First hacked-up attempt at high-speed USB bulk transfers to LPC43xx microcontroller

gistfile1.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <libusb.h>

bool read_file_to_buffer(const char* const filename, uint8_t* const buffer, uint32_t buffer_size) {
    memset(buffer, 0x69, buffer_size);
    FILE* f = fopen(filename, "rb");
    if( f == NULL ) {
        printf("fopen() failed\n");
        return false;
    }
    fread(buffer, buffer_size, 1, f);
    fclose(f);
    
    return true;
}

static float
TimevalDiff(const struct timeval *a, const struct timeval *b)
{
   return (a->tv_sec - b->tv_sec) + 1e-6f * (a->tv_usec - b->tv_usec);
}

struct timeval time_start;
uint32_t byte_count = 0;

void transfer_callback(struct libusb_transfer* transfer) {
    if( transfer->status == LIBUSB_TRANSFER_COMPLETED ) {
        byte_count += transfer->actual_length;
        libusb_submit_transfer(transfer);
    } else {
        printf("transfer status was not 'completed'\n");
    }
}

int main(int argc, char** argv) {
    if( argc != 3 ) {
        printf("Usage: usb_test <first file to transmit> <second file to transmit>\n");
        return -1;
    }

    const uint32_t buffer_size = 65536;
    
    unsigned char buffer_1[buffer_size], buffer_2[buffer_size];
    unsigned char* buffer[2] = {
        buffer_1,
        buffer_2
    };
    
    if( read_file_to_buffer(argv[1], buffer[0], buffer_size) != true ) {
        printf("Failed to read file 1\n");
        return -2;
    }

    if( read_file_to_buffer(argv[2], buffer[1], buffer_size) != true ) {
        printf("Failed to read file 2\n");
        return -3;
    }

    libusb_context* context;
    int result = libusb_init(&context);
    if( result != 0 ) {
        printf("libusb_init() failed: %d\n", result);
        return -4;
    }
    
    libusb_device_handle* device = libusb_open_device_with_vid_pid(context, 0x1fc9, 0x000c);
    if( device == NULL ) {
        printf("libusb_open_device_with_vid_pid() failed\n");
        return -5;
    }
    
    //int speed = libusb_get_device_speed(device);
    //printf("device speed: %d\n", speed);

    // TODO: Not setting configuration because it was causing
    // repeated calls on the host that would prime endpoints
    // multiple times, and confuse them (for the first transfer).
    /*
    result = libusb_set_configuration(device, 1);
    if( result != 0 ) {
        printf("libusb_set_configuration() failed: %d\n", result);
        return -6;
    }
    */
    result = libusb_claim_interface(device, 0);
    if( result != 0 ) {
        printf("libusb_claim_interface() failed: %d\n", result);
        return -7;
    }
    
    unsigned char endpoint_address = 0x02;

    const uint32_t transfer_count = 256;
    struct libusb_transfer* transfers[transfer_count];
    for(uint32_t transfer_index=0; transfer_index<transfer_count; transfer_index++) {
        transfers[transfer_index] = libusb_alloc_transfer(0);
        if( transfers[transfer_index] == 0 ) {
            printf("libusb_alloc_transfer() failed\n");
            return -6;
        }
        
        libusb_fill_bulk_transfer(
            transfers[transfer_index],
            device,
            endpoint_address,
            (unsigned char*)malloc(buffer_size),
            buffer_size,
            &transfer_callback,
            NULL,
            0
            );
        
        if( transfers[transfer_index]->buffer == 0 ) {
            printf("malloc() failed\n");
            return -7;
        }
        
        //(if( transfer_index & 2 ) {
            memcpy(transfers[transfer_index]->buffer, buffer[transfer_index & 1], buffer_size);
        //}
        
        int error = libusb_submit_transfer(transfers[transfer_index]);
        if( error != 0 ) {
            printf("libusb_submit_transfer() failed: %d\n", error);
            return -8;
        }
    }

    //////////////////////////////////////////////////////////////
    
    struct timeval timeout = { 0, 200000 };
    struct timeval time_now;

    const double progress_interval = 1.0;
    gettimeofday(&time_start, NULL);

    uint32_t call_count = 0;
    do {
        int error = libusb_handle_events_timeout(context, &timeout);
        if( error != 0 ) {
            printf("libusb_handle_events_timeout() failed: %d\n", error);
            return -10;
        }
        
        if( (call_count & 0xFF) == 0 ) {
            gettimeofday(&time_now, NULL);
            const float time_difference = TimevalDiff(&time_now, &time_start);
            if( time_difference >= progress_interval ) {
                const float rate = float(byte_count) / time_difference;
                printf("%.1f/%.3f = %.1f MiB/second\n",
                    byte_count / 1e6f,
                    time_difference,
                    rate / 1e6f
                );
                time_start = time_now;
                byte_count = 0;
            }
        }
        call_count += 1;
    } while(true);
    
    /*
    printf("transferring...\n");
    int buffer_number = 0;
    
    while(true) {
        int bytes_transferred = 0;
        unsigned int timeout = 0;
        result = libusb_bulk_transfer(
            device, endpoint_address, buffer[buffer_number],
            buffer_size, &bytes_transferred, timeout
        );
        
        if( result != 0 ) {
            printf("libusb_bulk_transfer() failed: %d\n", result);
            return -1000;
        }

        if( bytes_transferred != buffer_size ) {
            printf("libusb_bulk_transfer() failed: transferred (%d) != buffer size (%d)\n",
                bytes_transferred,
                buffer_size
            );
            return -1001;
        }

        buffer_number = 1 - buffer_number;
        
        byte_count += bytes_transferred;
        
    }
    */
    //////////////////////////////////////////////////////////////

    result = libusb_release_interface(device, 0);
    if( result != 0 ) {
        printf("libusb_release_interface() failed: %d\n", result);
        return -2000;
    }
    
    libusb_close(device);
    
    libusb_exit(context);
    
    return 0;
}

lsusb -v of Jellybean

Bus 250 Device 006: ID 1fc9:000c  
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0 
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  idVendor           0x1fc9 
  idProduct          0x000c 
  bcdDevice            0.01
  iManufacturer           0 
  iProduct                0 
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           32
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              500mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass       255 
      bInterfaceSubClass    255 
      bInterfaceProtocol    255 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x02  EP 2 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
Device Status:     0x0002
  (Bus Powered)
  Remote Wakeup Enabled