Async and sync bulk read with libusb

libusb_bulk_read.c

#include "libusb-1.0/libusb.h"
#include <stdio.h>
#include <iostream>
#include <ctime>

static const int USB_VID = 0x0547;
static const int USB_PID = 0x1002;
static const int USB_EP_WRITE = 0x01;
static const int USB_EP_READ = 0x81;
static int r = 0;
static libusb_device_handle* dev = NULL;
static struct libusb_transfer* transferIn = NULL;

static int ERROR_LIBUSB_NO_ERROR = 0;
static int ERROR_LIBUSB_ERROR = -1;

static clock_t T1 = 0;
static clock_t T2 = 0;
static uint32_t packetLen = 0;
static uint32_t packetCount = 0;

static int CloseDevice(libusb_device_handle* handle)
{
	if (dev != NULL) {
		libusb_close(dev);
		dev = NULL;
	}
	return ERROR_LIBUSB_NO_ERROR;
}

static int OpenDevice(int vid, int pid)
{
	dev = libusb_open_device_with_vid_pid(NULL, vid, pid);
	if (dev == NULL) {
		fprintf(stderr, "Open device failed\n");
		return ERROR_LIBUSB_ERROR;
	}
	else {
		if (libusb_kernel_driver_active(dev, 0) == 1)
		{
			//fprintf(stderr, "Kernel Driver Active\n");
			if (libusb_detach_kernel_driver(dev, 0) != 0)
			{
				fprintf(stderr, "Couldn't detach kernel driver!\n");
				CloseDevice(dev);
				return ERROR_LIBUSB_ERROR;
			}
		}

		r = libusb_claim_interface(dev, 0);
		if (r < 0)
		{
			fprintf(stderr, "Cannot Claim Interface\n");
			CloseDevice(dev);
			return ERROR_LIBUSB_ERROR;
		}
		return ERROR_LIBUSB_NO_ERROR;
	}
}


static int SyncRead()
{
	uint32_t buffer[128];
	int nRead = 0;
	while (true) {
		uint32_t start = clock();
		int nRet = libusb_bulk_transfer(dev, 0x81, reinterpret_cast<uint8_t*>(buffer), 128 * sizeof(uint32_t), &nRead, 500);
		if (nRet == 0) {
			uint32_t end = clock();
			std::cout << "Cmd:" << buffer[0] << "\tPacket Id:" << buffer[2] << "\tRead count:" << nRead << "\t Used:" << (end - start) << " ms" << std::endl;
		}
	}
	return 0;
}

void DataReceivedCallback(struct libusb_transfer* transfer)
{
	T2 = clock();
	libusb_submit_transfer(transferIn);
	uint32_t* buffer = reinterpret_cast<uint32_t*>(transfer->buffer);
	std::cout << "Cmd:" << buffer[0] << "\tPacket Id:" << buffer[2] << "\tRead count:" << transfer->actual_length << "\t Used:" << (T2 - T1) << " ms" << std::endl;
	T1 = T2;
}

static int AsyncRead()
{
	transferIn = libusb_alloc_transfer(0);
	uint32_t buffer[128 * 64];
	libusb_fill_bulk_transfer(transferIn, dev, 0x81, reinterpret_cast<uint8_t*>(buffer), 128 * sizeof(uint32_t) * 64, DataReceivedCallback, NULL, 500);
	r = libusb_submit_transfer(transferIn);
	while (1) {
		r = libusb_handle_events_completed(NULL, NULL);
		if (r < 0) {
			break;
		}
	}
	return 0;
}

int main()
{

	r = libusb_init(/*ctx=*/NULL);
	int ret = OpenDevice(USB_VID, USB_PID);
	//SyncRead();
	AsyncRead();
	CloseDevice(dev);
	libusb_exit(NULL);
	return 0;
}