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#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <libusb-1.0/libusb.h>
#define TIMEOUT_MS 1000
#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;
}
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