#include <unistd.h>
#include <stdint.h>
#include <stdio.h>
#include <libusb-1.0/libusb.h>

static void print_devs(libusb_device **devs)  
{  
    libusb_device *dev;  
    int i = 0;  
  
    while ((dev = devs[i++]) != NULL) {  
        struct libusb_device_descriptor desc;  
        int r = libusb_get_device_descriptor(dev, &desc);  
        if (r < 0) {  
            fprintf(stderr, "failed to get device descriptor");  
            return;  
        }  
  
        printf("%04x:%04x (bus %d, device %d)\n",  
            desc.idVendor, desc.idProduct,  
            libusb_get_bus_number(dev), libusb_get_device_address(dev));  
    }  
}  

int main()
{
	int r;
	ssize_t cnt;
	libusb_device_handle *dev_handle;             //a device handle
	libusb_device **devs;                         //devices
	//libusb_context **ctx=NULL;	
	r=libusb_init(NULL);                          //init 初始化libusb
        if(r<0) {
            printf("failed to init libusb\n");
            return 1;
        }
	cnt = libusb_get_device_list(NULL,&devs);      //获取设备列表
        if (cnt < 0) {
            printf("failed to get device list\n");  
            return 1;
        }
	//print_devs(devs);
        dev_handle = libusb_open_device_with_vid_pid(NULL, 0x2833, 0x0002); 
	if(dev_handle == NULL){
		printf("Cannot open device\n");
		return 1;
	}else
		printf("Device Opened\n");

	libusb_free_device_list(devs, 1);             //free the list, unref the devices in it
	
	if(libusb_kernel_driver_active(dev_handle, 0) == 1) { //find out if kernel driver is attached
		printf("Kernel Driver Active\n");
		if(libusb_detach_kernel_driver(dev_handle, 0) == 0) //detach it
			printf("Kernel Driver Detached!\n");
	}
	r = libusb_claim_interface(dev_handle, 0);         //claim interface 0 (the first) of device (mine had jsut 1)
	if(r < 0) {
		printf("Cannot Claim Interface\n");
		return 1;
	}
	printf("Claimed Interface\n");
	sleep(1);	
	unsigned char data[2];

	unsigned char tmp_char[64];
	data[0]=0x02;data[1]=0x64;
	int transferred;
	int actual; //used to find out how many bytes were written
	while(1){
		//r = libusb_interrupt_transfer(dev_handle, (0x01 | LIBUSB_ENDPOINT_OUT), data, 2, &actual, 0); //my device's out endpoint was 1, found with trial- the device had 2 endpoints: 2 and 129
		//if(r == 0 && actual == 2) //we wrote the 2 bytes successfully
			//printf("Writing Successful\n");
		//else
		//	printf("Write Error\n");
	
		//r = libusb_interrupt_transfer(dev_handle, (0x01 | LIBUSB_ENDPOINT_IN),tmp_char,64,&actual, 1000);//pay attion
		
		r = libusb_bulk_transfer(dev_handle, (0x01 | LIBUSB_ENDPOINT_IN), tmp_char, 64, &transferred,1000);
		if(r == 0 && actual == 64) //we read the 64 bytes successfully
			printf("Read Successful\n");
		else
			printf("Read Error\n");
		printf("%i,%i\n",r,actual);

		int16_t mx = *(int16_t *)(tmp_char+56);
		int16_t my = *(int16_t *)(tmp_char+58);
		int16_t mz = *(int16_t *)(tmp_char+60);
		printf("mag:%d,%d,%d\n",mx,my,mz);
		usleep(1000*500);		
		//printf("%s","\033[1H\033[2J");//clear display
		
	}	
	
	r = libusb_release_interface(dev_handle, 0); //release the claimed interface
	if(r!=0) {
		printf("Cannot Release Interface\n");
		return 1;
	}
	printf("Released Interface\n");

	libusb_close(dev_handle);                    //close the device we opened
	libusb_exit(NULL);                            //needs to be called to end the
	
	return 0;
}