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Interrupt safety fixes for HardwareSerial #1213

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Merged
merged 2 commits into from
Dec 14, 2015
Merged

Interrupt safety fixes for HardwareSerial #1213

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afbc049
Make the circular buffer's _size and _bufend members immutable.
alltheblinkythings Dec 10, 2015
55e0dab
Protect HardwareSerial's cbuf usage with InterruptLock.
alltheblinkythings Dec 14, 2015
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40 changes: 29 additions & 11 deletions cores/esp8266/HardwareSerial.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
#include <inttypes.h>
#include "Arduino.h"
#include "cbuf.h"
#include "interrupts.h"

extern "C" {
#include "osapi.h"
Expand Down Expand Up @@ -556,6 +557,7 @@ int HardwareSerial::available(void) {
int result = 0;

if (_uart != NULL && _uart->rxEnabled) {
InterruptLock il;
result = static_cast<int>(_rx_buffer->getSize());
}

Expand All @@ -570,6 +572,7 @@ int HardwareSerial::peek(void) {
if(_uart == 0)
return -1;
if(_uart->rxEnabled) {
InterruptLock il;
return _rx_buffer->peek();
} else {
return -1;
Expand All @@ -580,6 +583,7 @@ int HardwareSerial::read(void) {
if(_uart == 0)
return -1;
if(_uart->rxEnabled) {
InterruptLock il;
return _rx_buffer->read();
} else {
return -1;
Expand All @@ -590,6 +594,7 @@ int HardwareSerial::availableForWrite(void) {
if(_uart == 0)
return 0;
if(_uart->txEnabled) {
InterruptLock il;
return static_cast<int>(_tx_buffer->room());
} else {
return 0;
Expand All @@ -604,28 +609,41 @@ void HardwareSerial::flush() {
if(!_written)
return;

while(_tx_buffer->getSize() || uart_get_tx_fifo_room(_uart) < UART_TX_FIFO_SIZE)
while(true) {
{
InterruptLock il;
if(_tx_buffer->getSize() == 0 &&
uart_get_tx_fifo_room(_uart) >= UART_TX_FIFO_SIZE) {
break;
}
}
yield();

}
_written = false;
}

size_t HardwareSerial::write(uint8_t c) {
if(_uart == 0 || !_uart->txEnabled)
return 0;
_written = true;
size_t room = uart_get_tx_fifo_room(_uart);
if(room > 0 && _tx_buffer->empty()) {
uart_transmit_char(_uart, c);
return 1;
}

while(_tx_buffer->room() == 0) {
while(true) {
{
InterruptLock il;
if(_tx_buffer->empty()) {
if(uart_get_tx_fifo_room(_uart) > 0) {
uart_transmit_char(_uart, c);
} else {
_tx_buffer->write(c);
uart_arm_tx_interrupt(_uart);
}
break;
} else if(_tx_buffer->write(c)) {
break;
}
}
yield();
}

_tx_buffer->write(c);
uart_arm_tx_interrupt(_uart);
return 1;
}

Expand Down
4 changes: 2 additions & 2 deletions cores/esp8266/cbuf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -113,9 +113,9 @@ class cbuf {
return (ptr == _bufend) ? _buf : ptr;
}

size_t _size;
const size_t _size;
char* _buf;
char* _bufend;
const char* const _bufend;
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two time const?

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That's a const pointer to chars which are const, so _bufend is const and *_bufend is const as well.

char* _begin;
char* _end;
};
Expand Down