uint AT91F_UDP_Read(AT91PS_CDC pCdc, char *pData, uint length)
{
AT91PS_UDP pUdp = pCdc->pUdp;
uint packetSize, nbBytesRcv = 0, currentReceiveBank = pCdc->currentRcvBank;
if ((pUdp->UDP_CSR[AT91C_EP_OUT] & AT91C_UDP_RX_DATA_BK0)||(pUdp->UDP_CSR[AT91C_EP_OUT] & AT91C_UDP_RX_DATA_BK1))
{
  return 0;//то есть, если не было ни одного пакета принято, то просто выходим
}
while (length) {
  if ( !AT91F_UDP_IsConfigured(pCdc) )
   break;
  if ( pUdp->UDP_CSR[AT91C_EP_OUT] & currentReceiveBank ) {
   packetSize = MIN(pUdp->UDP_CSR[AT91C_EP_OUT] >> 16, length);
   length -= packetSize;
   if (packetSize < AT91C_EP_OUT_SIZE)
    length = 0;
   while(packetSize--)
    pData[nbBytesRcv++] = pUdp->UDP_FDR[AT91C_EP_OUT];
   pUdp->UDP_CSR[AT91C_EP_OUT] &= ~(currentReceiveBank);
   if (currentReceiveBank == AT91C_UDP_RX_DATA_BK0)
    currentReceiveBank = AT91C_UDP_RX_DATA_BK1;
   else
    currentReceiveBank = AT91C_UDP_RX_DATA_BK0;</P> <P>  }
}
        pUdp->UDP_CSR[AT91C_EP_OUT] &= ~(AT91C_UDP_TXCOMP);
pCdc->currentRcvBank = currentReceiveBank;
return nbBytesRcv;</P> <P>}

uint AT91F_UDP_Write(AT91PS_CDC pCdc, const char *pData, uint length)
{
AT91PS_UDP pUdp = pCdc->pUdp;
uint cpt = 0;</P> <P>        if ((pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXPKTRDY))
{
  return 0;//если усб готово к передаче, то начинаем её
}
pUdp->UDP_CSR[AT91C_EP_IN] &= ~(AT91C_UDP_TXCOMP);
cpt = MIN(length, AT91C_EP_IN_SIZE);
length -= cpt;
while (cpt--) pUdp->UDP_FDR[AT91C_EP_IN] = *pData++;
pUdp->UDP_CSR[AT91C_EP_IN] |= AT91C_UDP_TXPKTRDY;</P> <P> while (length) {
  cpt = MIN(length, AT91C_EP_IN_SIZE);
  length -= cpt;
  while (cpt--) pUdp->UDP_FDR[AT91C_EP_IN] = *pData++;
  while ( !(pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP) )
   if ( !AT91F_UDP_IsConfigured(pCdc) ) return length;
  pUdp->UDP_CSR[AT91C_EP_IN] &= ~(AT91C_UDP_TXCOMP);
  while (pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP);
  pUdp->UDP_CSR[AT91C_EP_IN] |= AT91C_UDP_TXPKTRDY;
}
return length;
}

pCDC.Read(&pCDC, ((char *) &data_comp), 2);
if ((length>256))
      {
pCDC.Write(&pCDC, data, length);
}

///
/// !Macros
/// - CLEAR_CSR
/// - SET_CSR

/// Bitmap for all status bits in CSR.
#define REG_NO_EFFECT_1_ALL      UDP_CSR_RX_DATA_BK0 | UDP_CSR_RX_DATA_BK1 \
                                |UDP_CSR_STALLSENT   | UDP_CSR_RXSETUP \
                                |UDP_CSR_TXCOMP

/// Clears the specified bit(s) in the UDP_CSR register.
/// \param endpoint The endpoint number of the CSR to process.
/// \param flags The bitmap to set to 1.
#define SET_CSR(endpoint, flags) \
    { \
        volatile unsigned int reg; \
        reg = UDP_CSR(UDP_BASE,endpoint); \
        reg |= REG_NO_EFFECT_1_ALL; \
        reg |= (flags); \
        UDP_CSR(UDP_BASE,endpoint) = reg; \
        while ( (UDP_CSR(UDP_BASE,endpoint) & (flags)) != (flags)); \
    }

/* Endpoint status setup */
typedef struct __UDP_EP_STATUS
{    
      INT size;        /* EP FIFO size */
    UINT32 type;    /* EP type (for store in CSR register) */
    UINT32 imask;    /* Interrupt flag in the IMR register (for enable/disable interrupt) */
    UINT32 banks;    /* Current receive bank for OUT endpoint, number of TX FIFO's for IN endpoint */
    
    P_UINT8 data;    /* Data buffer pointer */
    INT len;        /* Data size in buffer */
    INT inbuf;        /* For RX data count of buffered data */
    void (*fcbk)(void);    /* Optional transfer complete callback function */
    
} UDP_EP_STATUS, *P_UDP_EP_STATUS;

/* Receive Data from host host complete */
    if((AT91C_UDP_RX_DATA_BK0 | AT91C_UDP_RX_DATA_BK1) & csr)
    {    
        DBG_OUT("CSR%d RX: ", ep);
        if(p_eps->data)    /* Endpoint is in read state */
        {    
              if(p_eps->inbuf > 0)    /* Old EP FIFO not be fully readed */
                  cnt = p_eps->inbuf;
            else
                  cnt = (AT91C_UDP_RXBYTECNT & csr) >> 16;    /* Get data counter */
            
            if(p_eps->len >= cnt)    /* Room for new data exist */
            {
                p_eps->len -= cnt;    /* Add data to be readed */
                for(i = 0; i < cnt; i++)    /* Read new data */
                    *p_eps->data++ = AT91C_BASE_UDP->UDP_FDR[ep];
                p_eps->inbuf = 0;    /* No data in FIFO */
                ClrRxFlag(ep, p_eps);    /* Notify USB peripheral device that data have been read */
            }
            else    /* No room for all received bank */
            {    
                  p_eps->inbuf = cnt - p_eps->len;    /* Store number of bytes in EP FIFO */
                for(i = 0; i < p_eps->len; i++)    /* Read new data */
                    *p_eps->data++ = AT91C_BASE_UDP->UDP_FDR[ep];
                p_eps->len = 0;
            }
            
            /* Check read complete */
            if(!p_eps->len || cnt < p_eps->size)    /* OK */
            {
                p_eps->data = NULL;
                AT91C_BASE_UDP->UDP_IDR = p_eps->imask;    /* disable interrupt */
                if(p_eps->fcbk)    /* Call Rx Complete application callback */
                    p_eps->fcbk();
            }
        }
        else    /* Data buffer not set - application not wating data */
        {    
              DBG_OUT("NAK! Data buffer not set.\r\n");
            AT91C_BASE_UDP->UDP_IDR = p_eps->imask;    
        }
    }

/*******************************************************************************
Read data from endpoint
*******************************************************************************/
INT UDP_EP_Read(UINT8 ep, void *data, INT len, void (*fcbk)(void))
{    
      P_UDP_EP_STATUS p_eps;
        
    DBG_OUT("UDP_EP%d_Read: ", ep);
    
    if(!g_State.curr_cfg)    /* Check UDP device state */
    {    
          DBG_OUT("Device not configured!\r\n");
          return FALSE;    /* Not configured */
    }
    
    if(!ep || ep >= UDP_NUM_EP)    /* Check enpoint number */
    {    
          DBG_OUT("Invalid number %d!\r\n", ep);
          return FALSE;
    }
    
    p_eps = g_State.ep[ep];    /* Get endpoint status */
    if(!p_eps)    /* Check endpoint parameters */
    {    
          DBG_OUT("ep not inited!\r\n");
        return FALSE;
    }
    
    if(p_eps->data)
    {    
          DBG_OUT("ep busy!\r\n");
        return FALSE;
    }
    
    /* Set data fields */
    p_eps->data = data;
    p_eps->len = len;
    p_eps->fcbk = fcbk;
    
    AT91C_BASE_UDP->UDP_IER = p_eps->imask;        /* Enable interrupts from endpoint */
    DBG_OUT("\r\n");
    return TRUE;    /* Success */
}