
+entry:
+  %0 = fcmp olt float %a, %b
+  %1 = select i1 %0, float %a, float %b
+  ret float %1
+}
+
+; Function Attrs: nounwind
+define hidden double @main.minFloat64(double %a, double %b, ptr %context) unnamed_addr #2 {
+entry:
+  %0 = fcmp olt double %a, %b
+  %1 = select i1 %0, double %a, double %b
+  ret double %1
+}
+
+; Function Attrs: nounwind
+define hidden %runtime._string @main.minString(ptr %a.data, i32 %a.len, ptr %b.data, i32 %b.len, ptr %context) unnamed_addr #2 {
+entry:
+  %0 = insertvalue %runtime._string zeroinitializer, ptr %a.data, 0
+  %1 = insertvalue %runtime._string %0, i32 %a.len, 1
+  %2 = insertvalue %runtime._string zeroinitializer, ptr %b.data, 0
+  %3 = insertvalue %runtime._string %2, i32 %b.len, 1
+  %stackalloc = alloca i8, align 1
+  %4 = call i1 @runtime.stringLess(ptr %a.data, i32 %a.len, ptr %b.data, i32 %b.len, ptr undef) #5
+  %5 = select i1 %4, %runtime._string %1, %runtime._string %3
+  %6 = extractvalue %runtime._string %5, 0
+  call void @runtime.trackPointer(ptr %6, ptr nonnull %stackalloc, ptr undef) #5
+  ret %runtime._string %5
+}
+
+declare i1 @runtime.stringLess(ptr, i32, ptr, i32, ptr) #1
+
+; Function Attrs: nounwind
+define hidden i32 @main.maxInt(i32 %a, i32 %b, ptr %context) unnamed_addr #2 {
+entry:
+  %0 = call i32 @llvm.smax.i32(i32 %a, i32 %b)
+  ret i32 %0
+}
+
+; Function Attrs: nounwind
+define hidden i32 @main.maxUint(i32 %a, i32 %b, ptr %context) unnamed_addr #2 {
+entry:
+  %0 = call i32 @llvm.umax.i32(i32 %a, i32 %b)
+  ret i32 %0
+}
+
+; Function Attrs: nounwind
+define hidden float @main.maxFloat32(float %a, float %b, ptr %context) unnamed_addr #2 {
+entry:
+  %0 = fcmp ogt float %a, %b
+  %1 = select i1 %0, float %a, float %b
+  ret float %1
+}
+
+; Function Attrs: nounwind
+define hidden %runtime._string @main.maxString(ptr %a.data, i32 %a.len, ptr %b.data, i32 %b.len, ptr %context) unnamed_addr #2 {
+entry:
+  %0 = insertvalue %runtime._string zeroinitializer, ptr %a.data, 0
+  %1 = insertvalue %runtime._string %0, i32 %a.len, 1
+  %2 = insertvalue %runtime._string zeroinitializer, ptr %b.data, 0
+  %3 = insertvalue %runtime._string %2, i32 %b.len, 1
+  %stackalloc = alloca i8, align 1
+  %4 = call i1 @runtime.stringLess(ptr %b.data, i32 %b.len, ptr %a.data, i32 %a.len, ptr undef) #5
+  %5 = select i1 %4, %runtime._string %1, %runtime._string %3
+  %6 = extractvalue %runtime._string %5, 0
+  call void @runtime.trackPointer(ptr %6, ptr nonnull %stackalloc, ptr undef) #5
+  ret %runtime._string %5
+}
+
+; Function Attrs: nounwind
+define hidden void @main.clearSlice(ptr %s.data, i32 %s.len, i32 %s.cap, ptr %context) unnamed_addr #2 {
+entry:
+  %0 = shl i32 %s.len, 2
+  call void @llvm.memset.p0.i32(ptr align 4 %s.data, i8 0, i32 %0, i1 false)
+  ret void
+}
+
+; Function Attrs: argmemonly nocallback nofree nounwind willreturn writeonly
+declare void @llvm.memset.p0.i32(ptr nocapture writeonly, i8, i32, i1 immarg) #3
+
+; Function Attrs: nounwind
+define hidden void @main.clearZeroSizedSlice(ptr %s.data, i32 %s.len, i32 %s.cap, ptr %context) unnamed_addr #2 {
+entry:
+  ret void
+}
+
+; Function Attrs: nounwind
+define hidden void @main.clearMap(ptr dereferenceable_or_null(40) %m, ptr %context) unnamed_addr #2 {
+entry:
+  call void @runtime.hashmapClear(ptr %m, ptr undef) #5
+  ret void
+}
+
+declare void @runtime.hashmapClear(ptr dereferenceable_or_null(40), ptr) #1
+
+; Function Attrs: nocallback nofree nosync nounwind readnone speculatable willreturn
+declare i32 @llvm.smin.i32(i32, i32) #4
+
+; Function Attrs: nocallback nofree nosync nounwind readnone speculatable willreturn
+declare i8 @llvm.umin.i8(i8, i8) #4
+
+; Function Attrs: nocallback nofree nosync nounwind readnone speculatable willreturn
+declare i32 @llvm.umin.i32(i32, i32) #4
+
+; Function Attrs: nocallback nofree nosync nounwind readnone speculatable willreturn
+declare i32 @llvm.smax.i32(i32, i32) #4
+
+; Function Attrs: nocallback nofree nosync nounwind readnone speculatable willreturn
+declare i32 @llvm.umax.i32(i32, i32) #4
+
+attributes #0 = { allockind("alloc,zeroed") allocsize(0) "alloc-family"="runtime.alloc" "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
+attributes #1 = { "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
+attributes #2 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
+attributes #3 = { argmemonly nocallback nofree nounwind willreturn writeonly }
+attributes #4 = { nocallback nofree nosync nounwind readnone speculatable willreturn }
+attributes #5 = { nounwind }

compiler/testdata/interface.ll

@@ -9,7 +9,7 @@ target triple = "wasm32-unknown-wasi"
 @"reflect/types.type:basic:int" = linkonce_odr constant { i8, ptr } { i8 -62, ptr @"reflect/types.type:pointer:basic:int" }, align 4
 @"reflect/types.type:pointer:basic:int" = linkonce_odr constant { i8, i16, ptr } { i8 -43, i16 0, ptr @"reflect/types.type:basic:int" }, align 4
 @"reflect/types.type:pointer:named:error" = linkonce_odr constant { i8, i16, ptr } { i8 -43, i16 0, ptr @"reflect/types.type:named:error" }, align 4
-@"reflect/types.type:named:error" = linkonce_odr constant { i8, i16, ptr, ptr, ptr, [7 x i8] } { i8 116, i16 1, ptr @"reflect/types.type:pointer:named:error", ptr @"reflect/types.type:interface:{Error:func:{}{basic:string}}", ptr @"reflect/types.type.pkgpath.empty", [7 x i8] c".error\00" }, align 4
+@"reflect/types.type:named:error" = linkonce_odr constant { i8, i16, ptr, ptr, ptr, [7 x i8] } { i8 116, i16 0, ptr @"reflect/types.type:pointer:named:error", ptr @"reflect/types.type:interface:{Error:func:{}{basic:string}}", ptr @"reflect/types.type.pkgpath.empty", [7 x i8] c".error\00" }, align 4
 @"reflect/types.type.pkgpath.empty" = linkonce_odr unnamed_addr constant [1 x i8] zeroinitializer, align 1
 @"reflect/types.type:interface:{Error:func:{}{basic:string}}" = linkonce_odr constant { i8, ptr } { i8 84, ptr @"reflect/types.type:pointer:interface:{Error:func:{}{basic:string}}" }, align 4
 @"reflect/types.type:pointer:interface:{Error:func:{}{basic:string}}" = linkonce_odr constant { i8, i16, ptr } { i8 -43, i16 0, ptr @"reflect/types.type:interface:{Error:func:{}{basic:string}}" }, align 4

compiler/testdata/pragma.go

@@ -62,6 +62,19 @@ func exportedFunctionInSection() {
 //go:wasmimport modulename import1
 func declaredImport()
 
+// Legacy way of importing a function.
+//
+//go:wasm-module foobar
+//export imported
+func foobarImport()
+
+// The wasm-module pragma is not functional here, but it should be safe.
+//
+//go:wasm-module foobar
+//export exported
+func foobarExportModule() {
+}
+
 // This function should not: it's only a declaration and not a definition.
 //
 //go:section .special_function_section

compiler/testdata/pragma.ll

@@ -6,7 +6,7 @@ target triple = "wasm32-unknown-wasi"
 @extern_global = external global [0 x i8], align 1
 @main.alignedGlobal = hidden global [4 x i32] zeroinitializer, align 32
 @main.alignedGlobal16 = hidden global [4 x i32] zeroinitializer, align 16
-@llvm.used = appending global [2 x ptr] [ptr @extern_func, ptr @exportedFunctionInSection]
+@llvm.used = appending global [3 x ptr] [ptr @extern_func, ptr @exportedFunctionInSection, ptr @exported]
 @main.globalInSection = hidden global i32 0, section ".special_global_section", align 4
 @undefinedGlobalNotInSection = external global i32, align 4
 @main.multipleGlobalPragmas = hidden global i32 0, section ".global_section", align 1024
@@ -62,13 +62,23 @@ entry:
 
 declare void @main.declaredImport() #7
 
+declare void @imported() #8
+
+; Function Attrs: nounwind
+define void @exported() #9 {
+entry:
+  ret void
+}
+
 declare void @main.undefinedFunctionNotInSection(ptr) #1
 
 attributes #0 = { allockind("alloc,zeroed") allocsize(0) "alloc-family"="runtime.alloc" "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
 attributes #1 = { "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
 attributes #2 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
-attributes #3 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-export-name"="extern_func" "wasm-import-module"="env" "wasm-import-name"="extern_func" }
+attributes #3 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-export-name"="extern_func" }
 attributes #4 = { inlinehint nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
 attributes #5 = { noinline nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
-attributes #6 = { noinline nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-export-name"="exportedFunctionInSection" "wasm-import-module"="env" "wasm-import-name"="exportedFunctionInSection" }
+attributes #6 = { noinline nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-export-name"="exportedFunctionInSection" }
 attributes #7 = { "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-import-module"="modulename" "wasm-import-name"="import1" }
+attributes #8 = { "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-import-module"="foobar" "wasm-import-name"="imported" }
+attributes #9 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-export-name"="exported" }

go.mod

@@ -14,7 +14,7 @@ require (
 	github.com/mattn/go-colorable v0.1.8
 	github.com/mattn/go-tty v0.0.4
 	github.com/sigurn/crc16 v0.0.0-20211026045750-20ab5afb07e3
-	go.bug.st/serial v1.3.5
+	go.bug.st/serial v1.6.0
 	golang.org/x/sys v0.4.0
 	golang.org/x/tools v0.5.1-0.20230114154351-e035d0c426c8
 	gopkg.in/yaml.v2 v2.4.0

go.sum

@@ -12,6 +12,8 @@ github.com/chromedp/sysutil v1.0.0/go.mod h1:kgWmDdq8fTzXYcKIBqIYvRRTnYb9aNS9moA
 github.com/creack/goselect v0.1.2 h1:2DNy14+JPjRBgPzAd1thbQp4BSIihxcBf0IXhQXDRa0=
 github.com/creack/goselect v0.1.2/go.mod h1:a/NhLweNvqIYMuxcMOuWY516Cimucms3DglDzQP3hKY=
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/deadprogram/go-serial v0.0.0-20230717164825-4529b3232919 h1:Hi7G1bCG70NwlyqGswJKEHoIi4hJVN1SsmfwZ+DQHtw=
+github.com/deadprogram/go-serial v0.0.0-20230717164825-4529b3232919/go.mod h1:UABfsluHAiaNI+La2iESysd9Vetq7VRdpxvjx7CmmOE=
 github.com/gobwas/httphead v0.1.0 h1:exrUm0f4YX0L7EBwZHuCF4GDp8aJfVeBrlLQrs6NqWU=
 github.com/gobwas/httphead v0.1.0/go.mod h1:O/RXo79gxV8G+RqlR/otEwx4Q36zl9rqC5u12GKvMCM=
 github.com/gobwas/pool v0.2.1 h1:xfeeEhW7pwmX8nuLVlqbzVc7udMDrwetjEv+TZIz1og=
@@ -46,8 +48,8 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/sigurn/crc16 v0.0.0-20211026045750-20ab5afb07e3 h1:aQKxg3+2p+IFXXg97McgDGT5zcMrQoi0EICZs8Pgchs=
 github.com/sigurn/crc16 v0.0.0-20211026045750-20ab5afb07e3/go.mod h1:9/etS5gpQq9BJsJMWg1wpLbfuSnkm8dPF6FdW2JXVhA=
 github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
-go.bug.st/serial v1.3.5 h1:k50SqGZCnHZ2MiBQgzccXWG+kd/XpOs1jUljpDDKzaE=
-go.bug.st/serial v1.3.5/go.mod h1:z8CesKorE90Qr/oRSJiEuvzYRKol9r/anJZEb5kt304=
+go.bug.st/serial v1.6.0 h1:mAbRGN4cKE2J5gMwsMHC2KQisdLRQssO9WSM+rbZJ8A=
+go.bug.st/serial v1.6.0/go.mod h1:UABfsluHAiaNI+La2iESysd9Vetq7VRdpxvjx7CmmOE=
 golang.org/x/mod v0.7.0 h1:LapD9S96VoQRhi/GrNTqeBJFrUjs5UHCAtTlgwA5oZA=
 golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20191008105621-543471e840be/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

goenv/goenv.go

@@ -4,15 +4,16 @@ package goenv
 
 import (
 	"bytes"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io/fs"
 	"os"
 	"os/exec"
-	"os/user"
 	"path/filepath"
 	"runtime"
 	"strings"
+	"sync"
 )
 
 // Keys is a slice of all available environment variable keys.
@@ -37,6 +38,53 @@ func init() {
 // directory.
 var TINYGOROOT string
 
+// Variables read from a `go env` command invocation.
+var goEnvVars struct {
+	GOPATH    string
+	GOROOT    string
+	GOVERSION string
+}
+
+var goEnvVarsOnce sync.Once
+var goEnvVarsErr error // error returned from cmd.Run
+
+// Make sure goEnvVars is fresh. This can be called multiple times, the first
+// time will update all environment variables in goEnvVars.
+func readGoEnvVars() error {
+	goEnvVarsOnce.Do(func() {
+		cmd := exec.Command("go", "env", "-json", "GOPATH", "GOROOT", "GOVERSION")
+		output, err := cmd.Output()
+		if err != nil {
+			// Check for "command not found" error.
+			if execErr, ok := err.(*exec.Error); ok {
+				goEnvVarsErr = fmt.Errorf("could not find '%s' command: %w", execErr.Name, execErr.Err)
+				return
+			}
+			// It's perhaps a bit ugly to handle this error here, but I couldn't
+			// think of a better place further up in the call chain.
+			if exitErr, ok := err.(*exec.ExitError); ok && exitErr.ExitCode() != 0 {
+				if len(exitErr.Stderr) != 0 {
+					// The 'go' command exited with an error message. Print that
+					// message and exit, so we behave in a similar way.
+					os.Stderr.Write(exitErr.Stderr)
+					os.Exit(exitErr.ExitCode())
+				}
+			}
+			// Other errors. Not sure whether there are any, but just in case.
+			goEnvVarsErr = err
+			return
+		}
+		err = json.Unmarshal(output, &goEnvVars)
+		if err != nil {
+			// This should never happen if we have a sane Go toolchain
+			// installed.
+			goEnvVarsErr = fmt.Errorf("unexpected error while unmarshalling `go env` output: %w", err)
+		}
+	})
+
+	return goEnvVarsErr
+}
+
 // Get returns a single environment variable, possibly calculating it on-demand.
 // The empty string is returned for unknown environment variables.
 func Get(name string) string {
@@ -70,15 +118,11 @@ func Get(name string) string {
 		// especially when floating point instructions are involved.
 		return "6"
 	case "GOROOT":
-		return getGoroot()
+		readGoEnvVars()
+		return goEnvVars.GOROOT
 	case "GOPATH":
-		if dir := os.Getenv("GOPATH"); dir != "" {
-			return dir
-		}
-
-		// fallback
-		home := getHomeDir()
-		return filepath.Join(home, "go")
+		readGoEnvVars()
+		return goEnvVars.GOPATH
 	case "GOCACHE":
 		// Get the cache directory, usually ~/.cache/tinygo
 		dir, err := os.UserCacheDir()
@@ -240,93 +284,3 @@ func isSourceDir(root string) bool {
 	_, err = os.Stat(filepath.Join(root, "src/device/arm/arm.go"))
 	return err == nil
 }
-
-func getHomeDir() string {
-	u, err := user.Current()
-	if err != nil {
-		panic("cannot get current user: " + err.Error())
-	}
-	if u.HomeDir == "" {
-		// This is very unlikely, so panic here.
-		// Not the nicest solution, however.
-		panic("could not find home directory")
-	}
-	return u.HomeDir
-}
-
-// getGoroot returns an appropriate GOROOT from various sources. If it can't be
-// found, it returns an empty string.
-func getGoroot() string {
-	// An explicitly set GOROOT always has preference.
-	goroot := os.Getenv("GOROOT")
-	if goroot != "" {
-		// Convert to the standard GOROOT being referenced, if it's a TinyGo cache.
-		return getStandardGoroot(goroot)
-	}
-
-	// Check for the location of the 'go' binary and base GOROOT on that.
-	binpath, err := exec.LookPath("go")
-	if err == nil {
-		binpath, err = filepath.EvalSymlinks(binpath)
-		if err == nil {
-			goroot := filepath.Dir(filepath.Dir(binpath))
-			if isGoroot(goroot) {
-				return goroot
-			}
-		}
-	}
-
-	// Check what GOROOT was at compile time.
-	if isGoroot(runtime.GOROOT()) {
-		return runtime.GOROOT()
-	}
-
-	// Check for some standard locations, as a last resort.
-	var candidates []string
-	switch runtime.GOOS {
-	case "linux":
-		candidates = []string{
-			"/usr/local/go",     // manually installed
-			"/usr/lib/go",       // from the distribution
-			"/snap/go/current/", // installed using snap
-		}
-	case "darwin":
-		candidates = []string{
-			"/usr/local/go",             // manually installed
-			"/usr/local/opt/go/libexec", // from Homebrew
-		}
-	}
-
-	for _, candidate := range candidates {
-		if isGoroot(candidate) {
-			return candidate
-		}
-	}
-
-	// Can't find GOROOT...
-	return ""
-}
-
-// isGoroot checks whether the given path looks like a GOROOT.
-func isGoroot(goroot string) bool {
-	_, err := os.Stat(filepath.Join(goroot, "src", "runtime", "internal", "sys", "zversion.go"))
-	return err == nil
-}
-
-// getStandardGoroot returns the physical path to a real, standard Go GOROOT
-// implied by the given path.
-// If the given path appears to be a TinyGo cached GOROOT, it returns the path
-// referenced by symlinks contained in the cache. Otherwise, it returns the
-// given path as-is.
-func getStandardGoroot(path string) string {
-	// Check if the "bin" subdirectory of our given GOROOT is a symlink, and then
-	// return the _parent_ directory of its destination.
-	if dest, err := os.Readlink(filepath.Join(path, "bin")); nil == err {
-		// Clean the destination to remove any trailing slashes, so that
-		// filepath.Dir will always return the parent.
-		//   (because both "/foo" and "/foo/" are valid symlink destinations,
-		//   but filepath.Dir would return "/" and "/foo", respectively)
-		return filepath.Dir(filepath.Clean(dest))
-	}
-	return path
-}

goenv/version.go

@@ -4,15 +4,12 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"os"
-	"path/filepath"
-	"regexp"
 	"strings"
 )
 
 // Version of TinyGo.
 // Update this value before release of new version of software.
-const Version = "0.28.1"
+const Version = "0.29.0"
 
 var (
 	// This variable is set at build time using -ldflags parameters.
@@ -22,8 +19,8 @@ var (
 
 // GetGorootVersion returns the major and minor version for a given GOROOT path.
 // If the goroot cannot be determined, (0, 0) is returned.
-func GetGorootVersion(goroot string) (major, minor int, err error) {
-	s, err := GorootVersionString(goroot)
+func GetGorootVersion() (major, minor int, err error) {
+	s, err := GorootVersionString()
 	if err != nil {
 		return 0, 0, err
 	}
@@ -51,24 +48,9 @@ func GetGorootVersion(goroot string) (major, minor int, err error) {
 }
 
 // GorootVersionString returns the version string as reported by the Go
-// toolchain for the given GOROOT path. It is usually of the form `go1.x.y` but
-// can have some variations (for beta releases, for example).
-func GorootVersionString(goroot string) (string, error) {
-	if data, err := os.ReadFile(filepath.Join(goroot, "VERSION")); err == nil {
-		return string(data), nil
-
-	} else if data, err := os.ReadFile(filepath.Join(
-		goroot, "src", "internal", "buildcfg", "zbootstrap.go")); err == nil {
-
-		r := regexp.MustCompile("const version = `(.*)`")
-		matches := r.FindSubmatch(data)
-		if len(matches) != 2 {
-			return "", errors.New("Invalid go version output:\n" + string(data))
-		}
-
-		return string(matches[1]), nil
-
-	} else {
-		return "", err
-	}
+// toolchain. It is usually of the form `go1.x.y` but can have some variations
+// (for beta releases, for example).
+func GorootVersionString() (string, error) {
+	err := readGoEnvVars()
+	return goEnvVars.GOVERSION, err
 }

loader/goroot.go

@@ -207,6 +207,11 @@ func listGorootMergeLinks(goroot, tinygoroot string, overrides map[string]bool)
 		merges[dir] = filepath.Join(goroot, dir)
 	}
 
+	// Required starting in Go 1.21 due to https://github.com/golang/go/issues/61928
+	if _, err := os.Stat(filepath.Join(goroot, "go.env")); err == nil {
+		merges["go.env"] = filepath.Join(goroot, "go.env")
+	}
+
 	return merges, nil
 }
 

main.go

@@ -19,6 +19,7 @@ import (
 	"regexp"
 	"runtime"
 	"runtime/pprof"
+	"sort"
 	"strconv"
 	"strings"
 	"sync"
@@ -946,112 +947,130 @@ func touchSerialPortAt1200bps(port string) (err error) {
 }
 
 func flashUF2UsingMSD(volumes []string, tmppath string, options *compileopts.Options) error {
-	// find standard UF2 info path
-	infoPaths := make([]string, 0, len(volumes))
-	for _, volume := range volumes {
-		switch runtime.GOOS {
-		case "linux", "freebsd":
-			fi, err := os.Stat("/run/media")
-			if err != nil || !fi.IsDir() {
-				infoPaths = append(infoPaths, "/media/*/"+volume+"/INFO_UF2.TXT")
-			} else {
-				infoPaths = append(infoPaths, "/run/media/*/"+volume+"/INFO_UF2.TXT")
-			}
-		case "darwin":
-			infoPaths = append(infoPaths, "/Volumes/"+volume+"/INFO_UF2.TXT")
-		case "windows":
-			path, err := windowsFindUSBDrive(volume, options)
-			if err == nil {
-				infoPaths = append(infoPaths, path+"/INFO_UF2.TXT")
+	for start := time.Now(); time.Since(start) < options.Timeout; {
+		// Find a UF2 mount point.
+		mounts, err := findFATMounts(options)
+		if err != nil {
+			return err
+		}
+		for _, mount := range mounts {
+			for _, volume := range volumes {
+				if mount.name != volume {
+					continue
+				}
+				if _, err := os.Stat(filepath.Join(mount.path, "INFO_UF2.TXT")); err != nil {
+					// No INFO_UF2.TXT found, which is expected on a UF2
+					// filesystem.
+					continue
+				}
+				// Found the filesystem, so flash the device!
+				return moveFile(tmppath, filepath.Join(mount.path, "flash.uf2"))
 			}
 		}
+		time.Sleep(500 * time.Millisecond)
 	}
-
-	d, err := locateDevice(volumes, infoPaths, options.Timeout)
-	if err != nil {
-		return err
-	}
-
-	return moveFile(tmppath, filepath.Dir(d)+"/flash.uf2")
+	return errors.New("unable to locate any volume: [" + strings.Join(volumes, ",") + "]")
 }
 
 func flashHexUsingMSD(volumes []string, tmppath string, options *compileopts.Options) error {
-	// find expected volume path
-	destPaths := make([]string, 0, len(volumes))
-	for _, volume := range volumes {
-		switch runtime.GOOS {
-		case "linux", "freebsd":
-			fi, err := os.Stat("/run/media")
-			if err != nil || !fi.IsDir() {
-				destPaths = append(destPaths, "/media/*/"+volume)
-			} else {
-				destPaths = append(destPaths, "/run/media/*/"+volume)
-			}
-		case "darwin":
-			destPaths = append(destPaths, "/Volumes/"+volume)
-		case "windows":
-			path, err := windowsFindUSBDrive(volume, options)
-			if err == nil {
-				destPaths = append(destPaths, path+"/")
+	for start := time.Now(); time.Since(start) < options.Timeout; {
+		// Find all mount points.
+		mounts, err := findFATMounts(options)
+		if err != nil {
+			return err
+		}
+		for _, mount := range mounts {
+			for _, volume := range volumes {
+				if mount.name != volume {
+					continue
+				}
+				// Found the filesystem, so flash the device!
+				return moveFile(tmppath, filepath.Join(mount.path, "flash.hex"))
 			}
 		}
-	}
-
-	d, err := locateDevice(volumes, destPaths, options.Timeout)
-	if err != nil {
-		return err
-	}
-
-	return moveFile(tmppath, d+"/flash.hex")
-}
-
-func locateDevice(volumes, paths []string, timeout time.Duration) (string, error) {
-	var d []string
-	var err error
-	for start := time.Now(); time.Since(start) < timeout; {
-		for _, path := range paths {
-			d, err = filepath.Glob(path)
-			if err != nil {
-				return "", err
-			}
-			if d != nil {
-				break
-			}
-		}
-
-		if d != nil {
-			break
-		}
-
 		time.Sleep(500 * time.Millisecond)
 	}
-	if d == nil {
-		return "", errors.New("unable to locate any volume: [" + strings.Join(volumes, ",") + "]")
-	}
-	return d[0], nil
+	return errors.New("unable to locate any volume: [" + strings.Join(volumes, ",") + "]")
 }
 
-func windowsFindUSBDrive(volume string, options *compileopts.Options) (string, error) {
-	cmd := executeCommand(options, "wmic",
-		"PATH", "Win32_LogicalDisk", "WHERE", "VolumeName = '"+volume+"'",
-		"get", "DeviceID,VolumeName,FileSystem,DriveType")
+type mountPoint struct {
+	name string
+	path string
+}
 
-	var out bytes.Buffer
-	cmd.Stdout = &out
-	err := cmd.Run()
-	if err != nil {
-		return "", err
-	}
-
-	for _, line := range strings.Split(out.String(), "\n") {
-		words := strings.Fields(line)
-		if len(words) >= 3 {
-			if words[1] == "2" && words[2] == "FAT" {
-				return words[0], nil
-			}
+// Find all the mount points on the system that use the FAT filesystem.
+func findFATMounts(options *compileopts.Options) ([]mountPoint, error) {
+	var points []mountPoint
+	switch runtime.GOOS {
+	case "darwin":
+		list, err := os.ReadDir("/Volumes")
+		if err != nil {
+			return nil, fmt.Errorf("could not list mount points: %w", err)
 		}
+		for _, elem := range list {
+			// TODO: find a way to check for the filesystem type.
+			// (Only return FAT filesystems).
+			points = append(points, mountPoint{
+				name: elem.Name(),
+				path: filepath.Join("/Volumes", elem.Name()),
+			})
+		}
+		sort.Slice(points, func(i, j int) bool {
+			return points[i].path < points[j].name
+		})
+		return points, nil
+	case "linux":
+		tab, err := os.ReadFile("/proc/mounts") // symlink to /proc/self/mounts on my system
+		if err != nil {
+			return nil, fmt.Errorf("could not list mount points: %w", err)
+		}
+		for _, line := range strings.Split(string(tab), "\n") {
+			fields := strings.Fields(line)
+			if len(fields) <= 2 {
+				continue
+			}
+			fstype := fields[2]
+			if fstype != "vfat" {
+				continue
+			}
+			points = append(points, mountPoint{
+				name: filepath.Base(fields[1]),
+				path: fields[1],
+			})
+		}
+		return points, nil
+	case "windows":
+		// Obtain a list of all currently mounted volumes.
+		cmd := executeCommand(options, "wmic",
+			"PATH", "Win32_LogicalDisk",
+			"get", "DeviceID,VolumeName,FileSystem,DriveType")
+		var out bytes.Buffer
+		cmd.Stdout = &out
+		err := cmd.Run()
+		if err != nil {
+			return nil, fmt.Errorf("could not list mount points: %w", err)
+		}
+
+		// Extract data to convert to a []mountPoint slice.
+		for _, line := range strings.Split(out.String(), "\n") {
+			words := strings.Fields(line)
+			if len(words) < 3 {
+				continue
+			}
+			if words[1] != "2" || words[2] != "FAT" {
+				// - DriveType 2 is removable (which we're looking for).
+				// - We only want to return FAT filesystems.
+				continue
+			}
+			points = append(points, mountPoint{
+				name: words[3],
+				path: words[0],
+			})
+		}
+		return points, nil
+	default:
+		return nil, fmt.Errorf("unknown GOOS for listing mount points: %s", runtime.GOOS)
 	}
-	return "", errors.New("unable to locate a USB device to be flashed")
 }
 
 // getDefaultPort returns the default serial port depending on the operating system.
@@ -1777,15 +1796,17 @@ func main() {
 		}
 		if flagJSON {
 			json, _ := json.MarshalIndent(struct {
-				GOROOT     string   `json:"goroot"`
-				GOOS       string   `json:"goos"`
-				GOARCH     string   `json:"goarch"`
-				GOARM      string   `json:"goarm"`
-				BuildTags  []string `json:"build_tags"`
-				GC         string   `json:"garbage_collector"`
-				Scheduler  string   `json:"scheduler"`
-				LLVMTriple string   `json:"llvm_triple"`
+				Target     *compileopts.TargetSpec `json:"target"`
+				GOROOT     string                  `json:"goroot"`
+				GOOS       string                  `json:"goos"`
+				GOARCH     string                  `json:"goarch"`
+				GOARM      string                  `json:"goarm"`
+				BuildTags  []string                `json:"build_tags"`
+				GC         string                  `json:"garbage_collector"`
+				Scheduler  string                  `json:"scheduler"`
+				LLVMTriple string                  `json:"llvm_triple"`
 			}{
+				Target:     config.Target,
 				GOROOT:     cachedGOROOT,
 				GOOS:       config.GOOS(),
 				GOARCH:     config.GOARCH(),
@@ -1852,7 +1873,7 @@ func main() {
 		usage(command)
 	case "version":
 		goversion := "<unknown>"
-		if s, err := goenv.GorootVersionString(goenv.Get("GOROOT")); err == nil {
+		if s, err := goenv.GorootVersionString(); err == nil {
 			goversion = s
 		}
 		version := goenv.Version

main_test.go

@@ -34,6 +34,16 @@ var supportedLinuxArches = map[string]string{
 	"X86Linux":   "linux/386",
 	"ARMLinux":   "linux/arm/6",
 	"ARM64Linux": "linux/arm64",
+	"WASIp1":     "wasip1/wasm",
+}
+
+func init() {
+	major, _, _ := goenv.GetGorootVersion()
+	if major < 21 {
+		// Go 1.20 backwards compatibility.
+		// Should be removed once we drop support for Go 1.20.
+		delete(supportedLinuxArches, "WASIp1")
+	}
 }
 
 var sema = make(chan struct{}, runtime.NumCPU())
@@ -71,6 +81,16 @@ func TestBuild(t *testing.T) {
 		"zeroalloc.go",
 	}
 
+	// Go 1.21 made some changes to the language, which we can only test when
+	// we're actually on Go 1.21.
+	_, minor, err := goenv.GetGorootVersion()
+	if err != nil {
+		t.Fatal("could not get version:", minor)
+	}
+	if minor >= 21 {
+		tests = append(tests, "go1.21.go")
+	}
+
 	if *testTarget != "" {
 		// This makes it possible to run one specific test (instead of all),
 		// which is especially useful to quickly check whether some changes
@@ -166,6 +186,8 @@ func runPlatTests(options compileopts.Options, tests []string, t *testing.T) {
 		t.Fatal("failed to load target spec:", err)
 	}
 
+	isWebAssembly := options.Target == "wasi" || options.Target == "wasm" || (options.Target == "" && options.GOARCH == "wasm")
+
 	for _, name := range tests {
 		if options.GOOS == "linux" && (options.GOARCH == "arm" || options.GOARCH == "386") {
 			switch name {
@@ -216,7 +238,7 @@ func runPlatTests(options compileopts.Options, tests []string, t *testing.T) {
 			runTest("env.go", options, t, []string{"first", "second"}, []string{"ENV1=VALUE1", "ENV2=VALUE2"})
 		})
 	}
-	if options.Target == "wasi" || options.Target == "wasm" {
+	if isWebAssembly {
 		t.Run("alias.go-scheduler-none", func(t *testing.T) {
 			t.Parallel()
 			options := compileopts.Options(options)
@@ -236,7 +258,7 @@ func runPlatTests(options compileopts.Options, tests []string, t *testing.T) {
 			runTest("rand.go", options, t, nil, nil)
 		})
 	}
-	if options.Target != "wasi" && options.Target != "wasm" {
+	if !isWebAssembly {
 		// The recover() builtin isn't supported yet on WebAssembly and Windows.
 		t.Run("recover.go", func(t *testing.T) {
 			t.Parallel()

src/examples/pininterrupt/arduino.go

@@ -0,0 +1,11 @@
+//go:build arduino
+
+package main
+
+import "machine"
+
+const (
+	button          = machine.D2
+	buttonMode      = machine.PinInputPullup
+	buttonPinChange = machine.PinRising
+)

src/examples/pininterrupt/circuitplay-express.go

@@ -5,6 +5,7 @@ package main
 import "machine"
 
 const (
+	button          = machine.BUTTON
 	buttonMode      = machine.PinInputPulldown
 	buttonPinChange = machine.PinFalling
 )

src/examples/pininterrupt/pca10040.go

@@ -5,6 +5,7 @@ package main
 import "machine"
 
 const (
+	button          = machine.BUTTON
 	buttonMode      = machine.PinInputPullup
 	buttonPinChange = machine.PinRising
 )

src/examples/pininterrupt/pininterrupt.go

@@ -8,18 +8,14 @@ package main
 
 import (
 	"machine"
-	"runtime/volatile"
 	"time"
 )
 
 const (
-	button = machine.BUTTON
-	led    = machine.LED
+	led = machine.LED
 )
 
 func main() {
-	var lightLed volatile.Register8
-	lightLed.Set(0)
 
 	// Configure the LED, defaulting to on (usually setting the pin to low will
 	// turn the LED on).
@@ -33,13 +29,7 @@ func main() {
 
 	// Set an interrupt on this pin.
 	err := button.SetInterrupt(buttonPinChange, func(machine.Pin) {
-		if lightLed.Get() != 0 {
-			lightLed.Set(0)
-			led.Low()
-		} else {
-			lightLed.Set(1)
-			led.High()
-		}
+		led.Set(!led.Get())
 	})
 	if err != nil {
 		println("could not configure pin interrupt:", err.Error())

src/examples/pininterrupt/stm32.go

@@ -5,6 +5,7 @@ package main
 import "machine"
 
 const (
+	button          = machine.BUTTON
 	buttonMode      = machine.PinInputPulldown
 	buttonPinChange = machine.PinRising | machine.PinFalling
 )

src/examples/pininterrupt/wioterminal.go

@@ -5,6 +5,7 @@ package main
 import "machine"
 
 const (
+	button          = machine.BUTTON
 	buttonMode      = machine.PinInput
 	buttonPinChange = machine.PinFalling
 )

src/examples/time-offset/time-offset.go

@@ -0,0 +1,32 @@
+package main
+
+// This example demonstrates how to set the system time.
+//
+// Usually, boards don't keep time on power cycles and restarts, it resets to Unix epoch.
+// The system time can be set by calling runtime.AdjustTimeOffset().
+//
+// Possible time sources: an external RTC clock or network (WiFi access point or NTP server)
+
+import (
+	"fmt"
+	"runtime"
+	"time"
+)
+
+const myTime = "2006-01-02T15:04:05Z" // this is an example time you source somewhere
+
+func main() {
+
+	// measure how many nanoseconds the internal clock is behind
+	timeOfMeasurement := time.Now()
+	actualTime, _ := time.Parse(time.RFC3339, myTime)
+	offset := actualTime.Sub(timeOfMeasurement)
+
+	// adjust internal clock by adding the offset to the internal clock
+	runtime.AdjustTimeOffset(int64(offset))
+
+	for {
+		fmt.Printf("%v\r\n", time.Now().Format(time.RFC3339))
+		time.Sleep(5 * time.Second)
+	}
+}

src/examples/watchdog/main.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"fmt"
+	"machine"
+	"time"
+)
+
+func main() {
+	//sleep for 2 secs for console
+	time.Sleep(2 * time.Second)
+
+	config := machine.WatchdogConfig{
+		TimeoutMillis: 1000,
+	}
+
+	println("configuring watchdog for max 1 second updates")
+	machine.Watchdog.Configure(config)
+
+	// From this point the watchdog is running and Update must be
+	// called periodically, per the config
+	machine.Watchdog.Start()
+
+	// This loop should complete because watchdog update is called
+	// every 100ms.
+	start := time.Now()
+	println("updating watchdog for 3 seconds")
+	for i := 0; i < 30; i++ {
+		time.Sleep(100 * time.Millisecond)
+		machine.Watchdog.Update()
+		fmt.Printf("alive @ %v\n", time.Now().Sub(start))
+	}
+
+	// This loop should cause a watchdog reset after 1s since
+	// there is no update call.
+	start = time.Now()
+	println("entering tight loop")
+	for {
+		time.Sleep(100 * time.Millisecond)
+		fmt.Printf("alive @ %v\n", time.Now().Sub(start))
+	}
+}

src/internal/bytealg/bytealg.go

@@ -251,3 +251,13 @@ func IndexRabinKarp(s, substr string) int {
 	}
 	return -1
 }
+
+// MakeNoZero makes a slice of length and capacity n without zeroing the bytes.
+// It is the caller's responsibility to ensure uninitialized bytes
+// do not leak to the end user.
+func MakeNoZero(n int) []byte {
+	// Note: this does zero the buffer even though that's not necessary.
+	// For performance reasons we might want to change this (similar to the
+	// malloc function implemented in the runtime).
+	return make([]byte, n)
+}

src/machine/board_ae_rp2040.go

@@ -0,0 +1,111 @@
+//go:build ae_rp2040
+
+package machine
+
+import (
+	"device/rp"
+	"runtime/interrupt"
+)
+
+// GPIO pins
+const (
+	GP0  Pin = GPIO0
+	GP1  Pin = GPIO1
+	GP2  Pin = GPIO2
+	GP3  Pin = GPIO3
+	GP4  Pin = GPIO4
+	GP5  Pin = GPIO5
+	GP6  Pin = GPIO6
+	GP7  Pin = GPIO7
+	GP8  Pin = GPIO8
+	GP9  Pin = GPIO9
+	GP10 Pin = GPIO10
+	GP11 Pin = GPIO11
+	GP12 Pin = GPIO12
+	GP13 Pin = GPIO13
+	GP14 Pin = GPIO14
+	GP15 Pin = GPIO15
+	GP16 Pin = GPIO16
+	GP17 Pin = GPIO17
+	GP18 Pin = GPIO18
+	GP19 Pin = GPIO19
+	GP20 Pin = GPIO20
+	GP21 Pin = GPIO21
+	GP22 Pin = GPIO22
+	GP26 Pin = GPIO26
+	GP27 Pin = GPIO27
+	GP28 Pin = GPIO28
+	GP29 Pin = GPIO29
+
+	// Onboard crystal oscillator frequency, in MHz.
+	xoscFreq = 12 // MHz
+)
+
+// I2C Default pins on Raspberry Pico.
+const (
+	I2C0_SDA_PIN = GP4
+	I2C0_SCL_PIN = GP5
+
+	I2C1_SDA_PIN = GP2
+	I2C1_SCL_PIN = GP3
+)
+
+// SPI default pins
+const (
+	// Default Serial Clock Bus 0 for SPI communications
+	SPI0_SCK_PIN = GPIO18
+	// Default Serial Out Bus 0 for SPI communications
+	SPI0_SDO_PIN = GPIO19 // Tx
+	// Default Serial In Bus 0 for SPI communications
+	SPI0_SDI_PIN = GPIO16 // Rx
+
+	// Default Serial Clock Bus 1 for SPI communications
+	SPI1_SCK_PIN = GPIO10
+	// Default Serial Out Bus 1 for SPI communications
+	SPI1_SDO_PIN = GPIO11 // Tx
+	// Default Serial In Bus 1 for SPI communications
+	SPI1_SDI_PIN = GPIO12 // Rx
+)
+
+// UART pins
+const (
+	UART0_TX_PIN = GPIO0
+	UART0_RX_PIN = GPIO1
+	UART1_TX_PIN = GPIO8
+	UART1_RX_PIN = GPIO9
+	UART_TX_PIN  = UART0_TX_PIN
+	UART_RX_PIN  = UART0_RX_PIN
+)
+
+// UART on the RP2040
+var (
+	UART0  = &_UART0
+	_UART0 = UART{
+		Buffer: NewRingBuffer(),
+		Bus:    rp.UART0,
+	}
+
+	UART1  = &_UART1
+	_UART1 = UART{
+		Buffer: NewRingBuffer(),
+		Bus:    rp.UART1,
+	}
+)
+
+var DefaultUART = UART0
+
+func init() {
+	UART0.Interrupt = interrupt.New(rp.IRQ_UART0_IRQ, _UART0.handleInterrupt)
+	UART1.Interrupt = interrupt.New(rp.IRQ_UART1_IRQ, _UART1.handleInterrupt)
+}
+
+// USB identifiers
+const (
+	usb_STRING_PRODUCT      = "AE-RP2040"
+	usb_STRING_MANUFACTURER = "AKIZUKI DENSHI"
+)
+
+var (
+	usb_VID uint16 = 0x2E8A
+	usb_PID uint16 = 0x000A
+)

src/machine/board_macropad-rp2040.go

@@ -16,6 +16,7 @@ const (
 
 const (
 	SWITCH = GPIO0
+	BUTTON = GPIO0
 
 	KEY1  = GPIO1
 	KEY2  = GPIO2

src/machine/machine_atmega.go

@@ -97,7 +97,7 @@ func (i2c *I2C) stop() {
 }
 
 // writeByte writes a single byte to the I2C bus.
-func (i2c *I2C) writeByte(data byte) {
+func (i2c *I2C) writeByte(data byte) error {
 	// Write data to register.
 	avr.TWDR.Set(data)
 
@@ -107,6 +107,7 @@ func (i2c *I2C) writeByte(data byte) {
 	// Wait till data is transmitted.
 	for !avr.TWCR.HasBits(avr.TWCR_TWINT) {
 	}
+	return nil
 }
 
 // readByte reads a single byte from the I2C bus.
@@ -190,7 +191,7 @@ func (uart *UART) handleInterrupt(intr interrupt.Interrupt) {
 }
 
 // WriteByte writes a byte of data to the UART.
-func (uart *UART) WriteByte(c byte) error {
+func (uart *UART) writeByte(c byte) error {
 	// Wait until UART buffer is not busy.
 	for !uart.statusRegA.HasBits(avr.UCSR0A_UDRE0) {
 	}
@@ -198,6 +199,8 @@ func (uart *UART) WriteByte(c byte) error {
 	return nil
 }
 
+func (uart *UART) flush() {}
+
 // SPIConfig is used to store config info for SPI.
 type SPIConfig struct {
 	Frequency uint32

src/machine/machine_atmega328p.go

@@ -466,3 +466,107 @@ var SPI0 = SPI{
 	sdo:  PB3,
 	sdi:  PB4,
 	cs:   PB2}
+
+// Pin Change Interrupts
+type PinChange uint8
+
+const (
+	PinRising PinChange = 1 << iota
+	PinFalling
+	PinToggle = PinRising | PinFalling
+)
+
+func (pin Pin) SetInterrupt(pinChange PinChange, callback func(Pin)) (err error) {
+
+	switch {
+	case pin >= PB0 && pin <= PB7:
+		// PCMSK0 - PCINT0-7
+		pinStates[0] = avr.PINB.Get()
+		pinIndex := pin - PB0
+		if pinChange&PinRising > 0 {
+			pinCallbacks[0][pinIndex][0] = callback
+		}
+		if pinChange&PinFalling > 0 {
+			pinCallbacks[0][pinIndex][1] = callback
+		}
+		if callback != nil {
+			avr.PCMSK0.SetBits(1 << pinIndex)
+		} else {
+			avr.PCMSK0.ClearBits(1 << pinIndex)
+		}
+		avr.PCICR.SetBits(avr.PCICR_PCIE0)
+		interrupt.New(avr.IRQ_PCINT0, handlePCINT0Interrupts)
+	case pin >= PC0 && pin <= PC7:
+		// PCMSK1 - PCINT8-14
+		pinStates[1] = avr.PINC.Get()
+		pinIndex := pin - PC0
+		if pinChange&PinRising > 0 {
+			pinCallbacks[1][pinIndex][0] = callback
+		}
+		if pinChange&PinFalling > 0 {
+			pinCallbacks[1][pinIndex][1] = callback
+		}
+		if callback != nil {
+			avr.PCMSK1.SetBits(1 << pinIndex)
+		} else {
+			avr.PCMSK1.ClearBits(1 << pinIndex)
+		}
+		avr.PCICR.SetBits(avr.PCICR_PCIE1)
+		interrupt.New(avr.IRQ_PCINT1, handlePCINT1Interrupts)
+	case pin >= PD0 && pin <= PD7:
+		// PCMSK2 - PCINT16-23
+		pinStates[2] = avr.PIND.Get()
+		pinIndex := pin - PD0
+		if pinChange&PinRising > 0 {
+			pinCallbacks[2][pinIndex][0] = callback
+		}
+		if pinChange&PinFalling > 0 {
+			pinCallbacks[2][pinIndex][1] = callback
+		}
+		if callback != nil {
+			avr.PCMSK2.SetBits(1 << pinIndex)
+		} else {
+			avr.PCMSK2.ClearBits(1 << pinIndex)
+		}
+		avr.PCICR.SetBits(avr.PCICR_PCIE2)
+		interrupt.New(avr.IRQ_PCINT2, handlePCINT2Interrupts)
+	default:
+		return ErrInvalidInputPin
+	}
+
+	return nil
+}
+
+var pinCallbacks [3][8][2]func(Pin)
+var pinStates [3]uint8
+
+func handlePCINTInterrupts(intr uint8, port *volatile.Register8) {
+	current := port.Get()
+	change := pinStates[intr] ^ current
+	pinStates[intr] = current
+	for i := uint8(0); i < 8; i++ {
+		if (change>>i)&0x01 != 0x01 {
+			continue
+		}
+		pin := Pin(intr*8 + i)
+		value := pin.Get()
+		if value && pinCallbacks[intr][i][0] != nil {
+			pinCallbacks[intr][i][0](pin)
+		}
+		if !value && pinCallbacks[intr][i][1] != nil {
+			pinCallbacks[intr][i][1](pin)
+		}
+	}
+}
+
+func handlePCINT0Interrupts(intr interrupt.Interrupt) {
+	handlePCINTInterrupts(0, avr.PINB)
+}
+
+func handlePCINT1Interrupts(intr interrupt.Interrupt) {
+	handlePCINTInterrupts(1, avr.PINC)
+}
+
+func handlePCINT2Interrupts(intr interrupt.Interrupt) {
+	handlePCINTInterrupts(2, avr.PIND)
+}

src/machine/machine_atsamd21.go

@@ -626,7 +626,7 @@ func (uart *UART) SetBaudRate(br uint32) {
 }
 
 // WriteByte writes a byte of data to the UART.
-func (uart *UART) WriteByte(c byte) error {
+func (uart *UART) writeByte(c byte) error {
 	// wait until ready to receive
 	for !uart.Bus.INTFLAG.HasBits(sam.SERCOM_USART_INTFLAG_DRE) {
 	}
@@ -634,6 +634,8 @@ func (uart *UART) WriteByte(c byte) error {
 	return nil
 }
 
+func (uart *UART) flush() {}
+
 // handleInterrupt should be called from the appropriate interrupt handler for
 // this UART instance.
 func (uart *UART) handleInterrupt(interrupt.Interrupt) {

src/machine/machine_atsamd51.go

@@ -1114,7 +1114,7 @@ func (uart *UART) SetBaudRate(br uint32) {
 }
 
 // WriteByte writes a byte of data to the UART.
-func (uart *UART) WriteByte(c byte) error {
+func (uart *UART) writeByte(c byte) error {
 	// wait until ready to receive
 	for !uart.Bus.INTFLAG.HasBits(sam.SERCOM_USART_INT_INTFLAG_DRE) {
 	}
@@ -1122,6 +1122,8 @@ func (uart *UART) WriteByte(c byte) error {
 	return nil
 }
 
+func (uart *UART) flush() {}
+
 func (uart *UART) handleInterrupt(interrupt.Interrupt) {
 	// should reset IRQ
 	uart.Receive(byte((uart.Bus.DATA.Get() & 0xFF)))
@@ -1162,7 +1164,7 @@ const (
 	wireCmdStop        = 3
 )
 
-const i2cTimeout = 1000
+const i2cTimeout = 28000 // about 210us
 
 // Configure is intended to setup the I2C interface.
 func (i2c *I2C) Configure(config I2CConfig) error {
@@ -2297,3 +2299,52 @@ func checkFlashError() error {
 
 	return nil
 }
+
+// Watchdog provides access to the hardware watchdog available
+// in the SAMD51.
+var Watchdog = &watchdogImpl{}
+
+const (
+	// WatchdogMaxTimeout in milliseconds (16s)
+	WatchdogMaxTimeout = (16384 * 1000) / 1024 // CYC16384/1024kHz
+)
+
+type watchdogImpl struct{}
+
+// Configure the watchdog.
+//
+// This method should not be called after the watchdog is started and on
+// some platforms attempting to reconfigure after starting the watchdog
+// is explicitly forbidden / will not work.
+func (wd *watchdogImpl) Configure(config WatchdogConfig) error {
+	// 1.024kHz clock
+	cycles := int((int64(config.TimeoutMillis) * 1024) / 1000)
+
+	// period is expressed as a power-of-two, starting at 8 / 1024ths of a second
+	period := uint8(0)
+	cfgCycles := 8
+	for cfgCycles < cycles {
+		period++
+		cfgCycles <<= 1
+
+		if period >= 0xB {
+			break
+		}
+	}
+
+	sam.WDT.CONFIG.Set(period << sam.WDT_CONFIG_PER_Pos)
+
+	return nil
+}
+
+// Starts the watchdog.
+func (wd *watchdogImpl) Start() error {
+	sam.WDT.CTRLA.SetBits(sam.WDT_CTRLA_ENABLE)
+	return nil
+}
+
+// Update the watchdog, indicating that `source` is healthy.
+func (wd *watchdogImpl) Update() {
+	// 0xA5 = magic value (see datasheet)
+	sam.WDT.CLEAR.Set(0xA5)
+}

src/machine/machine_esp32.go

@@ -314,7 +314,7 @@ func (uart *UART) Configure(config UARTConfig) {
 	uart.Bus.CLKDIV.Set(peripheralClock / config.BaudRate)
 }
 
-func (uart *UART) WriteByte(b byte) error {
+func (uart *UART) writeByte(b byte) error {
 	for (uart.Bus.STATUS.Get()>>16)&0xff >= 128 {
 		// Read UART_TXFIFO_CNT from the status register, which indicates how
 		// many bytes there are in the transmit buffer. Wait until there are
@@ -324,6 +324,8 @@ func (uart *UART) WriteByte(b byte) error {
 	return nil
 }
 
+func (uart *UART) flush() {}
+
 // Serial Peripheral Interface on the ESP32.
 type SPI struct {
 	Bus *esp.SPI_Type

src/machine/machine_esp32c3.go

@@ -493,7 +493,7 @@ func (uart *UART) enableReceiver() {
 	uart.Bus.SetINT_ENA_RXFIFO_OVF_INT_ENA(1)
 }
 
-func (uart *UART) WriteByte(b byte) error {
+func (uart *UART) writeByte(b byte) error {
 	for (uart.Bus.STATUS.Get()&esp.UART_STATUS_TXFIFO_CNT_Msk)>>esp.UART_STATUS_TXFIFO_CNT_Pos >= 128 {
 		// Read UART_TXFIFO_CNT from the status register, which indicates how
 		// many bytes there are in the transmit buffer. Wait until there are
@@ -502,3 +502,5 @@ func (uart *UART) WriteByte(b byte) error {
 	uart.Bus.FIFO.Set(uint32(b))
 	return nil
 }
+
+func (uart *UART) flush() {}

src/machine/machine_esp8266.go

@@ -181,12 +181,14 @@ func (uart *UART) Configure(config UARTConfig) {
 	esp.UART0.UART_CLKDIV.Set(CPUFrequency() / config.BaudRate)
 }
 
-// WriteByte writes a single byte to the output buffer. Note that the hardware
+// writeByte writes a single byte to the output buffer. Note that the hardware
 // includes a buffer of 128 bytes which will be used first.
-func (uart *UART) WriteByte(c byte) error {
+func (uart *UART) writeByte(c byte) error {
 	for (esp.UART0.UART_STATUS.Get()>>16)&0xff >= 128 {
 		// Wait until the TX buffer has room.
 	}
 	esp.UART0.UART_FIFO.Set(uint32(c))
 	return nil
 }
+
+func (uart *UART) flush() {}

src/machine/machine_fe310.go

@@ -111,13 +111,16 @@ func (uart *UART) handleInterrupt(interrupt.Interrupt) {
 	uart.Receive(c)
 }
 
-func (uart *UART) WriteByte(c byte) {
+func (uart *UART) writeByte(c byte) error {
 	for sifive.UART0.TXDATA.Get()&sifive.UART_TXDATA_FULL != 0 {
 	}
 
 	sifive.UART0.TXDATA.Set(uint32(c))
+	return nil
 }
 
+func (uart *UART) flush() {}
+
 // SPI on the FE310. The normal SPI0 is actually a quad-SPI meant for flash, so it is best
 // to use SPI1 or SPI2 port for most applications.
 type SPI struct {

src/machine/machine_k210.go

@@ -392,13 +392,16 @@ func (uart *UART) handleInterrupt(interrupt.Interrupt) {
 	uart.Receive(c)
 }
 
-func (uart *UART) WriteByte(c byte) {
+func (uart *UART) writeByte(c byte) error {
 	for uart.Bus.TXDATA.Get()&kendryte.UARTHS_TXDATA_FULL != 0 {
 	}
 
 	uart.Bus.TXDATA.Set(uint32(c))
+	return nil
 }
 
+func (uart *UART) flush() {}
+
 type SPI struct {
 	Bus *kendryte.SPI_Type
 }

src/machine/machine_mimxrt1062_uart.go

@@ -173,7 +173,7 @@ func (uart *UART) Sync() error {
 }
 
 // WriteByte writes a single byte of data to the UART interface.
-func (uart *UART) WriteByte(c byte) error {
+func (uart *UART) writeByte(c byte) error {
 	uart.startTransmitting()
 	for !uart.txBuffer.Put(c) {
 	}
@@ -181,6 +181,8 @@ func (uart *UART) WriteByte(c byte) error {
 	return nil
 }
 
+func (uart *UART) flush() {}
+
 // getBaudRateDivisor finds the greatest over-sampling factor (4..32) and
 // corresponding baud rate divisor (1..8191) that best partition a given baud
 // rate into equal intervals.

src/machine/machine_nrf.go

@@ -186,7 +186,7 @@ func (uart *UART) SetBaudRate(br uint32) {
 }
 
 // WriteByte writes a byte of data to the UART.
-func (uart *UART) WriteByte(c byte) error {
+func (uart *UART) writeByte(c byte) error {
 	nrf.UART0.EVENTS_TXDRDY.Set(0)
 	nrf.UART0.TXD.Set(uint32(c))
 	for nrf.UART0.EVENTS_TXDRDY.Get() == 0 {
@@ -194,6 +194,8 @@ func (uart *UART) WriteByte(c byte) error {
 	return nil
 }
 
+func (uart *UART) flush() {}
+
 func (uart *UART) handleInterrupt(interrupt.Interrupt) {
 	if nrf.UART0.EVENTS_RXDRDY.Get() != 0 {
 		uart.Receive(byte(nrf.UART0.RXD.Get()))
@@ -201,6 +203,8 @@ func (uart *UART) handleInterrupt(interrupt.Interrupt) {
 	}
 }
 
+const i2cTimeout = 0xffff // this is around 29ms on a nrf52
+
 // I2CConfig is used to store config info for I2C.
 type I2CConfig struct {
 	Frequency uint32
@@ -259,11 +263,17 @@ func (i2c *I2C) Configure(config I2CConfig) error {
 }
 
 // signalStop sends a stop signal to the I2C peripheral and waits for confirmation.
-func (i2c *I2C) signalStop() {
+func (i2c *I2C) signalStop() error {
+	tries := 0
 	i2c.Bus.TASKS_STOP.Set(1)
 	for i2c.Bus.EVENTS_STOPPED.Get() == 0 {
+		tries++
+		if tries >= i2cTimeout {
+			return errI2CSignalStopTimeout
+		}
 	}
 	i2c.Bus.EVENTS_STOPPED.Set(0)
+	return nil
 }
 
 var rngStarted = false

src/machine/machine_nrf528xx.go

@@ -214,3 +214,46 @@ func twisError(val uint32) error {
 
 	return errI2CBusError
 }
+
+var (
+	Watchdog = &watchdogImpl{}
+)
+
+const (
+	// WatchdogMaxTimeout in milliseconds (approx 36h)
+	WatchdogMaxTimeout = (0xffffffff * 1000) / 32768
+)
+
+type watchdogImpl struct {
+}
+
+// Configure the watchdog.
+//
+// This method should not be called after the watchdog is started and on
+// some platforms attempting to reconfigure after starting the watchdog
+// is explicitly forbidden / will not work.
+func (wd *watchdogImpl) Configure(config WatchdogConfig) error {
+	// 32.768kHz counter
+	crv := int32((int64(config.TimeoutMillis) * 32768) / 1000)
+	nrf.WDT.CRV.Set(uint32(crv))
+
+	// One source
+	nrf.WDT.RREN.Set(0x1)
+
+	// Run during sleep
+	nrf.WDT.CONFIG.Set(nrf.WDT_CONFIG_SLEEP_Run)
+
+	return nil
+}
+
+// Starts the watchdog.
+func (wd *watchdogImpl) Start() error {
+	nrf.WDT.TASKS_START.Set(nrf.WDT_TASKS_START_TASKS_START)
+	return nil
+}
+
+// Update the watchdog, indicating that `source` is healthy.
+func (wd *watchdogImpl) Update() {
+	// 0x6E524635 = magic value from datasheet
+	nrf.WDT.RR[0].Set(0x6E524635)
+}

src/machine/machine_nrf52xxx.go

@@ -288,24 +288,27 @@ func (spi SPI) Tx(w, r []byte) error {
 	// supported.
 	for len(r) != 0 || len(w) != 0 {
 		// Prepare the SPI transfer: set the DMA pointers and lengths.
-		if len(r) != 0 {
+		// read buffer
+		nr := uint32(len(r))
+		if nr > 0 {
+			if nr > 255 {
+				nr = 255
+			}
 			spi.Bus.RXD.PTR.Set(uint32(uintptr(unsafe.Pointer(&r[0]))))
-			n := uint32(len(r))
-			if n > 255 {
-				n = 255
-			}
-			spi.Bus.RXD.MAXCNT.Set(n)
-			r = r[n:]
+			r = r[nr:]
 		}
-		if len(w) != 0 {
+		spi.Bus.RXD.MAXCNT.Set(nr)
+
+		// write buffer
+		nw := uint32(len(w))
+		if nw > 0 {
+			if nw > 255 {
+				nw = 255
+			}
 			spi.Bus.TXD.PTR.Set(uint32(uintptr(unsafe.Pointer(&w[0]))))
-			n := uint32(len(w))
-			if n > 255 {
-				n = 255
-			}
-			spi.Bus.TXD.MAXCNT.Set(n)
-			w = w[n:]
+			w = w[nw:]
 		}
+		spi.Bus.TXD.MAXCNT.Set(nw)
 
 		// Do the transfer.
 		// Note: this can be improved by not waiting until the transfer is

src/machine/machine_nrf5x.go

@@ -70,11 +70,21 @@ func (i2c *I2C) Tx(addr uint16, w, r []byte) (err error) {
 		i2c.Bus.SHORTS.Set(nrf.TWI_SHORTS_BB_SUSPEND_Disabled)
 	}
 
-	// Stop explicitly when no reads were executed, stoping unconditionally would be a mistake.
-	// It may execute after I2C peripheral has already been stopped by the shortcut in the read block,
-	// so stop task will trigger first thing in a subsequent transaction, hanging it.
 	if len(r) == 0 {
-		i2c.signalStop()
+		// Stop the I2C transaction after the write.
+		err = i2c.signalStop()
+	} else {
+		// The last byte read has already stopped the transaction, via
+		// TWI_SHORTS_BB_STOP. But we still need to wait until we receive the
+		// STOPPED event.
+		tries := 0
+		for i2c.Bus.EVENTS_STOPPED.Get() == 0 {
+			tries++
+			if tries >= i2cTimeout {
+				return errI2CSignalStopTimeout
+			}
+		}
+		i2c.Bus.EVENTS_STOPPED.Set(0)
 	}
 
 	return
@@ -82,12 +92,17 @@ func (i2c *I2C) Tx(addr uint16, w, r []byte) (err error) {
 
 // writeByte writes a single byte to the I2C bus and waits for confirmation.
 func (i2c *I2C) writeByte(data byte) error {
+	tries := 0
 	i2c.Bus.TXD.Set(uint32(data))
 	for i2c.Bus.EVENTS_TXDSENT.Get() == 0 {
 		if e := i2c.Bus.EVENTS_ERROR.Get(); e != 0 {
 			i2c.Bus.EVENTS_ERROR.Set(0)
 			return errI2CBusError
 		}
+		tries++
+		if tries >= i2cTimeout {
+			return errI2CWriteTimeout
+		}
 	}
 	i2c.Bus.EVENTS_TXDSENT.Set(0)
 	return nil
@@ -95,11 +110,16 @@ func (i2c *I2C) writeByte(data byte) error {
 
 // readByte reads a single byte from the I2C bus when it is ready.
 func (i2c *I2C) readByte() (byte, error) {
+	tries := 0
 	for i2c.Bus.EVENTS_RXDREADY.Get() == 0 {
 		if e := i2c.Bus.EVENTS_ERROR.Get(); e != 0 {
 			i2c.Bus.EVENTS_ERROR.Set(0)
 			return 0, errI2CBusError
 		}
+		tries++
+		if tries >= i2cTimeout {
+			return 0, errI2CReadTimeout
+		}
 	}
 	i2c.Bus.EVENTS_RXDREADY.Set(0)
 	return byte(i2c.Bus.RXD.Get()), nil

src/machine/machine_nxpmk66f18_uart.go

@@ -292,7 +292,7 @@ func (u *UART) handleStatusInterrupt(interrupt.Interrupt) {
 }
 
 // WriteByte writes a byte of data to the UART.
-func (u *UART) WriteByte(c byte) error {
+func (u *UART) writeByte(c byte) error {
 	if !u.Configured {
 		return ErrNotConfigured
 	}
@@ -305,3 +305,5 @@ func (u *UART) WriteByte(c byte) error {
 	u.C2.Set(uartC2TXActive)
 	return nil
 }
+
+func (uart *UART) flush() {}

src/machine/machine_rp2040_clocks.go

@@ -182,7 +182,7 @@ func (clk *clock) configure(src, auxsrc, srcFreq, freq uint32) {
 // Must be called before any other clock function.
 func (clks *clocksType) init() {
 	// Start the watchdog tick
-	watchdog.startTick(xoscFreq)
+	Watchdog.startTick(xoscFreq)
 
 	// Disable resus that may be enabled from previous software
 	clks.resus.ctrl.Set(0)

src/machine/machine_rp2040_flash.go

@@ -0,0 +1,97 @@
+//go:build rp2040
+
+package machine
+
+import (
+	"bytes"
+	"unsafe"
+)
+
+// EnterBootloader should perform a system reset in preparation
+// to switch to the bootloader to flash new firmware.
+func EnterBootloader() {
+	enterBootloader()
+}
+
+// compile-time check for ensuring we fulfill BlockDevice interface
+var _ BlockDevice = flashBlockDevice{}
+
+var Flash flashBlockDevice
+
+type flashBlockDevice struct {
+}
+
+// ReadAt reads the given number of bytes from the block device.
+func (f flashBlockDevice) ReadAt(p []byte, off int64) (n int, err error) {
+	if readAddress(off) > FlashDataEnd() {
+		return 0, errFlashCannotReadPastEOF
+	}
+
+	data := unsafe.Slice((*byte)(unsafe.Pointer(readAddress(off))), len(p))
+	copy(p, data)
+
+	return len(p), nil
+}
+
+// WriteAt writes the given number of bytes to the block device.
+// Only word (32 bits) length data can be programmed.
+// If the length of p is not long enough it will be padded with 0xFF bytes.
+// This method assumes that the destination is already erased.
+func (f flashBlockDevice) WriteAt(p []byte, off int64) (n int, err error) {
+	return f.writeAt(p, off)
+}
+
+// Size returns the number of bytes in this block device.
+func (f flashBlockDevice) Size() int64 {
+	return int64(FlashDataEnd() - FlashDataStart())
+}
+
+const writeBlockSize = 1 << 8
+
+// WriteBlockSize returns the block size in which data can be written to
+// memory. It can be used by a client to optimize writes, non-aligned writes
+// should always work correctly.
+func (f flashBlockDevice) WriteBlockSize() int64 {
+	return writeBlockSize
+}
+
+const eraseBlockSizeValue = 1 << 12
+
+func eraseBlockSize() int64 {
+	return eraseBlockSizeValue
+}
+
+// EraseBlockSize returns the smallest erasable area on this particular chip
+// in bytes. This is used for the block size in EraseBlocks.
+func (f flashBlockDevice) EraseBlockSize() int64 {
+	return eraseBlockSize()
+}
+
+// EraseBlocks erases the given number of blocks. An implementation may
+// transparently coalesce ranges of blocks into larger bundles if the chip
+// supports this. The start and len parameters are in block numbers, use
+// EraseBlockSize to map addresses to blocks.
+func (f flashBlockDevice) EraseBlocks(start, length int64) error {
+	return f.eraseBlocks(start, length)
+}
+
+// pad data if needed so it is long enough for correct byte alignment on writes.
+func (f flashBlockDevice) pad(p []byte) []byte {
+	overflow := int64(len(p)) % f.WriteBlockSize()
+	if overflow == 0 {
+		return p
+	}
+
+	padding := bytes.Repeat([]byte{0xff}, int(f.WriteBlockSize()-overflow))
+	return append(p, padding...)
+}
+
+// return the correct address to be used for write
+func writeAddress(off int64) uintptr {
+	return readAddress(off) - uintptr(memoryStart)
+}
+
+// return the correct address to be used for reads
+func readAddress(off int64) uintptr {
+	return FlashDataStart() + uintptr(off)
+}

src/machine/machine_rp2040_gpio.go

@@ -174,6 +174,9 @@ func (p Pin) init() {
 
 // Configure configures the gpio pin as per mode.
 func (p Pin) Configure(config PinConfig) {
+	if p == NoPin {
+		return
+	}
 	p.init()
 	mask := uint32(1) << p
 	switch config.Mode {
@@ -213,6 +216,9 @@ func (p Pin) Configure(config PinConfig) {
 
 // Set drives the pin high if value is true else drives it low.
 func (p Pin) Set(value bool) {
+	if p == NoPin {
+		return
+	}
 	if value {
 		p.set()
 	} else {
@@ -251,6 +257,9 @@ var (
 // nil func to unset the pin change interrupt. If you do so, the change
 // parameter is ignored and can be set to any value (such as 0).
 func (p Pin) SetInterrupt(change PinChange, callback func(Pin)) error {
+	if p == NoPin {
+		return nil
+	}
 	if p > 31 || p < 0 {
 		return ErrInvalidInputPin
 	}

src/machine/machine_rp2040_rom.go

@@ -3,7 +3,6 @@
 package machine
 
 import (
-	"bytes"
 	"runtime/interrupt"
 	"unsafe"
 )
@@ -136,40 +135,14 @@ void ram_func flash_erase_blocks(uint32_t offset, size_t count)
 */
 import "C"
 
-// EnterBootloader should perform a system reset in preparation
-// to switch to the bootloader to flash new firmware.
-func EnterBootloader() {
+func enterBootloader() {
 	C.reset_usb_boot(0, 0)
 }
 
 // Flash related code
 const memoryStart = C.XIP_BASE // memory start for purpose of erase
 
-// compile-time check for ensuring we fulfill BlockDevice interface
-var _ BlockDevice = flashBlockDevice{}
-
-var Flash flashBlockDevice
-
-type flashBlockDevice struct {
-}
-
-// ReadAt reads the given number of bytes from the block device.
-func (f flashBlockDevice) ReadAt(p []byte, off int64) (n int, err error) {
-	if readAddress(off) > FlashDataEnd() {
-		return 0, errFlashCannotReadPastEOF
-	}
-
-	data := unsafe.Slice((*byte)(unsafe.Pointer(readAddress(off))), len(p))
-	copy(p, data)
-
-	return len(p), nil
-}
-
-// WriteAt writes the given number of bytes to the block device.
-// Only word (32 bits) length data can be programmed.
-// If the length of p is not long enough it will be padded with 0xFF bytes.
-// This method assumes that the destination is already erased.
-func (f flashBlockDevice) WriteAt(p []byte, off int64) (n int, err error) {
+func (f flashBlockDevice) writeAt(p []byte, off int64) (n int, err error) {
 	if writeAddress(off)+uintptr(C.XIP_BASE) > FlashDataEnd() {
 		return 0, errFlashCannotWritePastEOF
 	}
@@ -190,37 +163,7 @@ func (f flashBlockDevice) WriteAt(p []byte, off int64) (n int, err error) {
 	return len(padded), nil
 }
 
-// Size returns the number of bytes in this block device.
-func (f flashBlockDevice) Size() int64 {
-	return int64(FlashDataEnd() - FlashDataStart())
-}
-
-const writeBlockSize = 1 << 8
-
-// WriteBlockSize returns the block size in which data can be written to
-// memory. It can be used by a client to optimize writes, non-aligned writes
-// should always work correctly.
-func (f flashBlockDevice) WriteBlockSize() int64 {
-	return writeBlockSize
-}
-
-const eraseBlockSizeValue = 1 << 12
-
-func eraseBlockSize() int64 {
-	return eraseBlockSizeValue
-}
-
-// EraseBlockSize returns the smallest erasable area on this particular chip
-// in bytes. This is used for the block size in EraseBlocks.
-func (f flashBlockDevice) EraseBlockSize() int64 {
-	return eraseBlockSize()
-}
-
-// EraseBlocks erases the given number of blocks. An implementation may
-// transparently coalesce ranges of blocks into larger bundles if the chip
-// supports this. The start and len parameters are in block numbers, use
-// EraseBlockSize to map addresses to blocks.
-func (f flashBlockDevice) EraseBlocks(start, length int64) error {
+func (f flashBlockDevice) eraseBlocks(start, length int64) error {
 	address := writeAddress(start * f.EraseBlockSize())
 	if address+uintptr(C.XIP_BASE) > FlashDataEnd() {
 		return errFlashCannotErasePastEOF
@@ -233,24 +176,3 @@ func (f flashBlockDevice) EraseBlocks(start, length int64) error {
 
 	return nil
 }
-
-// pad data if needed so it is long enough for correct byte alignment on writes.
-func (f flashBlockDevice) pad(p []byte) []byte {
-	overflow := int64(len(p)) % f.WriteBlockSize()
-	if overflow == 0 {
-		return p
-	}
-
-	padding := bytes.Repeat([]byte{0xff}, int(f.WriteBlockSize()-overflow))
-	return append(p, padding...)
-}
-
-// return the correct address to be used for write
-func writeAddress(off int64) uintptr {
-	return readAddress(off) - uintptr(C.XIP_BASE)
-}
-
-// return the correct address to be used for reads
-func readAddress(off int64) uintptr {
-	return FlashDataStart() + uintptr(off)
-}

src/machine/machine_rp2040_uart.go

@@ -86,9 +86,10 @@ func (uart *UART) SetBaudRate(br uint32) {
 }
 
 // WriteByte writes a byte of data to the UART.
-func (uart *UART) WriteByte(c byte) error {
+func (uart *UART) writeByte(c byte) error {
 	// wait until buffer is not full
 	for uart.Bus.UARTFR.HasBits(rp.UART0_UARTFR_TXFF) {
+		gosched()
 	}
 
 	// write data
@@ -96,6 +97,12 @@ func (uart *UART) WriteByte(c byte) error {
 	return nil
 }
 
+func (uart *UART) flush() {
+	for uart.Bus.UARTFR.HasBits(rp.UART0_UARTFR_BUSY) {
+		gosched()
+	}
+}
+
 // SetFormat for number of data bits, stop bits, and parity for the UART.
 func (uart *UART) SetFormat(databits, stopbits uint8, parity UARTParity) error {
 	var pen, pev uint8

src/machine/machine_rp2040_usb_fix_usb_device_enumeration.go

@@ -3,6 +3,7 @@
 package machine
 
 import (
+	"device/arm"
 	"device/rp"
 )
 
@@ -87,6 +88,7 @@ func hw_enumeration_fix_force_ls_j() {
 	rp.USBCTRL_REGS.USB_MUXING.Set(rp.USBCTRL_REGS_USB_MUXING_TO_DIGITAL_PAD | rp.USBCTRL_REGS_USB_MUXING_SOFTCON)
 
 	// LS_J is now forced but while loop here just to check
+	waitCycles(125000)
 
 	// if timer pool disabled, or no timer available, have to busy wait.
 	hw_enumeration_fix_finish()
@@ -109,3 +111,10 @@ func hw_enumeration_fix_finish() {
 	// Restore the pad ctrl value
 	padsBank0.io[dp].Set(padCtrlPrev)
 }
+
+func waitCycles(n int) {
+	for n > 0 {
+		arm.Asm("nop")
+		n--
+	}
+}

src/machine/machine_rp2040_watchdog.go

@@ -4,24 +4,67 @@ package machine
 
 import (
 	"device/rp"
-	"runtime/volatile"
-	"unsafe"
 )
 
-type watchdogType struct {
-	ctrl    volatile.Register32
-	load    volatile.Register32
-	reason  volatile.Register32
-	scratch [8]volatile.Register32
-	tick    volatile.Register32
+// Watchdog provides access to the hardware watchdog available
+// in the RP2040.
+var Watchdog = &watchdogImpl{}
+
+const (
+	// WatchdogMaxTimeout in milliseconds (approx 8.3s).
+	//
+	// Nominal 1us per watchdog tick, 24-bit counter,
+	// but due to errata two ticks consumed per 1us.
+	// See: Errata RP2040-E1
+	WatchdogMaxTimeout = (rp.WATCHDOG_LOAD_LOAD_Msk / 1000) / 2
+)
+
+type watchdogImpl struct {
+	// The value to reset the counter to on each Update
+	loadValue uint32
 }
 
-var watchdog = (*watchdogType)(unsafe.Pointer(rp.WATCHDOG))
+// Configure the watchdog.
+//
+// This method should not be called after the watchdog is started and on
+// some platforms attempting to reconfigure after starting the watchdog
+// is explicitly forbidden / will not work.
+func (wd *watchdogImpl) Configure(config WatchdogConfig) error {
+	// x2 due to errata RP2040-E1
+	wd.loadValue = config.TimeoutMillis * 1000 * 2
+	if wd.loadValue > rp.WATCHDOG_LOAD_LOAD_Msk {
+		wd.loadValue = rp.WATCHDOG_LOAD_LOAD_Msk
+	}
+
+	rp.WATCHDOG.CTRL.ClearBits(rp.WATCHDOG_CTRL_ENABLE)
+
+	// Reset everything apart from ROSC and XOSC
+	rp.PSM.WDSEL.Set(0x0001ffff &^ (rp.PSM_WDSEL_ROSC | rp.PSM_WDSEL_XOSC))
+
+	// Pause watchdog during debug
+	rp.WATCHDOG.CTRL.SetBits(rp.WATCHDOG_CTRL_PAUSE_DBG0 | rp.WATCHDOG_CTRL_PAUSE_DBG1 | rp.WATCHDOG_CTRL_PAUSE_JTAG)
+
+	// Load initial counter
+	rp.WATCHDOG.LOAD.Set(wd.loadValue)
+
+	return nil
+}
+
+// Starts the watchdog.
+func (wd *watchdogImpl) Start() error {
+	rp.WATCHDOG.CTRL.SetBits(rp.WATCHDOG_CTRL_ENABLE)
+	return nil
+}
+
+// Update the watchdog, indicating that the app is healthy.
+func (wd *watchdogImpl) Update() {
+	rp.WATCHDOG.LOAD.Set(wd.loadValue)
+}
 
 // startTick starts the watchdog tick.
 // cycles needs to be a divider that when applied to the xosc input,
 // produces a 1MHz clock. So if the xosc frequency is 12MHz,
 // this will need to be 12.
-func (wd *watchdogType) startTick(cycles uint32) {
-	wd.tick.Set(cycles | rp.WATCHDOG_TICK_ENABLE)
+func (wd *watchdogImpl) startTick(cycles uint32) {
+	rp.WATCHDOG.TICK.Set(cycles | rp.WATCHDOG_TICK_ENABLE)
 }

src/machine/machine_stm32_iwdg.go

@@ -0,0 +1,66 @@
+//go:build stm32
+
+package machine
+
+import "device/stm32"
+
+var (
+	Watchdog = &watchdogImpl{}
+)
+
+const (
+	// WatchdogMaxTimeout in milliseconds (32.768s)
+	//
+	// Timeout is based on 12-bit counter with /256 divider on
+	// 32.768kHz clock.  See 21.3.3 of RM0090 for table.
+	WatchdogMaxTimeout = ((0xfff + 1) * 256 * 1024) / 32768
+)
+
+const (
+	// Enable access to PR, RLR and WINR registers (0x5555)
+	iwdgKeyEnable = 0x5555
+	// Reset the watchdog value (0xAAAA)
+	iwdgKeyReset = 0xaaaa
+	// Start the watchdog (0xCCCC)
+	iwdgKeyStart = 0xcccc
+	// Divide by 256
+	iwdgDiv256 = 6
+)
+
+type watchdogImpl struct {
+}
+
+// Configure the watchdog.
+//
+// This method should not be called after the watchdog is started and on
+// some platforms attempting to reconfigure after starting the watchdog
+// is explicitly forbidden / will not work.
+func (wd *watchdogImpl) Configure(config WatchdogConfig) error {
+
+	// Enable configuration of IWDG
+	stm32.IWDG.KR.Set(iwdgKeyEnable)
+
+	// Unconditionally divide by /256 since we don't really need accuracy
+	// less than 8ms
+	stm32.IWDG.PR.Set(iwdgDiv256)
+
+	timeout := config.TimeoutMillis
+	if timeout > WatchdogMaxTimeout {
+		timeout = WatchdogMaxTimeout
+	}
+
+	// Set reload value based on /256 divider
+	stm32.IWDG.RLR.Set(((config.TimeoutMillis*32768 + (256 * 1024) - 1) / (256 * 1024)) - 1)
+	return nil
+}
+
+// Starts the watchdog.
+func (wd *watchdogImpl) Start() error {
+	stm32.IWDG.KR.Set(iwdgKeyStart)
+	return nil
+}
+
+// Update the watchdog, indicating that `source` is healthy.
+func (wd *watchdogImpl) Update() {
+	stm32.IWDG.KR.Set(iwdgKeyReset)
+}

src/machine/machine_stm32_uart.go

@@ -74,10 +74,12 @@ func (uart *UART) SetBaudRate(br uint32) {
 }
 
 // WriteByte writes a byte of data to the UART.
-func (uart *UART) WriteByte(c byte) error {
+func (uart *UART) writeByte(c byte) error {
 	uart.txReg.Set(uint32(c))
 
 	for !uart.statusReg.HasBits(uart.txEmptyFlag) {
 	}
 	return nil
 }
+
+func (uart *UART) flush() {}

src/machine/uart.go

@@ -59,11 +59,27 @@ func (uart *UART) Read(data []byte) (n int, err error) {
 	return size, nil
 }
 
-// Write data to the UART.
-func (uart *UART) Write(data []byte) (n int, err error) {
-	for _, v := range data {
-		uart.WriteByte(v)
+// WriteByte writes a byte of data over the UART's Tx.
+// This function blocks until the data is finished being sent.
+func (uart *UART) WriteByte(c byte) error {
+	err := uart.writeByte(c)
+	if err != nil {
+		return err
 	}
+	uart.flush() // flush() blocks until all data has been transmitted.
+	return nil
+}
+
+// Write data over the UART's Tx.
+// This function blocks until the data is finished being sent.
+func (uart *UART) Write(data []byte) (n int, err error) {
+	for i, v := range data {
+		err = uart.writeByte(v)
+		if err != nil {
+			return i, err
+		}
+	}
+	uart.flush() // flush() blocks until all data has been transmitted.
 	return len(data), nil
 }
 

src/machine/usb.go

@@ -29,9 +29,7 @@ type Serialer interface {
 	RTS() bool
 }
 
-var usbDescriptor = descriptor.CDC
-
-var usbDescriptorConfig uint8 = usb.DescriptorConfigCDC
+var usbDescriptor descriptor.Descriptor
 
 func usbVendorID() uint16 {
 	if usb.VendorID != 0 {
@@ -138,18 +136,6 @@ func sendDescriptor(setup usb.Setup) {
 		sendUSBPacket(0, usbDescriptor.Configuration, setup.WLength)
 		return
 	case descriptor.TypeDevice:
-		// composite descriptor
-		switch {
-		case (usbDescriptorConfig & usb.DescriptorConfigHID) > 0:
-			usbDescriptor = descriptor.CDCHID
-		case (usbDescriptorConfig & usb.DescriptorConfigMIDI) > 0:
-			usbDescriptor = descriptor.CDCMIDI
-		case (usbDescriptorConfig & usb.DescriptorConfigJoystick) > 0:
-			usbDescriptor = descriptor.CDCJoystick
-		default:
-			usbDescriptor = descriptor.CDC
-		}
-
 		usbDescriptor.Configure(usbVendorID(), usbProductID())
 		sendUSBPacket(0, usbDescriptor.Device, setup.WLength)
 		return
@@ -273,48 +259,56 @@ func handleStandardSetup(setup usb.Setup) bool {
 }
 
 func EnableCDC(txHandler func(), rxHandler func([]byte), setupHandler func(usb.Setup) bool) {
-	usbDescriptorConfig |= usb.DescriptorConfigCDC
-	endPoints[usb.CDC_ENDPOINT_ACM] = (usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointIn)
-	endPoints[usb.CDC_ENDPOINT_OUT] = (usb.ENDPOINT_TYPE_BULK | usb.EndpointOut)
-	endPoints[usb.CDC_ENDPOINT_IN] = (usb.ENDPOINT_TYPE_BULK | usb.EndpointIn)
-	usbRxHandler[usb.CDC_ENDPOINT_OUT] = rxHandler
-	usbTxHandler[usb.CDC_ENDPOINT_IN] = txHandler
-	usbSetupHandler[usb.CDC_ACM_INTERFACE] = setupHandler // 0x02 (Communications and CDC Control)
-	usbSetupHandler[usb.CDC_DATA_INTERFACE] = nil         // 0x0A (CDC-Data)
+	if len(usbDescriptor.Device) == 0 {
+		usbDescriptor = descriptor.CDC
+	}
+	// Initialization of endpoints is required even for non-CDC
+	ConfigureUSBEndpoint(usbDescriptor,
+		[]usb.EndpointConfig{
+			{
+				Index: usb.CDC_ENDPOINT_ACM,
+				IsIn:  true,
+				Type:  usb.ENDPOINT_TYPE_INTERRUPT,
+			},
+			{
+				Index:     usb.CDC_ENDPOINT_OUT,
+				IsIn:      false,
+				Type:      usb.ENDPOINT_TYPE_BULK,
+				RxHandler: rxHandler,
+			},
+			{
+				Index:     usb.CDC_ENDPOINT_IN,
+				IsIn:      true,
+				Type:      usb.ENDPOINT_TYPE_BULK,
+				TxHandler: txHandler,
+			},
+		},
+		[]usb.SetupConfig{
+			{
+				Index:   usb.CDC_ACM_INTERFACE,
+				Handler: setupHandler,
+			},
+		})
 }
 
-// EnableHID enables HID. This function must be executed from the init().
-func EnableHID(txHandler func(), rxHandler func([]byte), setupHandler func(usb.Setup) bool) {
-	usbDescriptorConfig |= usb.DescriptorConfigHID
-	endPoints[usb.HID_ENDPOINT_IN] = (usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointIn)
-	usbTxHandler[usb.HID_ENDPOINT_IN] = txHandler
-	usbSetupHandler[usb.HID_INTERFACE] = setupHandler // 0x03 (HID - Human Interface Device)
-}
+func ConfigureUSBEndpoint(desc descriptor.Descriptor, epSettings []usb.EndpointConfig, setup []usb.SetupConfig) {
+	usbDescriptor = desc
 
-// EnableMIDI enables MIDI. This function must be executed from the init().
-func EnableMIDI(txHandler func(), rxHandler func([]byte), setupHandler func(usb.Setup) bool) {
-	usbDescriptorConfig |= usb.DescriptorConfigMIDI
-	endPoints[usb.MIDI_ENDPOINT_OUT] = (usb.ENDPOINT_TYPE_BULK | usb.EndpointOut)
-	endPoints[usb.MIDI_ENDPOINT_IN] = (usb.ENDPOINT_TYPE_BULK | usb.EndpointIn)
-	usbRxHandler[usb.MIDI_ENDPOINT_OUT] = rxHandler
-	usbTxHandler[usb.MIDI_ENDPOINT_IN] = txHandler
-}
-
-// EnableJoystick enables HID. This function must be executed from the init().
-func EnableJoystick(txHandler func(), rxHandler func([]byte), setupHandler func(usb.Setup) bool, hidDesc []byte) {
-	class, err := descriptor.FindClassHIDType(descriptor.CDCJoystick.Configuration, descriptor.ClassHIDJoystick.Bytes())
-	if err != nil {
-		// TODO: some way to notify about error
-		return
+	for _, ep := range epSettings {
+		if ep.IsIn {
+			endPoints[ep.Index] = uint32(ep.Type | usb.EndpointIn)
+			if ep.TxHandler != nil {
+				usbTxHandler[ep.Index] = ep.TxHandler
+			}
+		} else {
+			endPoints[ep.Index] = uint32(ep.Type | usb.EndpointOut)
+			if ep.RxHandler != nil {
+				usbRxHandler[ep.Index] = ep.RxHandler
+			}
+		}
 	}
 
-	class.ClassLength(uint16(len(hidDesc)))
-	descriptor.CDCJoystick.HID[2] = hidDesc
-
-	usbDescriptorConfig |= usb.DescriptorConfigJoystick
-	endPoints[usb.HID_ENDPOINT_OUT] = (usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointOut)
-	usbRxHandler[usb.HID_ENDPOINT_OUT] = rxHandler
-	endPoints[usb.HID_ENDPOINT_IN] = (usb.ENDPOINT_TYPE_INTERRUPT | usb.EndpointIn)
-	usbTxHandler[usb.HID_ENDPOINT_IN] = txHandler
-	usbSetupHandler[usb.HID_INTERFACE] = setupHandler // 0x03 (HID - Human Interface Device)
+	for _, s := range setup {
+		usbSetupHandler[s.Index] = s.Handler
+	}
 }

src/machine/usb/adc/midi/midi.go

@@ -3,6 +3,7 @@ package midi
 import (
 	"machine"
 	"machine/usb"
+	"machine/usb/descriptor"
 )
 
 const (
@@ -40,7 +41,23 @@ func newMidi() *midi {
 	m := &midi{
 		buf: NewRingBuffer(),
 	}
-	machine.EnableMIDI(m.Handler, m.RxHandler, nil)
+	machine.ConfigureUSBEndpoint(descriptor.CDCMIDI,
+		[]usb.EndpointConfig{
+			{
+				Index:     usb.MIDI_ENDPOINT_OUT,
+				IsIn:      false,
+				Type:      usb.ENDPOINT_TYPE_BULK,
+				RxHandler: m.RxHandler,
+			},
+			{
+				Index:     usb.MIDI_ENDPOINT_IN,
+				IsIn:      true,
+				Type:      usb.ENDPOINT_TYPE_BULK,
+				TxHandler: m.Handler,
+			},
+		},
+		[]usb.SetupConfig{},
+	)
 	return m
 }
 

src/machine/usb/config.go

@@ -0,0 +1,14 @@
+package usb
+
+type EndpointConfig struct {
+	Index     uint8
+	IsIn      bool
+	TxHandler func()
+	RxHandler func([]byte)
+	Type      uint8
+}
+
+type SetupConfig struct {
+	Index   uint8
+	Handler func(Setup) bool
+}

src/machine/usb/descriptor/hid.go

@@ -26,7 +26,7 @@ var interfaceHID = [interfaceTypeLen]byte{
 	TypeInterface,
 	0x02, // InterfaceNumber
 	0x00, // AlternateSetting
-	0x01, // NumEndpoints
+	0x02, // NumEndpoints
 	0x03, // InterfaceClass
 	0x00, // InterfaceSubClass
 	0x00, // InterfaceProtocol
@@ -103,7 +103,7 @@ var classHID = [ClassHIDTypeLen]byte{
 	0x00, // CountryCode
 	0x01, // NumDescriptors
 	0x22, // ClassType
-	0x7E, // ClassLength L
+	0x90, // ClassLength L
 	0x00, // ClassLength H
 }
 
@@ -128,6 +128,7 @@ var CDCHID = Descriptor{
 		InterfaceHID.Bytes(),
 		ClassHID.Bytes(),
 		EndpointEP4IN.Bytes(),
+		EndpointEP5OUT.Bytes(),
 	}),
 	HID: map[uint16][]byte{
 		2: Append([][]byte{
@@ -147,6 +148,15 @@ var CDCHID = Descriptor{
 			HIDReportCount(1),
 			HIDReportSize(8),
 			HIDInputConstVarAbs,
+			HIDReportCount(3),
+			HIDReportSize(1),
+			HIDUsagePageLED,
+			HIDUsageMinimum(1),
+			HIDUsageMaximum(3),
+			HIDOutputDataVarAbs,
+			HIDReportCount(5),
+			HIDReportSize(1),
+			HIDOutputConstVarAbs,
 			HIDReportCount(6),
 			HIDReportSize(8),
 			HIDLogicalMinimum(0),

src/machine/usb/descriptor/hidreport.go

@@ -3,21 +3,29 @@ package descriptor
 const (
 	hidUsagePage       = 0x05
 	hidUsage           = 0x09
-	hidLogicalMinimum  = 0x15
-	hidLogicalMaximum  = 0x25
-	hidUsageMinimum    = 0x19
-	hidUsageMaximum    = 0x29
-	hidPhysicalMinimum = 0x35
-	hidPhysicalMaximum = 0x46
+	hidLogicalMinimum  = 0x14
+	hidLogicalMaximum  = 0x24
+	hidUsageMinimum    = 0x18
+	hidUsageMaximum    = 0x28
+	hidPhysicalMinimum = 0x34
+	hidPhysicalMaximum = 0x44
 	hidUnitExponent    = 0x55
 	hidUnit            = 0x65
 	hidCollection      = 0xa1
 	hidInput           = 0x81
+	hidOutput          = 0x91
 	hidReportSize      = 0x75
 	hidReportCount     = 0x95
 	hidReportID        = 0x85
 )
 
+const (
+	hidSizeValue0 = 0x00
+	hidSizeValue1 = 0x01
+	hidSizeValue2 = 0x02
+	hidSizeValue4 = 0x03
+)
+
 var (
 	HIDUsagePageGenericDesktop     = []byte{hidUsagePage, 0x01}
 	HIDUsagePageSimulationControls = []byte{hidUsagePage, 0x02}
@@ -114,6 +122,12 @@ var (
 
 	// Input (Data, Variable, Relative), 2 position bytes (X & Y)
 	HIDInputDataVarRel = []byte{hidInput, 0x06}
+
+	// Output (Data, Variable, Absolute), Modifier byte
+	HIDOutputDataVarAbs = []byte{hidOutput, 0x02}
+
+	// Output (Const, Variable, Absolute), Modifier byte
+	HIDOutputConstVarAbs = []byte{hidOutput, 0x03}
 )
 
 func HIDReportSize(size int) []byte {
@@ -129,51 +143,69 @@ func HIDReportID(id int) []byte {
 }
 
 func HIDLogicalMinimum(min int) []byte {
-	if min > 255 {
-		return []byte{hidLogicalMinimum + 1, uint8(min), uint8(min >> 8)}
+	switch {
+	case min < -32767 || 65535 < min:
+		return []byte{hidLogicalMinimum + hidSizeValue4, uint8(min), uint8(min >> 8), uint8(min >> 16), uint8(min >> 24)}
+	case min < -127 || 255 < min:
+		return []byte{hidLogicalMinimum + hidSizeValue2, uint8(min), uint8(min >> 8)}
+	default:
+		return []byte{hidLogicalMinimum + hidSizeValue1, byte(min)}
 	}
-
-	return []byte{hidLogicalMinimum, byte(min)}
 }
 
 func HIDLogicalMaximum(max int) []byte {
-	if max > 255 {
-		return []byte{hidLogicalMaximum + 1, uint8(max), uint8(max >> 8)}
+	switch {
+	case max < -32767 || 65535 < max:
+		return []byte{hidLogicalMaximum + hidSizeValue4, uint8(max), uint8(max >> 8), uint8(max >> 16), uint8(max >> 24)}
+	case max < -127 || 255 < max:
+		return []byte{hidLogicalMaximum + hidSizeValue2, uint8(max), uint8(max >> 8)}
+	default:
+		return []byte{hidLogicalMaximum + hidSizeValue1, byte(max)}
 	}
-
-	return []byte{hidLogicalMaximum, byte(max)}
 }
 
 func HIDUsageMinimum(min int) []byte {
-	if min > 255 {
-		return []byte{hidUsageMinimum + 1, uint8(min), uint8(min >> 8)}
+	switch {
+	case min < -32767 || 65535 < min:
+		return []byte{hidUsageMinimum + hidSizeValue4, uint8(min), uint8(min >> 8), uint8(min >> 16), uint8(min >> 24)}
+	case min < -127 || 255 < min:
+		return []byte{hidUsageMinimum + hidSizeValue2, uint8(min), uint8(min >> 8)}
+	default:
+		return []byte{hidUsageMinimum + hidSizeValue1, byte(min)}
 	}
-
-	return []byte{hidUsageMinimum, byte(min)}
 }
 
 func HIDUsageMaximum(max int) []byte {
-	if max > 255 {
-		return []byte{hidUsageMaximum + 1, uint8(max), uint8(max >> 8)}
+	switch {
+	case max < -32767 || 65535 < max:
+		return []byte{hidUsageMaximum + hidSizeValue4, uint8(max), uint8(max >> 8), uint8(max >> 16), uint8(max >> 24)}
+	case max < -127 || 255 < max:
+		return []byte{hidUsageMaximum + hidSizeValue2, uint8(max), uint8(max >> 8)}
+	default:
+		return []byte{hidUsageMaximum + hidSizeValue1, byte(max)}
 	}
-
-	return []byte{hidUsageMaximum, byte(max)}
 }
 
 func HIDPhysicalMinimum(min int) []byte {
-	if min > 255 {
-		return []byte{hidPhysicalMinimum + 1, uint8(min), uint8(min >> 8)}
+	switch {
+	case min < -32767 || 65535 < min:
+		return []byte{hidPhysicalMinimum + hidSizeValue4, uint8(min), uint8(min >> 8), uint8(min >> 16), uint8(min >> 24)}
+	case min < -127 || 255 < min:
+		return []byte{hidPhysicalMinimum + hidSizeValue2, uint8(min), uint8(min >> 8)}
+	default:
+		return []byte{hidPhysicalMinimum + hidSizeValue1, byte(min)}
 	}
-
-	return []byte{hidPhysicalMinimum, byte(min)}
 }
 
 func HIDPhysicalMaximum(max int) []byte {
-	if max > 255 {
-		return []byte{hidPhysicalMaximum + 1, uint8(max), uint8(max >> 8)}
+	switch {
+	case max < -32767 || 65535 < max:
+		return []byte{hidPhysicalMaximum + hidSizeValue4, uint8(max), uint8(max >> 8), uint8(max >> 16), uint8(max >> 24)}
+	case max < -127 || 255 < max:
+		return []byte{hidPhysicalMaximum + hidSizeValue2, uint8(max), uint8(max >> 8)}
+	default:
+		return []byte{hidPhysicalMaximum + hidSizeValue1, byte(max)}
 	}
-
-	return []byte{hidPhysicalMaximum, byte(max)}
 }
 
 func HIDUnitExponent(exp int) []byte {

src/machine/usb/descriptor/joystick.go

@@ -80,10 +80,7 @@ var JoystickDefaultHIDReport = Append([][]byte{
 	HIDLogicalMaximum(1),
 	HIDReportSize(1),
 	HIDReportCount(16),
-	HIDInputDataVarAbs,
-	HIDReportCount(1),
-	HIDReportSize(3),
-	HIDUnitExponent(-16),
+	HIDUnitExponent(0),
 	HIDUnit(0),
 	HIDInputDataVarAbs,
 

src/machine/usb/hid/hid.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"machine"
 	"machine/usb"
+	"machine/usb/descriptor"
 )
 
 // from usb-hid.go
@@ -22,7 +23,8 @@ const (
 )
 
 type hidDevicer interface {
-	Handler() bool
+	TxHandler() bool
+	RxHandler([]byte) bool
 }
 
 var devices [5]hidDevicer
@@ -32,19 +34,50 @@ var size int
 // calls machine.EnableHID for USB configuration
 func SetHandler(d hidDevicer) {
 	if size == 0 {
-		machine.EnableHID(handler, nil, setupHandler)
+		machine.ConfigureUSBEndpoint(descriptor.CDCHID,
+			[]usb.EndpointConfig{
+				{
+					Index:     usb.HID_ENDPOINT_OUT,
+					IsIn:      false,
+					Type:      usb.ENDPOINT_TYPE_INTERRUPT,
+					RxHandler: rxHandler,
+				},
+				{
+					Index:     usb.HID_ENDPOINT_IN,
+					IsIn:      true,
+					Type:      usb.ENDPOINT_TYPE_INTERRUPT,
+					TxHandler: txHandler,
+				},
+			},
+			[]usb.SetupConfig{
+				{
+					Index:   usb.HID_INTERFACE,
+					Handler: setupHandler,
+				},
+			})
 	}
 
 	devices[size] = d
 	size++
 }
 
-func handler() {
+func txHandler() {
 	for _, d := range devices {
 		if d == nil {
 			continue
 		}
-		if done := d.Handler(); done {
+		if done := d.TxHandler(); done {
+			return
+		}
+	}
+}
+
+func rxHandler(b []byte) {
+	for _, d := range devices {
+		if d == nil {
+			continue
+		}
+		if done := d.RxHandler(b); done {
 			return
 		}
 	}

src/machine/usb/hid/joystick/joystick.go

@@ -3,6 +3,7 @@ package joystick
 import (
 	"machine"
 	"machine/usb"
+	"machine/usb/descriptor"
 	"machine/usb/hid"
 )
 
@@ -32,18 +33,50 @@ func UseSettings(def Definitions, rxHandlerFunc func(b []byte), setupFunc func(s
 	if setupFunc == nil {
 		setupFunc = hid.DefaultSetupHandler
 	}
-	machine.EnableJoystick(js.handler, rxHandlerFunc, setupFunc, hidDesc)
+	if rxHandlerFunc == nil {
+		rxHandlerFunc = js.rxHandlerFunc
+	}
+	if len(hidDesc) == 0 {
+		hidDesc = descriptor.JoystickDefaultHIDReport
+	}
+	class, err := descriptor.FindClassHIDType(descriptor.CDCJoystick.Configuration, descriptor.ClassHIDJoystick.Bytes())
+	if err != nil {
+		// TODO: some way to notify about error
+		return nil
+	}
+
+	class.ClassLength(uint16(len(hidDesc)))
+	descriptor.CDCJoystick.HID[2] = hidDesc
+
+	machine.ConfigureUSBEndpoint(descriptor.CDCJoystick,
+		[]usb.EndpointConfig{
+			{
+				Index:     usb.HID_ENDPOINT_OUT,
+				IsIn:      false,
+				Type:      usb.ENDPOINT_TYPE_INTERRUPT,
+				RxHandler: rxHandlerFunc,
+			},
+			{
+				Index:     usb.HID_ENDPOINT_IN,
+				IsIn:      true,
+				Type:      usb.ENDPOINT_TYPE_INTERRUPT,
+				TxHandler: js.handler,
+			},
+		},
+		[]usb.SetupConfig{
+			{
+				Index:   usb.HID_INTERFACE,
+				Handler: setupFunc,
+			},
+		},
+	)
 	Joystick = js
 	return js
 }
 
 func newDefaultJoystick() *joystick {
 	def := DefaultDefinitions()
-	js := &joystick{
-		State: def.NewState(),
-		buf:   hid.NewRingBuffer(),
-	}
-	machine.EnableJoystick(js.handler, js.rxHandler, hid.DefaultSetupHandler, def.Descriptor())
+	js := UseSettings(def, nil, nil, nil)
 	return js
 }
 

src/machine/usb/hid/keyboard/keyboard.go

@@ -81,7 +81,7 @@ func newKeyboard() *keyboard {
 	}
 }
 
-func (kb *keyboard) Handler() bool {
+func (kb *keyboard) TxHandler() bool {
 	kb.waitTxc = false
 	if b, ok := kb.buf.Get(); ok {
 		kb.waitTxc = true
@@ -91,6 +91,13 @@ func (kb *keyboard) Handler() bool {
 	return false
 }
 
+func (kb *keyboard) RxHandler(b []byte) bool {
+	if len(b) >= 2 && b[0] == 2 /* ReportID */ {
+		kb.led = b[1]
+	}
+	return false
+}
+
 func (kb *keyboard) tx(b []byte) {
 	if machine.USBDev.InitEndpointComplete {
 		if kb.waitTxc {
@@ -102,6 +109,18 @@ func (kb *keyboard) tx(b []byte) {
 	}
 }
 
+func (kb *keyboard) NumLockLed() bool {
+	return kb.led&1 != 0
+}
+
+func (kb *keyboard) CapsLockLed() bool {
+	return kb.led&2 != 0
+}
+
+func (kb *keyboard) ScrollLockLed() bool {
+	return kb.led&4 != 0
+}
+
 func (kb *keyboard) ready() bool {
 	return true
 }

src/machine/usb/hid/mouse/mouse.go

@@ -47,7 +47,7 @@ func newMouse() *mouse {
 	}
 }
 
-func (m *mouse) Handler() bool {
+func (m *mouse) TxHandler() bool {
 	m.waitTxc = false
 	if b, ok := m.buf.Get(); ok {
 		m.waitTxc = true
@@ -57,6 +57,10 @@ func (m *mouse) Handler() bool {
 	return false
 }
 
+func (m *mouse) RxHandler(b []byte) bool {
+	return false
+}
+
 func (m *mouse) tx(b []byte) {
 	if machine.USBDev.InitEndpointComplete {
 		if m.waitTxc {

src/machine/watchdog.go

@@ -0,0 +1,34 @@
+//go:build nrf52840 || nrf52833 || rp2040 || atsamd51 || atsame5x || stm32
+
+package machine
+
+// WatchdogConfig holds configuration for the watchdog timer.
+type WatchdogConfig struct {
+	// The timeout (in milliseconds) before the watchdog fires.
+	//
+	// If the requested timeout exceeds `MaxTimeout` it will be rounded
+	// down.
+	TimeoutMillis uint32
+}
+
+// watchdog must be implemented by any platform supporting watchdog functionality
+type watchdog interface {
+	// Configure the watchdog.
+	//
+	// This method should not be called after the watchdog is started and on
+	// some platforms attempting to reconfigure after starting the watchdog
+	// is explicitly forbidden / will not work.
+	Configure(config WatchdogConfig) error
+
+	// Starts the watchdog.
+	Start() error
+
+	// Update the watchdog, indicating that the app is healthy.
+	Update()
+}
+
+// Ensure required public symbols var exists and meets interface spec
+var _ = watchdog(Watchdog)
+
+// Ensure required public constants exist
+const _ = WatchdogMaxTimeout

src/os/dir_unix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build linux && !baremetal && !wasi
+//go:build linux && !baremetal && !wasi && !wasip1
 
 package os
 

src/os/dir_wasi.go

@@ -6,7 +6,7 @@
 // fairly similar: we use fdopendir, fdclosedir, and readdir from wasi-libc in
 // a similar way that the darwin code uses functions from libc.
 
-//go:build wasi
+//go:build wasi || wasip1
 
 package os
 
@@ -53,9 +53,6 @@ func (f *File) readdir(n int, mode readdirMode) (names []string, dirents []DirEn
 		if dirent == nil { // EOF
 			break
 		}
-		if dirent.Ino == 0 {
-			continue
-		}
 		name := dirent.Name()
 		// Check for useless names before allocating a string.
 		if string(name) == "." || string(name) == ".." {

src/os/env_unix_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build darwin || linux
+//go:build darwin || linux || wasip1
 
 package os_test
 

src/os/errors.go

@@ -32,6 +32,10 @@ var (
 // The following code is copied from the official implementation.
 // src/internal/poll/fd.go
 
+// ErrNoDeadline is returned when a request is made to set a deadline
+// on a file type that does not use the poller.
+var ErrNoDeadline = errors.New("file type does not support deadline")
+
 // ErrDeadlineExceeded is returned for an expired deadline.
 // This is exported by the os package as os.ErrDeadlineExceeded.
 var ErrDeadlineExceeded error = &DeadlineExceededError{}

src/os/exec_posix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build aix || darwin || dragonfly || freebsd || (js && wasm) || linux || netbsd || openbsd || solaris || windows
+//go:build aix || darwin || dragonfly || freebsd || (js && wasm) || linux || netbsd || openbsd || solaris || wasip1 || windows
 
 package os
 

src/os/file_other.go

@@ -1,4 +1,4 @@
-//go:build baremetal || (wasm && !wasi)
+//go:build baremetal || (wasm && !wasi && !wasip1)
 
 package os
 

src/os/file_unix.go

@@ -1,4 +1,4 @@
-//go:build darwin || (linux && !baremetal)
+//go:build darwin || (linux && !baremetal) || wasip1
 
 // target wasi sets GOOS=linux and thus the +linux build tag,
 // even though it doesn't show up in "tinygo info target -wasi"

src/os/getpagesize_test.go

@@ -1,4 +1,4 @@
-//go:build windows || darwin || (linux && !baremetal)
+//go:build windows || darwin || (linux && !baremetal) || wasip1
 
 package os_test
 

src/os/is_wasi_no_test.go

@@ -1,4 +1,4 @@
-//go:build !wasi
+//go:build !wasi && !wasip1
 
 package os_test
 

src/os/is_wasi_test.go

@@ -1,4 +1,4 @@
-//go:build wasi
+//go:build wasi || wasip1
 
 package os_test
 

src/os/os_anyos_test.go

@@ -1,4 +1,4 @@
-//go:build windows || darwin || (linux && !baremetal)
+//go:build windows || darwin || (linux && !baremetal) || wasip1
 
 package os_test
 
@@ -23,7 +23,6 @@ var dot = []string{
 	"os_test.go",
 	"types.go",
 	"stat_darwin.go",
-	"stat_linux.go",
 }
 
 func randomName() string {

src/os/os_chmod_test.go

@@ -1,4 +1,4 @@
-//go:build !baremetal && !js && !wasi
+//go:build !baremetal && !js && !wasi && !wasip1
 
 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

src/os/os_symlink_test.go

@@ -1,4 +1,4 @@
-//go:build !windows && !baremetal && !js && !wasi
+//go:build !windows && !baremetal && !js && !wasi && !wasip1
 
 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

src/os/read_test.go

@@ -1,4 +1,4 @@
-//go:build !baremetal && !js && !wasi
+//go:build !baremetal && !js && !wasi && !wasip1
 
 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

src/os/removeall_noat.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !baremetal && !js && !wasi
+//go:build !baremetal && !js && !wasi && !wasip1
 
 package os
 

src/os/removeall_other.go

@@ -1,4 +1,4 @@
-//go:build baremetal || js || wasi
+//go:build baremetal || js || wasi || wasip1
 
 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

src/os/stat_linuxlike.go

@@ -1,9 +1,13 @@
-//go:build linux && !baremetal
+//go:build (linux && !baremetal) || wasip1
 
 // 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.
 
+// Note: this file is used for both Linux and WASI.
+// Eventually it might be better to spit it up, and make the syscall constants
+// match the typical WASI constants instead of the Linux-equivalents used here.
+
 package os
 
 import (

src/os/stat_other.go

@@ -1,4 +1,4 @@
-//go:build baremetal || (wasm && !wasi)
+//go:build baremetal || (wasm && !wasi && !wasip1)
 
 // Copyright 2016 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style

src/os/stat_unix.go

@@ -1,4 +1,4 @@
-//go:build darwin || (linux && !baremetal)
+//go:build darwin || (linux && !baremetal) || wasip1
 
 // Copyright 2016 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style