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Ability to see how many Tx bytes are free in serial port buffer

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This commit is contained in:
Nicholas Sherlock 2015-06-23 00:30:37 +12:00
parent d0b940bf75
commit 6e504ca52a
13 changed files with 90 additions and 22 deletions
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40
src/main/drivers/serial_uart.c
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@ -211,7 +211,7 @@ void uartStartTxDMA(uartPort_t *s)
DMA_Cmd(s->txDMAChannel, ENABLE);
}
uint8_t uartTotalBytesWaiting(serialPort_t *instance)
uint8_t uartTotalRxBytesWaiting(serialPort_t *instance)
{
uartPort_t *s = (uartPort_t*)instance;
if (s->rxDMAChannel) {
@ -230,6 +230,41 @@ uint8_t uartTotalBytesWaiting(serialPort_t *instance)
}
}
uint8_t uartTotalTxBytesFree(serialPort_t *instance)
{
uartPort_t *s = (uartPort_t*)instance;
uint32_t bytesUsed;
if (s->port.txBufferHead >= s->port.txBufferTail) {
bytesUsed = s->port.txBufferHead - s->port.txBufferTail;
} else {
bytesUsed = s->port.txBufferSize + s->port.txBufferHead - s->port.txBufferTail;
}
if (s->txDMAChannel) {
/*
* When we queue up a DMA request, we advance the Tx buffer tail before the transfer finishes, so we must add
* the remaining size of that in-progress transfer here instead:
*/
bytesUsed += s->txDMAChannel->CNDTR;
/*
* If the Tx buffer is being written to very quickly, we might have advanced the head into the buffer
* space occupied by the current DMA transfer. In that case the "bytesUsed" total will actually end up larger
* than the total Tx buffer size, because we'll end up transmitting the same buffer region twice. (So we'll be
* transmitting a garbage mixture of old and new bytes).
*
* Be kind to callers and pretend like our buffer can only ever be 100% full.
*/
if (bytesUsed >= s->port.txBufferSize - 1) {
return 0;
}
}
return (s->port.txBufferSize - 1) - bytesUsed;
}
bool isUartTransmitBufferEmpty(serialPort_t *instance)
{
uartPort_t *s = (uartPort_t *)instance;
@ -281,7 +316,8 @@ void uartWrite(serialPort_t *instance, uint8_t ch)
const struct serialPortVTable uartVTable[] = {
{
uartWrite,
uartTotalBytesWaiting,
uartTotalRxBytesWaiting,
uartTotalTxBytesFree,
uartRead,
uartSetBaudRate,
isUartTransmitBufferEmpty,