case LANG_ID:
        {
          data_to_transfer = sizeof (usb_language);
          pbuffer = &(usb_language.bLength);
          break;
        }
        case MAN_INDEX:
        {
          data_to_transfer = sizeof (usb_manufacturer);
          pbuffer = &(usb_manufacturer.bLength);
          break;
        }
        case PROD_INDEX:
        {
          data_to_transfer = sizeof (usb_product);
          pbuffer = &(usb_product.bLength);
          break;
        }
        case SN_INDEX:
        {
          data_to_transfer = sizeof (usb_serial_number);
          pbuffer = &(usb_serial_number.bLength);
          break;
        }
        default:
        {
          Usb_clear_RXSETUP();
          while (!Usb_setup_received())
          {
            Usb_set_STALLRQ();              /* send stall */
            while ((!(Usb_STALL_sent())) && (Usb_setup_received()));
            Usb_clear_STALLED();
            Usb_clear_STALLRQ();
          }
          Usb_clear_DIR();                  /* set in on EP0 */
          return;
        }
      }
      break;
    }

    default:
    {
      Usb_clear_RXSETUP();
      while (!Usb_setup_received())
      {
        Usb_set_STALLRQ();                  /* send stall */
        while ((!(Usb_STALL_sent())) && (Usb_setup_received()));
        Usb_clear_STALLED();
        Usb_clear_STALLRQ();
      }
      Usb_clear_DIR();                      /* set in on EP0 */
      return;
    }
  }

  ACC = Usb_read_byte();                    /* don't care of wIndex field */
  ACC = Usb_read_byte();
  ((Byte*)&wLength)[1] = Usb_read_byte();   /* read wLength */
  ((Byte*)&wLength)[0] = Usb_read_byte();
  if (wLength > data_to_transfer)
  {
    if ((data_to_transfer % EP_CONTROL_LENGTH) == 0)
    {
      zlp = TRUE;                           /* send a zero length packet */
    }
    else
    {
      zlp = FALSE;                          /* no need of zero length packet */
    }
  }
  else
  {
    data_to_transfer = (Byte)wLength;       /* send only requested number of data */
  }
  Usb_clear_RXSETUP() ;                     /* clear the receive setup flag */

  while (data_to_transfer > EP_CONTROL_LENGTH)
  {
    pbuffer = send_ep0_packet(pbuffer, EP_CONTROL_LENGTH);
    data_to_transfer -= EP_CONTROL_LENGTH;
    while ((!(Usb_rx_complete())) && (!(Usb_tx_complete())));
    if ((Usb_rx_complete()))                /* if no cancel from USB Host */
    {
      Usb_clear_RXOUT();
      return;
    }
    if (Usb_tx_complete())
    {
      Usb_clear_TXCMPL();
    }
  }
  /* send last data packet */
  pbuffer = send_ep0_packet(pbuffer, data_to_transfer);
  data_to_transfer = 0;
  while ((!(Usb_rx_complete())) && (!(Usb_tx_complete())));
  if ((Usb_rx_complete()))                  /* if no cancel from USB Host */
  {
    Usb_clear_RXOUT();
    return;
  }
  if (Usb_tx_complete())
  {
    Usb_clear_TXCMPL();
  }
  if (zlp == TRUE)
  {
    send_ep0_packet(pbuffer, 0);
    while ((!(Usb_rx_complete())) && (!(Usb_tx_complete())));
    if ((Usb_rx_complete()))              /* if no cancel from USB Host */
    {
      Usb_clear_RXOUT();
      return;
    }
    if (Usb_tx_complete())
    {
      Usb_clear_TXCMPL();
    }
  }
  while ((!(Usb_rx_complete())) && (!(Usb_setup_received())));
  if (Usb_setup_received())
  {
    return;
  }

  if (Usb_rx_complete())
  {
    Usb_clear_DIR();                        /* set in on EP0 */
    Usb_clear_RXOUT();
  }
}


/*F**************************************************************************
* NAME: usb_get_configuration
*----------------------------------------------------------------------------
* PARAMS:
*
* return:
*----------------------------------------------------------------------------
* PURPOSE: 
* This function manages the GET_CONFIGURATION request.
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/
void usb_get_configuration (void)
{
  Usb_clear_RXSETUP();
  Usb_set_DIR();
  if (USBCON & MSK_CONFG)
  {
    Usb_write_byte(1);
  }
  else
  {
    Usb_write_byte(0);
  }

  Usb_set_TXRDY();
  while (!(Usb_tx_complete()));
  Usb_clear_TXCMPL();
  while (!(Usb_rx_complete()));
  Usb_clear_RXOUT();
  Usb_clear_DIR();
}


/*F**************************************************************************
* NAME: usb_get_status
*----------------------------------------------------------------------------
* PARAMS:
*
* return:
*----------------------------------------------------------------------------
* PURPOSE: 
* This function manages the GET_STATUS request.
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/
void usb_get_status (void)
{
Byte wIndex;

  ACC = Usb_read_byte();                    /* dummy read */
  ACC = Usb_read_byte();                    /* dummy read */
  wIndex = Usb_read_byte();
  Usb_clear_RXSETUP();
  Usb_set_DIR();
  switch(bmRequestType) 
  {
    case REQUEST_DEVICE_STATUS:
    {
      Usb_write_byte(SELF_POWERED);
      break;
    }
    case REQUEST_INTERFACE_STATUS:
    {
      Usb_write_byte(0x00);
      break;
    }
    case REQUEST_ENDPOINT_STATUS:
    {
      wIndex = wIndex & MSK_EP_DIR;
      Usb_write_byte(endpoint_status[wIndex]);
      break;
    }
  }
  Usb_write_byte(0x00);
  Usb_set_TXRDY();
  while ((!(Usb_tx_complete())) || (Usb_setup_received()));
  Usb_clear_TXCMPL();
  while ((!(Usb_rx_complete())) || (Usb_setup_received()));
  Usb_clear_RXOUT();
  Usb_clear_DIR();
}


/*F**************************************************************************
* NAME: usb_set_feature
*----------------------------------------------------------------------------
* PARAMS:
*
* return:
*----------------------------------------------------------------------------
* PURPOSE: 
* This function manages the SET_FEATURE request.
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/
void usb_set_feature (void)
{
  if (bmRequestType == ZERO_TYPE)
  {
    Usb_clear_RXSETUP();
    Usb_set_STALLRQ();
    while (!(Usb_STALL_sent()));
    Usb_clear_STALLRQ();
  }
  if (bmRequestType == INTERFACE_TYPE)
  {
    Usb_clear_RXSETUP();
    Usb_set_STALLRQ();
    while (!(Usb_STALL_sent()));
    Usb_clear_STALLRQ();
  }
  if (bmRequestType == ENDPOINT_TYPE)
  {
    if (Usb_read_byte() == 0x00)
    {
      ACC = Usb_read_byte();                /* dummy read */
      switch (Usb_read_byte())              /* check wIndex */
      {
        case ENDPOINT_1:
        {
          Usb_select_ep(EP_IN);
          Usb_set_STALLRQ();
          Usb_select_ep(EP_CONTROL);
          endpoint_status[1] = 0x01;
          Usb_clear_RXSETUP();
          Usb_set_TXRDY();
          while (!(Usb_tx_complete()));
          Usb_clear_TXCMPL();
          break;
        }
        case ENDPOINT_2:
        {
          Usb_select_ep(EP_OUT);
          Usb_set_STALLRQ();
          Usb_select_ep(EP_CONTROL);
          endpoint_status[2] = 0x01;
          Usb_clear_RXSETUP();
          Usb_set_TXRDY();
          while (!(Usb_tx_complete()));
          Usb_clear_TXCMPL();
          break;
        }
        default:
        {
          Usb_clear_RXSETUP();
          Usb_set_STALLRQ();
          while (!(Usb_STALL_sent()));
          Usb_clear_STALLRQ();
          break;
        }
      }
    }
  }
}


/*F**************************************************************************
* NAME: usb_clear_feature
*----------------------------------------------------------------------------
* PARAMS:
*
* return:
*----------------------------------------------------------------------------
* PURPOSE: 
* This function manages the SET_FEATURE request.
*----------------------------------------------------------------------------
* EXAMPLE:
*----------------------------------------------------------------------------
* NOTE:
*----------------------------------------------------------------------------
* REQUIREMENTS: 
*****************************************************************************/
void usb_clear_feature (void)
{
  if (bmRequestType == ZERO_TYPE)
  {
    Usb_clear_RXSETUP();
    Usb_set_STALLRQ();
    while (!(Usb_STALL_sent()));
    Usb_clear_STALLRQ();
  }
  if (bmRequestType == INTERFACE_TYPE)
  {
    Usb_clear_RXSETUP();
    Usb_set_STALLRQ();
    while (!(Usb_STALL_sent()));
    Usb_clear_STALLRQ();
  }
  if (bmRequestType == ENDPOINT_TYPE)
  {
    if (Usb_read_byte() == 0x00)
    {
      ACC = Usb_read_byte();                /* dummy read */
      switch (Usb_read_byte())              /* check wIndex */
      {
        case ENDPOINT_1:
        {
          Usb_select_ep(EP_IN);
		  if(Usb_STALL_requested())
		  {
            Usb_clear_STALLRQ();
		  }
		  if(Usb_STALL_sent())
		  {
		    Usb_clear_STALLED();
          }
          UEPRST = 0x02;
          UEPRST = 0x00;
          Usb_select_ep(EP_CONTROL);
          endpoint_status[EP_IN] = 0x00;
          Usb_clear_RXSETUP();
          Usb_set_TXRDY();
          while (!(Usb_tx_complete()));
          Usb_clear_TXCMPL();
          break;
        }
        case ENDPOINT_2:
        {
          Usb_select_ep(EP_OUT);
		  if(Usb_STALL_requested())
		  {
            Usb_clear_STALLRQ();
		  }
		  if(Usb_STALL_sent())
		  {
		    Usb_clear_STALLED();
          }
		  UEPRST = 0x04;
          UEPRST = 0x00;
          Usb_select_ep(EP_CONTROL);
          endpoint_status[EP_OUT] = 0x00;
          Usb_clear_RXSETUP();
          Usb_set_TXRDY();
          while (!(Usb_tx_complete()));
          Usb_clear_TXCMPL();
          break;
        }
        case ENDPOINT_0:
        {
          Usb_clear_RXSETUP();
          Usb_set_TXRDY();
          while (!(Usb_tx_complete()));
          Usb_clear_TXCMPL();
          break;
        }
        default:
        {
          Usb_clear_RXSETUP();
          Usb_set_STALLRQ();
          while (!(Usb_STALL_sent()));
          Usb_clear_STALLRQ();
          break;
        }
      }
    }
  }
}