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How to add and use commands in vendor class USB in transmission?

Hi!

I'm working on LPC1768 MCU.

I'm writing a program based on USBHID example delivered by Keil, and I'm trying to modify it to a Vendor specific in order to use a bulk transer, to deliver data from ADC to GUI interface.

The problem I'm actually faceing is how to make my MCU understand the commands from my GUI interface like:

const byte SWITCH_LED = 0xE0;
const byte READ_ADC   = 0xDE;

I thought that the easiest way is to scan an endpoit, to which I'm sending the command and if anything appears, scan it(the buffer) for a command. But it looks unprofessional IMHO.
In Keil example there is something much more smarter, which I don't completely understand.
They are using theese functions:

hiduser.c

uint32_t HID_GetReport (void) {

  /* ReportID = SetupPacket.wValue.WB.L; */
  switch (SetupPacket.wValue.WB.H) {
    case HID_REPORT_INPUT:
      GetInReport();
      EP0Buf[0] = InReport;
      break;
    case HID_REPORT_OUTPUT:
      return (FALSE);          /* Not Supported */
    case HID_REPORT_FEATURE:
      /* EP0Buf[] = ...; */
      /* break; */
      return (FALSE);          /* Not Supported */
  }
  return (TRUE);
}


/*
 *  HID Set Report Request Callback
 *   Called automatically on HID Set Report Request
 *    Parameters:      None (global SetupPacket and EP0Buf)
 *    Return Value:    TRUE - Success, FALSE - Error
 */

uint32_t HID_SetReport (void) {

  /* ReportID = SetupPacket.wValue.WB.L; */
  switch (SetupPacket.wValue.WB.H) {
    case HID_REPORT_INPUT:
      return (FALSE);          /* Not Supported */
    case HID_REPORT_OUTPUT:
      *OutReport = EP0Buf[0];
      SetOutReport();
      break;
    case HID_REPORT_FEATURE:
      return (FALSE);          /* Not Supported */
  }
  return (TRUE);
}

And they are calling them from

usbcore.c

#if USB_HID
              if (SetupPacket.wIndex.WB.L == USB_HID_IF_NUM) {           // IF number correct?
                switch (SetupPacket.bRequest) {
                  case HID_REQUEST_GET_REPORT:
                    if (HID_GetReport()) {
                      EP0Data.pData = EP0Buf;                            // point to data to be sent
                      USB_DataInStage();                                 // send requested data
                      goto setup_class_ok;
                    }
                    break;

Finally, the question is: Is it possible(think it is) to modify a Vendor Specific to achieve that, and where to send commands to, for instance, get to the command HID_REQUEST_GET_REPORT.

Thank You in advance for a reply, and sorry if I was unprecise.

Hope That I'm not repeating the thread. I search through the forum, but didn't find answer for how to use theese commands.