usb midi driver

usb_driver.cc

#include <iostream>
#include <libusb.h>
#include <cstdlib>
#include <RtMidi.h>

using namespace std;

int main() {
  RtMidiOut *midiout = 0;
  std::vector<unsigned char> message;

  // RtMidiOut constructor
  try {
    midiout = new RtMidiOut();
  }
  catch ( RtMidiError &error ) {
    error.printMessage();
    exit( EXIT_FAILURE );
  }
  midiout->openVirtualPort();
  message.push_back( 0 );
  message.push_back( 0 );
  message.push_back( 0 );
	libusb_device **devs; //pointer to pointer of device, used to retrieve a list of devices
	libusb_device_handle *dev_handle; //a device handle
	libusb_context *ctx = NULL; //a libusb session
	int r; //for return values
	ssize_t cnt; //holding number of devices in list
	r = libusb_init(&ctx); //initialize the library for the session we just declared
	if(r < 0) {
		cout<<"Init Error "<<r<<endl; //there was an error
		return 1;
	}
	libusb_set_debug(ctx, 3); //set verbosity level to 3, as suggested in the documentation

	cnt = libusb_get_device_list(ctx, &devs); //get the list of devices
	if(cnt < 0) {
		cout<<"Get Device Error"<<endl; //there was an error
		return 1;
	}
	cout<<cnt<<" Devices in list."<<endl;

	dev_handle = libusb_open_device_with_vid_pid(ctx, 0xf055, 0x0069); //these are vendorID and productID I found for my usb device
	if(dev_handle == NULL)
		cout<<"Cannot open device"<<endl;
	else
		cout<<"Device Opened"<<endl;
	libusb_free_device_list(devs, 1); //free the list, unref the devices in it

	unsigned char *data = new unsigned char[4]; //data to read

	int actual; //used to find out how many bytes were read/written
	if(libusb_kernel_driver_active(dev_handle, 0) == 1) { //find out if kernel driver is attached
		cout<<"Kernel Driver Active"<<endl;
		if(libusb_detach_kernel_driver(dev_handle, 0) == 0) //detach it
			cout<<"Kernel Driver Detached!"<<endl;
	}
	r = libusb_claim_interface(dev_handle, 1); 
	if(r < 0) {
		cout<<"Cannot Claim Interface"<<endl;
        cout << "R: " << libusb_error_name(r) << endl;
		return 1;
	}
	cout<<"Claimed Interface"<<endl;
	
    while (1) {
        r = libusb_bulk_transfer(dev_handle, (0x82 | LIBUSB_ENDPOINT_IN), data, 4, &actual, 0);
        message[0] = data[1];
        message[1] = data[2];
        message[2] = data[3];
        midiout->sendMessage( &message );
    }
	
	r = libusb_release_interface(dev_handle, 1); //release the claimed interface
	if(r!=0) {
		cout<<"Cannot Release Interface"<<endl;
		return 1;
	}
	cout<<"Released Interface"<<endl;

	libusb_close(dev_handle); //close the device we opened
	libusb_exit(ctx); //needs to be called to end the

	delete[] data; //delete the allocated memory for data
	return 0;
}