binary-format supports uf2, nrf-dfu

internal/firmware/nrfutil.go

@@ -0,0 +1,118 @@
+// From tinygo/builder/nrfutil.go
+
+package firmware
+
+import (
+	"archive/zip"
+	"bytes"
+	"encoding/binary"
+	"encoding/json"
+	"os"
+
+	"github.com/sigurn/crc16"
+)
+
+// Structure of the manifest.json file.
+type jsonManifest struct {
+	Manifest struct {
+		Application struct {
+			BinaryFile     string        `json:"bin_file"`
+			DataFile       string        `json:"dat_file"`
+			InitPacketData nrfInitPacket `json:"init_packet_data"`
+		} `json:"application"`
+		DFUVersion float64 `json:"dfu_version"` // yes, this is a JSON number, not a string
+	} `json:"manifest"`
+}
+
+// Structure of the init packet.
+// Source:
+// https://github.com/adafruit/Adafruit_nRF52_Bootloader/blob/master/lib/sdk11/components/libraries/bootloader_dfu/dfu_init.h#L47-L57
+type nrfInitPacket struct {
+	ApplicationVersion uint32   `json:"application_version"`
+	DeviceRevision     uint16   `json:"device_revision"`
+	DeviceType         uint16   `json:"device_type"`
+	FirmwareCRC16      uint16   `json:"firmware_crc16"`
+	SoftDeviceRequired []uint16 `json:"softdevice_req"` // this is actually a variable length array
+}
+
+// Create the init packet (the contents of application.dat).
+func (p nrfInitPacket) createInitPacket() []byte {
+	buf := &bytes.Buffer{}
+	binary.Write(buf, binary.LittleEndian, p.DeviceType)                      // uint16_t device_type;
+	binary.Write(buf, binary.LittleEndian, p.DeviceRevision)                  // uint16_t device_rev;
+	binary.Write(buf, binary.LittleEndian, p.ApplicationVersion)              // uint32_t app_version;
+	binary.Write(buf, binary.LittleEndian, uint16(len(p.SoftDeviceRequired))) // uint16_t softdevice_len;
+	binary.Write(buf, binary.LittleEndian, p.SoftDeviceRequired)              // uint16_t softdevice[1];
+	binary.Write(buf, binary.LittleEndian, p.FirmwareCRC16)
+	return buf.Bytes()
+}
+
+// Make a Nordic DFU firmware image from an ELF file.
+func makeDFUFirmwareImage(infile, outfile string) error {
+	// Read ELF file as input and convert it to a binary image file.
+	_, data, err := extractROM(infile)
+	if err != nil {
+		return err
+	}
+
+	// Create the zip file in memory.
+	// It won't be very large anyway.
+	buf := &bytes.Buffer{}
+	w := zip.NewWriter(buf)
+
+	// Write the application binary to the zip file.
+	binw, err := w.Create("application.bin")
+	if err != nil {
+		return err
+	}
+	_, err = binw.Write(data)
+	if err != nil {
+		return err
+	}
+
+	// Create the init packet.
+	initPacket := nrfInitPacket{
+		ApplicationVersion: 0xffff_ffff, // appears to be unused by the Adafruit bootloader
+		DeviceRevision:     0xffff,      // DFU_DEVICE_REVISION_EMPTY
+		DeviceType:         0x0052,      // ADAFRUIT_DEVICE_TYPE
+		FirmwareCRC16:      crc16.Checksum(data, crc16.MakeTable(crc16.CRC16_CCITT_FALSE)),
+		SoftDeviceRequired: []uint16{0xfffe}, // DFU_SOFTDEVICE_ANY
+	}
+
+	// Write the init packet to the zip file.
+	datw, err := w.Create("application.dat")
+	if err != nil {
+		return err
+	}
+	_, err = datw.Write(initPacket.createInitPacket())
+	if err != nil {
+		return err
+	}
+
+	// Create the JSON manifest.
+	manifest := &jsonManifest{}
+	manifest.Manifest.Application.BinaryFile = "application.bin"
+	manifest.Manifest.Application.DataFile = "application.dat"
+	manifest.Manifest.Application.InitPacketData = initPacket
+	manifest.Manifest.DFUVersion = 0.5
+
+	// Write the JSON manifest to the file.
+	jsonw, err := w.Create("manifest.json")
+	if err != nil {
+		return err
+	}
+	enc := json.NewEncoder(jsonw)
+	enc.SetIndent("", "    ")
+	err = enc.Encode(manifest)
+	if err != nil {
+		return err
+	}
+
+	// Finish the zip file.
+	err = w.Close()
+	if err != nil {
+		return err
+	}
+
+	return os.WriteFile(outfile, buf.Bytes(), 0o666)
+}