Add support for the ESP8266

Makefile

@@ -356,6 +356,9 @@ ifneq ($(AVR), 0)
 endif
 ifneq ($(XTENSA), 0)
 	$(TINYGO) build -size short -o test.bin -target=esp32-wroom-32      examples/blinky1
+	@$(MD5SUM) test.bin
+	$(TINYGO) build -size short -o test.bin -target=nodemcu             examples/blinky1
+	@$(MD5SUM) test.bin
 endif
 	$(TINYGO) build -size short -o test.hex -target=hifive1b            examples/blinky1
 	@$(MD5SUM) test.hex

builder/build.go

@@ -292,10 +292,11 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 			if err != nil {
 				return err
 			}
-		case "esp32":
-			// Special format for the ESP32 chip (parsed by the ROM bootloader).
+		case "esp32", "esp8266":
+			// Special format for the ESP family of chips (parsed by the ROM
+			// bootloader).
 			tmppath = filepath.Join(dir, "main"+outext)
-			err := makeESP32FirmareImage(executable, tmppath)
+			err := makeESPFirmareImage(executable, tmppath, outputBinaryFormat)
 			if err != nil {
 				return err
 			}

builder/esp.go

@@ -22,15 +22,15 @@ type espImageSegment struct {
 	data []byte
 }
 
-// makeESP32Firmare converts an input ELF file to an image file for the ESP32
-// chip. This is a special purpose image format just for the ESP32 chip, and is
-// parsed by the on-chip mask ROM bootloader.
+// makeESPFirmare converts an input ELF file to an image file for an ESP32 or
+// ESP8266 chip. This is a special purpose image format just for the ESP chip
+// family, and is parsed by the on-chip mask ROM bootloader.
 //
 // The following documentation has been used:
 // https://github.com/espressif/esptool/wiki/Firmware-Image-Format
 // https://github.com/espressif/esp-idf/blob/8fbb63c2a701c22ccf4ce249f43aded73e134a34/components/bootloader_support/include/esp_image_format.h#L58
 // https://github.com/espressif/esptool/blob/master/esptool.py
-func makeESP32FirmareImage(infile, outfile string) error {
+func makeESPFirmareImage(infile, outfile, format string) error {
 	inf, err := elf.Open(infile)
 	if err != nil {
 		return err
@@ -79,26 +79,49 @@ func makeESP32FirmareImage(infile, outfile string) error {
 	outf := &bytes.Buffer{}
 
 	// Image header.
-	// Details: https://github.com/espressif/esp-idf/blob/8fbb63c2/components/bootloader_support/include/esp_image_format.h#L58
-	binary.Write(outf, binary.LittleEndian, struct {
-		magic          uint8
-		segment_count  uint8
-		spi_mode       uint8
-		spi_speed_size uint8
-		entry_addr     uint32
-		wp_pin         uint8
-		spi_pin_drv    [3]uint8
-		reserved       [11]uint8
-		hash_appended  bool
-	}{
-		magic:          0xE9,
-		segment_count:  byte(len(segments)),
-		spi_mode:       0, // irrelevant, replaced by esptool when flashing
-		spi_speed_size: 0, // spi_speed, spi_size: replaced by esptool when flashing
-		entry_addr:     uint32(inf.Entry),
-		wp_pin:         0xEE, // disable WP pin
-		hash_appended:  true, // add a SHA256 hash
-	})
+	switch format {
+	case "esp32":
+		// Header format:
+		// https://github.com/espressif/esp-idf/blob/8fbb63c2/components/bootloader_support/include/esp_image_format.h#L58
+		binary.Write(outf, binary.LittleEndian, struct {
+			magic          uint8
+			segment_count  uint8
+			spi_mode       uint8
+			spi_speed_size uint8
+			entry_addr     uint32
+			wp_pin         uint8
+			spi_pin_drv    [3]uint8
+			reserved       [11]uint8
+			hash_appended  bool
+		}{
+			magic:          0xE9,
+			segment_count:  byte(len(segments)),
+			spi_mode:       0, // irrelevant, replaced by esptool when flashing
+			spi_speed_size: 0, // spi_speed, spi_size: replaced by esptool when flashing
+			entry_addr:     uint32(inf.Entry),
+			wp_pin:         0xEE, // disable WP pin
+			hash_appended:  true, // add a SHA256 hash
+		})
+	case "esp8266":
+		// Header format:
+		// https://github.com/espressif/esptool/wiki/Firmware-Image-Format
+		// Basically a truncated version of the ESP32 header.
+		binary.Write(outf, binary.LittleEndian, struct {
+			magic          uint8
+			segment_count  uint8
+			spi_mode       uint8
+			spi_speed_size uint8
+			entry_addr     uint32
+		}{
+			magic:          0xE9,
+			segment_count:  byte(len(segments)),
+			spi_mode:       0,    // irrelevant, replaced by esptool when flashing
+			spi_speed_size: 0x20, // spi_speed, spi_size: replaced by esptool when flashing
+			entry_addr:     uint32(inf.Entry),
+		})
+	default:
+		return fmt.Errorf("builder: unknown binary format %#v, expected esp32 or esp8266", format)
+	}
 
 	// Write all segments to the image.
 	// https://github.com/espressif/esptool/wiki/Firmware-Image-Format#segment
@@ -119,9 +142,11 @@ func makeESP32FirmareImage(infile, outfile string) error {
 	outf.Write(make([]byte, 15-outf.Len()%16))
 	outf.WriteByte(checksum)
 
-	// SHA256 hash (to protect against image corruption, not for security).
-	hash := sha256.Sum256(outf.Bytes())
-	outf.Write(hash[:])
+	if format == "esp32" {
+		// SHA256 hash (to protect against image corruption, not for security).
+		hash := sha256.Sum256(outf.Bytes())
+		outf.Write(hash[:])
+	}
 
 	// Write the image to the output file.
 	return ioutil.WriteFile(outfile, outf.Bytes(), 0666)

src/device/esp/esp8266.S

@@ -0,0 +1,6 @@
+
+.section .text.tinygo_scanCurrentStack
+.global tinygo_scanCurrentStack
+tinygo_scanCurrentStack:
+    // TODO: save callee saved registers on the stack
+    j tinygo_scanstack

src/machine/board_nodemcu.go

@@ -0,0 +1,21 @@
+// +build nodemcu
+
+// Pinout for the NodeMCU dev kit.
+
+package machine
+
+// GPIO pins on the NodeMCU board.
+const (
+	D0 Pin = 16
+	D1 Pin = 5
+	D2 Pin = 4
+	D3 Pin = 0
+	D4 Pin = 2
+	D5 Pin = 14
+	D6 Pin = 12
+	D7 Pin = 13
+	D8 Pin = 15
+)
+
+// Onboard blue LED (on the AI-Thinker module).
+const LED = D4

src/machine/machine_esp8266.go

@@ -0,0 +1,159 @@
+// +build esp8266
+
+package machine
+
+import (
+	"device/esp"
+	"runtime/volatile"
+)
+
+func CPUFrequency() uint32 {
+	return 80000000 // 80MHz
+}
+
+type PinMode uint8
+
+const (
+	PinOutput PinMode = iota
+	PinInput
+)
+
+// Pins that are fixed by the chip.
+const (
+	UART_TX_PIN Pin = 1
+	UART_RX_PIN Pin = 3
+)
+
+// Pin functions are not trivial. The below array maps a pin number (GPIO
+// number) to the pad as used in the IO mux.
+// Tables with the mapping:
+// https://www.esp8266.com/wiki/doku.php?id=esp8266_gpio_pin_allocations#pin_functions
+// https://www.espressif.com/sites/default/files/documentation/ESP8266_Pin_List_0.xls
+var pinPadMapping = [...]uint8{
+	12: 0,
+	13: 1,
+	14: 2,
+	15: 3,
+	3:  4,
+	1:  5,
+	6:  6,
+	7:  7,
+	8:  8,
+	9:  9,
+	10: 10,
+	11: 11,
+	0:  12,
+	2:  13,
+	4:  14,
+	5:  15,
+}
+
+// getPad returns the pad number and the register to configure this pad.
+func (p Pin) getPad() (uint8, *volatile.Register32) {
+	pad := pinPadMapping[p]
+	var reg *volatile.Register32
+	switch pad {
+	case 0:
+		reg = &esp.IO_MUX.IO_MUX_MTDI
+	case 1:
+		reg = &esp.IO_MUX.IO_MUX_MTCK
+	case 2:
+		reg = &esp.IO_MUX.IO_MUX_MTMS
+	case 3:
+		reg = &esp.IO_MUX.IO_MUX_MTDO
+	case 4:
+		reg = &esp.IO_MUX.IO_MUX_U0RXD
+	case 5:
+		reg = &esp.IO_MUX.IO_MUX_U0TXD
+	case 6:
+		reg = &esp.IO_MUX.IO_MUX_SD_CLK
+	case 7:
+		reg = &esp.IO_MUX.IO_MUX_SD_DATA0
+	case 8:
+		reg = &esp.IO_MUX.IO_MUX_SD_DATA1
+	case 9:
+		reg = &esp.IO_MUX.IO_MUX_SD_DATA2
+	case 10:
+		reg = &esp.IO_MUX.IO_MUX_SD_DATA3
+	case 11:
+		reg = &esp.IO_MUX.IO_MUX_SD_CMD
+	case 12:
+		reg = &esp.IO_MUX.IO_MUX_GPIO0
+	case 13:
+		reg = &esp.IO_MUX.IO_MUX_GPIO2
+	case 14:
+		reg = &esp.IO_MUX.IO_MUX_GPIO4
+	case 15:
+		reg = &esp.IO_MUX.IO_MUX_GPIO5
+	}
+	return pad, reg
+}
+
+// Configure sets the given pin as output or input pin.
+func (p Pin) Configure(config PinConfig) {
+	switch config.Mode {
+	case PinInput, PinOutput:
+		pad, reg := p.getPad()
+		if pad >= 12 { // pin 0, 2, 4, 5
+			reg.Set(0 << 4) // function 0 at bit position 4
+		} else {
+			reg.Set(3 << 4) // function 3 at bit position 4
+		}
+		if config.Mode == PinOutput {
+			esp.GPIO.GPIO_ENABLE_W1TS.Set(1 << p)
+		} else {
+			esp.GPIO.GPIO_ENABLE_W1TC.Set(1 << p)
+		}
+	}
+}
+
+// Set sets the output value of this pin to high (true) or low (false).
+func (p Pin) Set(value bool) {
+	if value {
+		esp.GPIO.GPIO_OUT_W1TS.Set(1 << p)
+	} else {
+		esp.GPIO.GPIO_OUT_W1TC.Set(1 << p)
+	}
+}
+
+// Return the register and mask to enable a given GPIO pin. This can be used to
+// implement bit-banged drivers.
+//
+// Warning: only use this on an output pin!
+func (p Pin) PortMaskSet() (*uint32, uint32) {
+	return &esp.GPIO.GPIO_OUT_W1TS.Reg, 1 << p
+}
+
+// Return the register and mask to disable a given GPIO pin. This can be used to
+// implement bit-banged drivers.
+//
+// Warning: only use this on an output pin!
+func (p Pin) PortMaskClear() (*uint32, uint32) {
+	return &esp.GPIO.GPIO_OUT_W1TC.Reg, 1 << p
+}
+
+// UART0 is a hardware UART that supports both TX and RX.
+var UART0 = UART{Buffer: NewRingBuffer()}
+
+type UART struct {
+	Buffer *RingBuffer
+}
+
+// Configure the UART baud rate. TX and RX pins are fixed by the hardware so
+// cannot be modified and will be ignored.
+func (uart UART) Configure(config UARTConfig) {
+	if config.BaudRate == 0 {
+		config.BaudRate = 115200
+	}
+	esp.UART0.UART_CLKDIV.Set(CPUFrequency() / config.BaudRate)
+}
+
+// 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 {
+	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
+}