static inline int usbd_cdc_Start_Rx(void *pdev)
{
/* USB_Rx_Buffer_length is used here to keep track of
* available _contiguous_ buffer space in USB_Rx_Buffer.
*/
uint32_t USB_Rx_length;
if (USB_Rx_Buffer_head >= USB_Rx_Buffer_tail)
USB_Rx_Buffer_length = USB_RX_BUFFER_SIZE;
USB_Rx_length = ring_space_contig(USB_Rx_Buffer_length, USB_Rx_Buffer_head, USB_Rx_Buffer_tail);
if (USB_Rx_length < CDC_DATA_OUT_PACKET_SIZE) {
USB_Rx_length = ring_space_wrapped(USB_Rx_Buffer_length, USB_Rx_Buffer_head, USB_Rx_Buffer_tail);
if (USB_Rx_length < CDC_DATA_OUT_PACKET_SIZE) {
if (USB_Rx_State) {
USB_Rx_State = 0;
DCD_SetEPStatus(pdev, CDC_OUT_EP, USB_OTG_EP_TX_NAK);
}
return 0;
}
USB_Rx_Buffer_length = USB_Rx_Buffer_head;
USB_Rx_Buffer_head = 0;
if (USB_Rx_Buffer_tail == USB_Rx_Buffer_length)
USB_Rx_Buffer_tail = 0;
}
if (!USB_Rx_State) {
USB_Rx_State = 1;
DCD_SetEPStatus(pdev, CDC_OUT_EP, USB_OTG_EP_TX_VALID);
}
DCD_EP_PrepareRx(pdev,
CDC_OUT_EP,
USB_Rx_Buffer + USB_Rx_Buffer_head,
CDC_DATA_OUT_PACKET_SIZE);
return 1;
}
while (serial.available() > 0) {
(void)serial.read();
}
}
test(0_USBSERIAL_RingBufferHelperIsSane) {
uint32_t size = 129;
uint32_t head = 0;
uint32_t tail = 0;
head = 0;
tail = 0;
assertEqual(0, ring_data_avail(size, head, tail));
assertEqual(128, ring_space_avail(size, head, tail));
assertEqual(0, ring_data_contig(size, head, tail));
assertEqual(128, ring_space_contig(size, head, tail));
assertEqual(0, ring_space_wrapped(size, head, tail));
head = 63;
tail = 0;
assertEqual(63, ring_data_avail(size, head, tail));
assertEqual(65, ring_space_avail(size, head, tail));
assertEqual(63, ring_data_contig(size, head, tail));
assertEqual(65, ring_space_contig(size, head, tail));
assertEqual(0, ring_space_wrapped(size, head, tail));
head = 63;
tail = 32;
assertEqual(31, ring_data_avail(size, head, tail));
assertEqual(97, ring_space_avail(size, head, tail));
assertEqual(31, ring_data_contig(size, head, tail));