Reduce CPU load during interrupt handler

See https://github.com/esp8266/Arduino/pull/7057#issuecomment-591632232
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Jason2866 2020-02-27 09:52:48 +01:00 committed by GitHub
parent a776b8ac31
commit 9eb646085e
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@ -224,8 +224,8 @@ static ICACHE_RAM_ATTR void timer1Interrupt() {
endPin = 32 - __builtin_clz(waveformEnabled);
}
if (waveformEnabled) {
bool done = false;
if (waveformEnabled) {
do {
nextEventCycles = microsecondsToClockCycles(MAXIRQUS);
for (int i = startPin; i <= endPin; i++) {
@ -257,7 +257,13 @@ static ICACHE_RAM_ATTR void timer1Interrupt() {
// Check for toggles
int32_t cyclesToGo = wave->nextServiceCycle - now;
if (cyclesToGo < 0) {
cyclesToGo = -((-cyclesToGo) % (wave->nextTimeHighCycles + wave->nextTimeLowCycles));
// See #7057
// The following is a no-op unless we have overshot by an entire waveform cycle.
// As modulus is an expensive operation, this code is removed for now:
// cyclesToGo = -((-cyclesToGo) % (wave->nextTimeHighCycles + wave->nextTimeLowCycles));
//
// Alternative version with lower CPU impact:
// while (-cyclesToGo > wave->nextTimeHighCycles + wave->nextTimeLowCycles) { cyclesToGo += wave->nextTimeHighCycles + wave->nextTimeLowCycles)};
waveformState ^= mask;
if (waveformState & mask) {
if (i == 16) {