The code snippet below shows the code handling single and double buffering mode
/* IN double Buffering*/
if (ep->doublebuffer == 0U)
{
ep->xfer_count = PCD_GET_EP_TX_CNT(hpcd->Instance, ep->num);
if (ep->xfer_count != 0)
{
PCD_WritePMA(hpcd->Instance, ep->xfer_buff, ep->pmaadress, ep->xfer_count);
}
}
else
{
if ((PCD_GET_ENDPOINT(hpcd->Instance, ep->num)& USB_EP_DTOG_TX) == USB_EP_DTOG_TX)
{
/*read from endpoint BUF0Addr buffer*/
ep->xfer_count = PCD_GET_EP_DBUF0_CNT(hpcd->Instance, ep->num);
if (ep->xfer_count != 0U)
{
PCD_WritePMA(hpcd->Instance, ep->xfer_buff, ep->pmaaddr0, ep->xfer_count);
}
}
else
{
/*read from endpoint BUF1Addr buffer*/
ep->xfer_count = PCD_GET_EP_DBUF1_CNT(hpcd->Instance, ep->num);
if (ep->xfer_count != 0U)
{
PCD_WritePMA(hpcd->Instance, ep->xfer_buff, ep->pmaaddr1, ep->xfer_count);
}
}
PCD_FreeUserBuffer(hpcd->Instance, ep->num, PCD_EP_DBUF_IN)
}
/*multi-packet on the NON control IN endpoint*/
ep->xfer_count = PCD_GET_EP_TX_CNT(hpcd->Instance, ep->num);
ep->xfer_buff+=ep->xfer_count;
In line 4 (single buffering) and lines 15 and 24 (double buffering), the xfer-count is set. In line 33, the transfer count is set again, with the single buffering value!
