From d50e59781ecfd80a366cd0bb0b30374b1536247a Mon Sep 17 00:00:00 2001 From: John Holman Date: Tue, 24 Oct 2017 22:18:38 +0100 Subject: Create macro to guard critical sections for large transmit buffers New macro TX_BUFFER_ATOMIC makes the following code block atomic only if the transmit buffer is larger than 256 bytes. SREG is restored on completion. The macro is then used to simplify code for availableForWrite() --- cores/arduino/HardwareSerial.cpp | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/cores/arduino/HardwareSerial.cpp b/cores/arduino/HardwareSerial.cpp index 5cd89e5..75e079f 100644 --- a/cores/arduino/HardwareSerial.cpp +++ b/cores/arduino/HardwareSerial.cpp @@ -26,6 +26,7 @@ #include #include #include +#include #include "Arduino.h" #include "HardwareSerial.h" @@ -76,6 +77,13 @@ void serialEventRun(void) #endif } +// macro to guard critical sections when needed for large TX buffer sizes +#if (SERIAL_TX_BUFFER_SIZE>256) +#define TX_BUFFER_ATOMIC ATOMIC_BLOCK(ATOMIC_RESTORESTATE) +#else +#define TX_BUFFER_ATOMIC +#endif + // Actual interrupt handlers ////////////////////////////////////////////////////////////// void HardwareSerial::_tx_udr_empty_irq(void) @@ -177,15 +185,13 @@ int HardwareSerial::read(void) int HardwareSerial::availableForWrite(void) { -#if (SERIAL_TX_BUFFER_SIZE>256) - uint8_t oldSREG = SREG; - cli(); -#endif - tx_buffer_index_t head = _tx_buffer_head; - tx_buffer_index_t tail = _tx_buffer_tail; -#if (SERIAL_TX_BUFFER_SIZE>256) - SREG = oldSREG; -#endif + tx_buffer_index_t head; + tx_buffer_index_t tail; + + TX_BUFFER_ATOMIC { + head = _tx_buffer_head; + tail = _tx_buffer_tail; + } if (head >= tail) return SERIAL_TX_BUFFER_SIZE - 1 - head + tail; return tail - head - 1; } -- cgit v1.2.3-18-g5258