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Fix USART total bytes waiting when tx/rx buffer sizes are not equal. 

Avoid using % operator.  Allow buffer sizes that are not powers of two.
This commit is contained in:
Dominic Clifton 2014-12-13 02:46:13 +00:00
parent 27ae6fdb72
commit 9b81dea320
2 changed files with 21 additions and 10 deletions
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28
src/main/drivers/serial_uart.c
View File

@ -205,10 +205,18 @@ void uartStartTxDMA(uartPort_t *s)
uint8_t uartTotalBytesWaiting(serialPort_t *instance)
{
uartPort_t *s = (uartPort_t*)instance;
if (s->rxDMAChannel)
return (s->rxDMAChannel->CNDTR - s->rxDMAPos) & (s->port.txBufferSize - 1);
else {
return (s->port.rxBufferHead - s->port.rxBufferTail) & (s->port.txBufferSize - 1);
if (s->rxDMAChannel) {
if (s->rxDMAChannel->CNDTR > s->rxDMAPos) {
return s->rxDMAChannel->CNDTR - s->rxDMAPos;
} else {
return s->rxDMAPos - s->rxDMAChannel->CNDTR;
}
}
if (s->port.rxBufferHead > s->port.rxBufferTail) {
return s->port.rxBufferHead - s->port.rxBufferTail;
} else {
return s->port.rxBufferTail - s->port.rxBufferHead;
}
}
@ -231,8 +239,10 @@ uint8_t uartRead(serialPort_t *instance)
if (--s->rxDMAPos == 0)
s->rxDMAPos = s->port.rxBufferSize;
} else {
ch = s->port.rxBuffer[s->port.rxBufferTail];
s->port.rxBufferTail = (s->port.rxBufferTail + 1) % s->port.rxBufferSize;
ch = s->port.rxBuffer[s->port.rxBufferTail++];
if (s->port.rxBufferTail >= s->port.rxBufferSize) {
s->port.rxBufferTail = 0;
}
}
return ch;
@ -241,8 +251,10 @@ uint8_t uartRead(serialPort_t *instance)
void uartWrite(serialPort_t *instance, uint8_t ch)
{
uartPort_t *s = (uartPort_t *)instance;
s->port.txBuffer[s->port.txBufferHead] = ch;
s->port.txBufferHead = (s->port.txBufferHead + 1) % s->port.txBufferSize;
s->port.txBuffer[s->port.txBufferHead++] = ch;
if (s->port.txBufferHead >= s->port.txBufferSize) {
s->port.txBufferHead = 0;
}
if (s->txDMAChannel) {
if (!(s->txDMAChannel->CCR & 1))

3
src/main/drivers/serial_uart.h
View File

@ -17,8 +17,7 @@
#pragma once
// FIXME since serial ports can be used for any function these buffer sizes probably need normalising.
// Code is optimal when buffer sizes are powers of 2 due to use of % and / operators.
// Since serial ports can be used for any function these buffer sizes probably need normalising.
#define UART1_RX_BUFFER_SIZE 256
#define UART1_TX_BUFFER_SIZE 192
#define UART2_RX_BUFFER_SIZE 256