usbcom go rewrite

5 files changed, 262 insertions, 194 deletions

diff --git a/sw/usbcom/go.mod b/sw/usbcom/go.mod
new file mode 100644
index 0000000..1870f76
--- /dev/null
+++ b/sw/usbcom/go.mod
@@ -0,0 +1,8 @@
+module git.samanthony.xyz/can_gauge_interface/sw/usbcom
+
+go 1.24.6
+
+require (
+	github.com/google/gousb v1.1.3 // indirect
+	golang.org/x/sync v0.17.0 // indirect
+)
diff --git a/sw/usbcom/go.sum b/sw/usbcom/go.sum
new file mode 100644
index 0000000..64a2dc3
--- /dev/null
+++ b/sw/usbcom/go.sum
@@ -0,0 +1,8 @@
+github.com/google/gousb v1.1.3 h1:xt6M5TDsGSZ+rlomz5Si5Hmd/Fvbmo2YCJHN+yGaK4o=
+github.com/google/gousb v1.1.3/go.mod h1:GGWUkK0gAXDzxhwrzetW592aOmkkqSGcj5KLEgmCVUg=
+github.com/gotmc/libusb/v2 v2.3.4 h1:xDKi52trBIq7QTMxlhHy9zgb+HRmimSBo8yhx+k1NWU=
+github.com/gotmc/libusb/v2 v2.3.4/go.mod h1:rU0mvps+snf/CHvEkISbxrwUlWpt6VluOkjqpKo6TFw=
+github.com/sam-rba/share v0.3.0 h1:aBVvgSbcBaH43Jrbq++iz15/DAso/D6oJDm+dDM4E40=
+github.com/sam-rba/share v0.3.0/go.mod h1:rDx/wFG1Vc6JO1F/F0eBnkcy2wHwV0T9100ig/hu12A=
+golang.org/x/sync v0.17.0 h1:l60nONMj9l5drqw6jlhIELNv9I0A4OFgRsG9k2oT9Ug=
+golang.org/x/sync v0.17.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
diff --git a/sw/usbcom/main.go b/sw/usbcom/main.go
new file mode 100644
index 0000000..70661d9
--- /dev/null
+++ b/sw/usbcom/main.go
@@ -0,0 +1,85 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os"
+
+	"golang.org/x/sync/errgroup"
+
+	"git.samanthony.xyz/can_gauge_interface/sw/usbcom/usb"
+)
+
+const bufSize = 512
+
+func main() {
+	exitCode := make(chan int)
+	go exit(exitCode)
+	defer close(exitCode)
+
+	dev, err := usb.Connect()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error connecting to device: %v\n", err)
+		exitCode <- 1
+		return
+	}
+	defer func() {
+		if err := dev.Close(); err != nil {
+			fmt.Fprintf(os.Stderr, "Error :%v\n", err)
+			exitCode <- 1
+		}
+	}()
+
+	var group errgroup.Group
+	ctx, cancel := context.WithCancel(context.Background())
+
+	// Host->Device
+	group.Go(func() error {
+		err := hostToDevice(dev)
+		cancel() // device->host routine
+		return err
+	})
+
+	// Device->Host
+	group.Go(func() error {
+		return deviceToHost(ctx, dev)
+	})
+
+	if err = group.Wait(); err != nil {
+		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+		exitCode <- 1
+	}
+}
+
+func exit(code <-chan int) {
+	worst := 0
+	for c := range code {
+		if c > worst {
+			worst = c
+		}
+	}
+	os.Exit(worst)
+}
+
+func hostToDevice(dev *usb.Device) error {
+	_, err := io.Copy(dev, os.Stdin)
+	return err
+}
+
+func deviceToHost(ctx context.Context, dev *usb.Device) error {
+	buf := make([]byte, bufSize)
+	for {
+		select {
+		case <-ctx.Done():
+			return nil
+		default:
+		}
+
+		n, err := dev.Read(buf)
+		if err != nil {
+			return err
+		}
+		fmt.Print(string(buf[:n]))
+	}
+}
diff --git a/sw/usbcom/usb/usb.go b/sw/usbcom/usb/usb.go
new file mode 100644
index 0000000..1fecf4a
--- /dev/null
+++ b/sw/usbcom/usb/usb.go
@@ -0,0 +1,161 @@
+package usb
+
+import (
+	"fmt"
+
+	"github.com/google/gousb"
+)
+
+const (
+	vendorId  gousb.ID = 0x04d8
+	productId gousb.ID = 0x000a
+
+	inEndpointAddr  = 0x82
+	outEndpointAddr = 0x02
+)
+
+type Device struct {
+	ctx       *gousb.Context
+	dev       *gousb.Device
+	closeIntf func()
+	in        *gousb.ReadStream  // IN endpoint (device->host)
+	out       *gousb.WriteStream // OUT endpoint (host->device)
+}
+
+func Connect() (*Device, error) {
+	ctx := gousb.NewContext()
+
+	dev, err := ctx.OpenDeviceWithVIDPID(vendorId, productId)
+	if err != nil {
+		ctx.Close()
+		return nil, err
+	}
+
+	intf, closeIntf, err := interfaceByClass(dev, gousb.ClassData)
+	if err != nil {
+		dev.Close()
+		ctx.Close()
+		return nil, err
+	}
+
+	inEp, err := intf.InEndpoint(inEndpointAddr)
+	if err != nil {
+		closeIntf()
+		dev.Close()
+		ctx.Close()
+		return nil, err
+	}
+
+	inEpDesc, ok := intf.Setting.Endpoints[inEndpointAddr]
+	if !ok {
+		closeIntf()
+		dev.Close()
+		ctx.Close()
+		return nil, fmt.Errorf("no such endpoint: %x", inEndpointAddr)
+	}
+
+	in, err := inEp.NewStream(inEpDesc.MaxPacketSize, 1)
+	if err != nil {
+		closeIntf()
+		dev.Close()
+		ctx.Close()
+		return nil, err
+	}
+
+	outEp, err := intf.OutEndpoint(outEndpointAddr)
+	if err != nil {
+		closeIntf()
+		dev.Close()
+		ctx.Close()
+		return nil, err
+	}
+
+	outEpDesc, ok := intf.Setting.Endpoints[outEndpointAddr]
+	if !ok {
+		closeIntf()
+		dev.Close()
+		ctx.Close()
+		return nil, fmt.Errorf("no such endpoint: %x", outEndpointAddr)
+	}
+
+	out, err := outEp.NewStream(outEpDesc.MaxPacketSize, 1)
+	if err != nil {
+		closeIntf()
+		dev.Close()
+		ctx.Close()
+		return nil, err
+	}
+
+	return &Device{
+		ctx,
+		dev,
+		closeIntf,
+		in, out,
+	}, nil
+}
+
+func interfaceByClass(dev *gousb.Device, class gousb.Class) (intf *gousb.Interface, close func(), err error) {
+	cfgNum, err := dev.ActiveConfigNum()
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to get active config number of device %s: %v", dev, err)
+	}
+	cfg, err := dev.Config(cfgNum)
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to claim config %d of device %s: %v", cfgNum, dev, err)
+	}
+
+	intfNum, altNum, ok := func() (int, int, bool) {
+		for i, intf := range cfg.Desc.Interfaces {
+			for a, alt := range intf.AltSettings {
+				if alt.Class == class {
+					return i, a, true
+				}
+			}
+		}
+		return -1, -1, false
+	}()
+	if !ok {
+		cfg.Close()
+		return nil, nil, fmt.Errorf("failed to get %s interface of device %s: %v", class, dev, err)
+	}
+
+	intf, err = cfg.Interface(intfNum, altNum)
+	if err != nil {
+		cfg.Close()
+		return nil, nil, fmt.Errorf("failed to select interface (%d,%d) of config %d of device %s: %v", intfNum, altNum, cfgNum, dev, err)
+	}
+
+	return intf, func() {
+		intf.Close()
+		cfg.Close()
+	}, nil
+}
+
+func (dev *Device) Close() error {
+	outErr := dev.out.Close()
+	inErr := dev.in.Close()
+	dev.closeIntf()
+	devErr := dev.dev.Close()
+	ctxErr := dev.ctx.Close()
+
+	return nonNil(outErr, inErr, devErr, ctxErr)
+}
+
+func nonNil(errs ...error) error {
+	for _, err := range errs {
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Read from the IN endpoint (device->host)
+func (dev *Device) Read(p []byte) (n int, err error) {
+	return dev.in.Read(p)
+}
+
+// Write to the OUT endpoint (host->device)
+func (dev *Device) Write(p []byte) (n int, err error) {
+	return dev.out.Write(p)
+}
diff --git a/sw/usbcom/usbcom.c b/sw/usbcom/usbcom.c
deleted file mode 100644
index a374875..0000000
--- a/sw/usbcom/usbcom.c
+++ /dev/null
@@ -1,194 +0,0 @@
-#include <assert.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-
-#include <libusb-1.0/libusb.h>
-
-#define TIMEOUT_MS 5000
-
-#define BUF_SIZE 512
-
-#define INTERFACE 0
-
-enum {
-	VENDOR_ID = 0x04d8,
-	PRODUCT_ID = 0x000a,
-};
-
-enum {
-	SET_LINE_CODING = 0x20,
-	SET_CONTROL_LINE_STATE = 0x22,
-};
-
-enum {
-	ACM_CTRL_DTR = 0x01,
-	ACM_CTRL_RTS = 0x02,
-};
-
-enum {
-	EP_OUT_ADDR = 0x02,
-	EP_IN_ADDR = 0x82,
-};
-
-// line encoding: 9600 8N1
-// 9600 = 0x2580 LE
-static unsigned char encoding[] = {0x80, 0x25, 0x00, 0x00, 0x00, 0x00, 0x08};
-
-// Returns NULL on error
-static libusb_device_handle *
-setup(void) {
-	int res;
-	libusb_device_handle *devh;
-
-	res = libusb_init_context(NULL, NULL, 0);
-	if (res < 0) {
-		fprintf(stderr, "Error initializing libusb: %s\n", libusb_strerror(res));
-		return NULL;
-	}
-
-	devh = libusb_open_device_with_vid_pid(NULL, VENDOR_ID, PRODUCT_ID);
-	if (!devh) {
-		fprintf(stderr, "Error finding USB device\n");
-		return NULL;
-	}
-
-	res = libusb_claim_interface(devh, INTERFACE);
-	if (res < 0) {
-		fprintf(stderr, "Failed to claim interface: %s\n", libusb_strerror(res));
-		libusb_close(devh);
-		return NULL;
-	}
-
-	res = libusb_control_transfer(devh, 0x21, SET_CONTROL_LINE_STATE, ACM_CTRL_DTR | ACM_CTRL_RTS, 0, NULL, 0, TIMEOUT_MS);
-	if (res < 0) {
-		fprintf(stderr, "Error during control transfer: %s\n", libusb_strerror(res));
-		libusb_close(devh);
-		return NULL;
-	}
-
-	res = libusb_control_transfer(devh, 0x21, SET_LINE_CODING, 0, 0, encoding, sizeof(encoding), TIMEOUT_MS);
-	if (res < 0) {
-		fprintf(stderr, "Error during control transfer: %s\n", libusb_strerror(res));
-		libusb_close(devh);
-		return NULL;
-	}
-
-	return devh;
-}
-
-static void
-teardown(libusb_device_handle *devh) {
-	libusb_release_interface(devh, INTERFACE);
-	libusb_close(devh);
-	libusb_exit(NULL);
-}
-
-// Send bytes to USB
-static void
-txChars(libusb_device_handle *devh, unsigned char *data, int n) {
-	int actualLen, res;
-
-	actualLen = 0;
-	while (actualLen < n) {
-		res = libusb_bulk_transfer(devh, EP_OUT_ADDR, data, n, &actualLen, TIMEOUT_MS);
-		if (res == LIBUSB_ERROR_TIMEOUT) {
-			printf("Tx timeout (%d)\n", actualLen);
-		} else if (res < 0) {
-			fprintf(stderr, "Tx error: %s\n", libusb_strerror(res));
-		}
-		assert(actualLen <= n);
-		n -= actualLen;
-		data += actualLen;
-	}
-}
-
-// Read data from USB
-// Returns number of bytes read, or -1 on error
-static int
-rxChars(libusb_device_handle *devh, unsigned char *data, int size) {
-	int res, len;
-
-	res = libusb_bulk_transfer(devh, EP_IN_ADDR, data, size, &len, TIMEOUT_MS);
-	if (res == LIBUSB_ERROR_TIMEOUT) {
-		fprintf(stderr, "Rx timeout\n");
-		return -1;
-	} else if (res < 0) {
-		fprintf(stderr, "Rx error: %s\n", libusb_strerror(res));
-		return -1;
-	}
-	return len;
-}
-
-// Get line from stdin
-// Includes '\n'
-// Returns number of chars prior to NUL, or EOF on end of file or error
-static int
-scanline(char *buf, size_t size) {
-	int c, n;
-
-	c = '\0';
-	n = 0;
-	while (n+1 < size) {
-		c = getchar();
-		if (c == EOF) {
-			break;
-		}
-		buf[n++] = c;
-		if (c == '\n') {
-			break;
-		}
-	}
-
-	if (size > 0) {
-		buf[n] = '\0';
-	}
-
-	return ((c == EOF) && (n < 1)) ? EOF : n;
-}
-
-static void
-sendCommand(libusb_device_handle *devh) {
-	unsigned char buf[BUF_SIZE];
-	int len;
-
-	while ((len = scanline(buf, sizeof(buf))) != EOF) {
-		txChars(devh, buf, len);
-		if (len > 0 && buf[len-1] == '\n') {
-			break;
-		}
-	}
-}
-
-static void
-printResponse(libusb_device_handle *devh) {
-	unsigned char buf[BUF_SIZE];
-	int len;
-
-	while ((len = rxChars(devh, buf, sizeof(buf)-1)) >= 0) {
-		buf[len] = '\0';
-		printf("%s", buf);
-		if (len > 0 && buf[len-1] == '\n') {
-			return;
-		}
-	}
-}
-
-int
-main(int argc, char *argv[]) {
-	libusb_device_handle *devh;
-
-	devh = setup();
-	if (!devh) {
-		return 1;
-	}
-
-	for (;;) {
-		sendCommand(devh);
-		printResponse(devh);
-	}
-
-	teardown(devh);
-	return 0;
-}