libusb之libusb_bulk_transfer之完整实例

最近研究libusb开源库，需要从下位机获取数据，下面是一个完整的例子：

#include "libusb.h"
int main(int argc, char* argv[])
{
libusb_context *usb_context = nullptr;
libusb_device **dev_list;
libusb_device *dev = NULL;
libusb_device *dev_temp;
libusb_device_handle *dev_handle = NULL;

int ret = -1;
ssize_t cnt;


if (ret = libusb_init(&usb_context) < 0)
{
printf("init error:%d\n",ret);
return ret;
}


if (cnt = libusb_get_device_list(usb_context, &dev_list) < 0)
{
printf("get device list error:%d\n", cnt);
return cnt;
}

int i = 0;
while ((dev_temp = dev_list[i++]) != NULL)
{
struct libusb_device_descriptor desc;
int r = libusb_get_device_descriptor(dev_temp, &desc);
if (r < 0) {
printf("get device descriptor error:%d");
return NULL;
}


/*printf("%x:%x (bus %d, device %d\n)",
desc.idVendor, desc.idProduct,
libusb_get_bus_number(dev_temp), libusb_get_device_address(dev_temp));*/
if ((desc.idProduct == 0xa4a0) && (desc.idVendor == 0x0525))
{
dev = dev_temp;
break;
}
}
if (dev == NULL)
{
printf("find dev error\n");
return -1;
}


ret = libusb_open(dev, &dev_handle);
if (dev_handle == NULL)
{
printf("open device error:%d\n", ret);
return ret;
}


ret = libusb_kernel_driver_active(dev_handle, 0);
if (ret == 1)
{
libusb_detach_kernel_driver(dev_handle, 0);
printf("driver error\n");
}


if (ret = libusb_claim_interface(dev_handle, 0) < 0)
{
printf("claim interface error:%d\n",ret);
libusb_free_device_list(dev_list, 1);
libusb_exit(usb_context);
return ret;
}


libusb_config_descriptor *config_descriptor_in = NULL, *config_descriptor_out = NULL;


//libusb_get_active_config_descriptor(dev, &config_descriptor);
int config = 0;
libusb_get_configuration(dev_handle, &config);


libusb_get_config_descriptor(dev, 0, &config_descriptor_in);
libusb_get_config_descriptor(dev, 1, &config_descriptor_out);
if (config_descriptor_in)
{
unsigned char data[4096] = "aaaaaffff";
unsigned char data_rec[4096] = "\0";
int length = 0;
//ret = libusb_bulk_transfer(dev_handle, config_descriptor_in->interface->altsetting->endpoint->bEndpointAddress, data, 9, &length, 0);
ret = libusb_bulk_transfer(dev_handle, 1, data, 4096, &length, 0);//host--------------->device
if (ret < 0)
printf("bulk transfer error\n");
else
{
for (int i = 0; i < 100000; i++)
{
memset(data_rec, 0, 4096);
ret = libusb_bulk_transfer(dev_handle, 129, data_rec, 4096, &length, 0);//device--------->host
printf("i = %d,receive data：%s",i, data_rec);
}
}
} 
else 
printf("get config_descriptor error\n");
libusb_free_device_list(dev_list,1);
libusb_exit(usb_context);
return 0;
}