From 9adbde99a2badfa37be8693318467bae43edd88a Mon Sep 17 00:00:00 2001
From: Yurii Soldak <ysoldak@gmail.com>
Date: Thu, 27 May 2021 21:35:00 +0200
Subject: [PATCH] wifinina: avoid fmt package

---
 examples/wifinina/connect/main.go | 16 +++-------------
 wifinina/tcp.go                   | 10 +++++-----
 wifinina/wifinina.go              | 32 ++++++++++++++++++++++---------
 3 files changed, 31 insertions(+), 27 deletions(-)

diff --git a/examples/wifinina/connect/main.go b/examples/wifinina/connect/main.go
index f4bc49a..087eff0 100644
--- a/examples/wifinina/connect/main.go
+++ b/examples/wifinina/connect/main.go
@@ -2,9 +2,8 @@
 package main
 
 import (
-	"encoding/binary"
-	"fmt"
 	"machine"
+	"strconv"
 	"time"
 
 	"tinygo.org/x/drivers/wifinina"
@@ -80,7 +79,7 @@ func printRSSI() {
 		println("Unknown (error: ", err.Error(), ")")
 		return
 	}
-	println(fmt.Sprintf("%d", rssi))
+	println(strconv.Itoa(int(rssi)))
 }
 
 func printIPs() {
@@ -113,20 +112,11 @@ func printTime() {
 
 func printMac() {
 	print("MAC: ")
-	b := make([]byte, 8)
 	mac, err := adaptor.GetMACAddress()
 	if err != nil {
 		println("Unknown (", err.Error(), ")")
 	}
-	binary.LittleEndian.PutUint64(b, uint64(mac))
-	macAddress := ""
-	for i := 5; i >= 0; i-- {
-		macAddress += fmt.Sprintf("%0X", b[i])
-		if i != 0 {
-			macAddress += ":"
-		}
-	}
-	println(macAddress)
+	println(mac.String())
 }
 
 // Wait for user to open serial console
diff --git a/wifinina/tcp.go b/wifinina/tcp.go
index 0ae2ea7..1f09ee0 100644
--- a/wifinina/tcp.go
+++ b/wifinina/tcp.go
@@ -1,7 +1,7 @@
 package wifinina
 
 import (
-	"fmt"
+	"errors"
 	"strconv"
 	"time"
 
@@ -104,7 +104,7 @@ func (drv *Driver) connectSocket(addr, portStr string, mode uint8) error {
 func convertPort(portStr string) (uint16, error) {
 	p64, err := strconv.ParseUint(portStr, 10, 16)
 	if err != nil {
-		return 0, fmt.Errorf("could not convert port to uint16: %w", err)
+		return 0, errors.New("could not convert port to uint16: " + err.Error())
 	}
 	return uint16(p64), nil
 }
@@ -175,13 +175,13 @@ func (drv *Driver) Write(b []byte) (n int, err error) {
 	}
 	if drv.proto == ProtoModeUDP {
 		if err := drv.dev.StartClient("", drv.ip, drv.port, drv.sock, drv.proto); err != nil {
-			return 0, fmt.Errorf("error in startClient: %w", err)
+			return 0, errors.New("error in startClient: " + err.Error())
 		}
 		if _, err := drv.dev.InsertDataBuf(b, drv.sock); err != nil {
-			return 0, fmt.Errorf("error in insertDataBuf: %w", err)
+			return 0, errors.New("error in insertDataBuf: " + err.Error())
 		}
 		if _, err := drv.dev.SendUDPData(drv.sock); err != nil {
-			return 0, fmt.Errorf("error in sendUDPData: %w", err)
+			return 0, errors.New("error in sendUDPData: " + err.Error())
 		}
 		return len(b), nil
 	} else {
diff --git a/wifinina/wifinina.go b/wifinina/wifinina.go
index e7fb926..8b41b2a 100644
--- a/wifinina/wifinina.go
+++ b/wifinina/wifinina.go
@@ -8,7 +8,10 @@ package wifinina // import "tinygo.org/x/drivers/wifinina"
 
 import (
 	"encoding/binary"
-	"fmt"
+	"encoding/hex"
+	"fmt" // used only in debug printouts and is optimized out when debugging is disabled
+	"strconv"
+	"strings"
 	"time"
 
 	"machine"
@@ -213,15 +216,16 @@ func (addr IPAddress) String() string {
 	if len(addr) < 4 {
 		return ""
 	}
-	return fmt.Sprintf("%d.%d.%d.%d", addr[0], addr[1], addr[2], addr[3])
+	return strconv.Itoa(int(addr[0])) + "." + strconv.Itoa(int(addr[1])) + "." + strconv.Itoa(int(addr[2])) + "." + strconv.Itoa(int(addr[3]))
 }
 
 func ParseIPv4(s string) (IPAddress, error) {
-	var v0, v1, v2, v3 uint8
-	if _, err := fmt.Sscanf(s, "%d.%d.%d.%d", &v0, &v1, &v2, &v3); err != nil {
-		return "", err
-	}
-	return IPAddress([]byte{v0, v1, v2, v3}), nil
+	v := strings.Split(s, ".")
+	v0, _ := strconv.Atoi(v[0])
+	v1, _ := strconv.Atoi(v[1])
+	v2, _ := strconv.Atoi(v[2])
+	v3, _ := strconv.Atoi(v[3])
+	return IPAddress([]byte{byte(v0), byte(v1), byte(v2), byte(v3)}), nil
 }
 
 func (addr IPAddress) AsUint32() uint32 {
@@ -235,13 +239,23 @@ func (addr IPAddress) AsUint32() uint32 {
 type MACAddress uint64
 
 func (addr MACAddress) String() string {
-	return fmt.Sprintf("%016X", uint64(addr))
+	b := make([]byte, 8)
+	binary.BigEndian.PutUint64(b, uint64(addr))
+	encoded := hex.EncodeToString(b)
+	result := ""
+	for i := 2; i < 8; i++ {
+		result += encoded[i*2 : i*2+2]
+		if i < 7 {
+			result += ":"
+		}
+	}
+	return result
 }
 
 type Error uint8
 
 func (err Error) Error() string {
-	return fmt.Sprintf("wifinina error: 0x%02X", uint8(err))
+	return "wifinina error: 0x" + hex.EncodeToString([]byte{uint8(err)})
 }
 
 // Cmd Struct Message */