/**
* @brief Prepares for a transmit operation.
*
* @param[in] usbp pointer to the @p USBDriver object
* @param[in] ep endpoint number
*
* @notapi
*/
void usb_lld_prepare_transmit(USBDriver *usbp, usbep_t ep) {
size_t n;
USBInEndpointState *isp = usbp->epc[ep]->in_state;
uint32_t epr = STM32_USB->EPR[ep];
/* Transfer initialization.*/
n = isp->txsize;
if (n > (size_t)usbp->epc[ep]->in_maxsize)
n = (size_t)usbp->epc[ep]->in_maxsize;
/* Double buffering is always enabled for isochronous endpoints, and
although we overlap the two buffers for simplicity, we still need
to write to the right counter. The DTOG_TX bit indicates the buffer
that is currently in use by the USB peripheral, that is, the buffer
from which the next packet will be sent, so we need to write the
counter of that buffer.*/
USB_GET_DESCRIPTOR(ep)->TXCOUNT0 = (stm32_usb_pma_t)n;
if (EPR_EP_TYPE_IS_ISO(epr) && (epr & EPR_DTOG_TX))
USB_GET_DESCRIPTOR(ep)->TXCOUNT1 = (stm32_usb_pma_t)n;
if (isp->txqueued)
usb_packet_write_from_queue(USB_GET_DESCRIPTOR(ep),
isp->mode.queue.txqueue, n);
else
usb_packet_write_from_buffer(USB_GET_DESCRIPTOR(ep),
isp->mode.linear.txbuf, n);
}
/**
* @brief Prepares for a transmit operation.
*
* @param[in] usbp pointer to the @p USBDriver object
* @param[in] ep endpoint number
*
* @notapi
*/
void usb_lld_prepare_transmit(USBDriver *usbp, usbep_t ep) {
size_t n;
USBInEndpointState *isp = usbp->epc[ep]->in_state;
/* Transfer initialization.*/
n = isp->txsize;
if (n > (size_t)usbp->epc[ep]->in_maxsize)
n = (size_t)usbp->epc[ep]->in_maxsize;
if (isp->txqueued)
usb_packet_write_from_queue(USB_GET_DESCRIPTOR(ep),
isp->mode.queue.txqueue, n);
else
usb_packet_write_from_buffer(USB_GET_DESCRIPTOR(ep),
isp->mode.linear.txbuf, n);
}