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[beken-72xx] Fix micros() usage with disabled interrupts (#28)

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* Workaround for micros when used inside interruptLock blocks

* Fix comment formatting

* Cover case when millis overflows

* Improve variable names.
This commit is contained in:
David Buezas
2022-10-05 12:51:20 +02:00
committed by GitHub
parent 303def49cb
commit 3e691de24a
1 changed files with 25 additions and 3 deletions
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28
arduino/beken-72xx/cores/arduino/wiring.c
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@@ -8,8 +8,8 @@
#include <sys_rtos.h>
#define TICKS_PER_US (CFG_XTAL_FREQUENCE / 1000 / 1000)
#define TIMER0_US_OVERFLOW (portTICK_PERIOD_MS * 1000)
#define TICKS_PER_OVERFLOW (TICKS_PER_US * TIMER0_US_OVERFLOW)
#define US_PER_OVERFLOW (portTICK_PERIOD_MS * 1000)
#define TICKS_PER_OVERFLOW (TICKS_PER_US * US_PER_OVERFLOW)
void delayMilliseconds(unsigned long ms) {
rtos_delay_milliseconds(ms);
@@ -66,7 +66,29 @@ unsigned long micros() {
#endif
#if LT_MICROS_HIGH_RES
return millis() * 1000 + getTicksCount() / (CFG_XTAL_FREQUENCE / 1000 / 1000);
static uint32_t lastMillis = 0;
static uint32_t correctedMillis = 0;
static uint32_t lastTicks = 0;
uint32_t nowMillis = millis();
uint32_t nowTicks = getTicksCount();
bool tickOverflow = nowTicks < lastTicks;
bool millisUpdated = nowMillis != lastMillis;
if (millisUpdated) {
/* reset artificially corrected millis */
correctedMillis = nowMillis;
} else if (tickOverflow) {
/*
This can happen if micros is called from within a interruptLock block (interrupts disabled).
In this case, if the tick counter rolls over, millis() won't be updated, and micros will
lag by US_PER_OVERFLOW milliseconds (one rollover).
The workaround only works as long as micros() calls happen within 2ms of eachother.
WARNING: if interrupts are disabled for more than 2ms, micros() and millis() will temporarily get out of sync.
*/
correctedMillis += portTICK_PERIOD_MS;
}
lastMillis = nowMillis;
lastTicks = nowTicks;
return correctedMillis * 1000 + nowTicks / (CFG_XTAL_FREQUENCE / 1000 / 1000);
#else
#if 0
REG_WRITE(TIMER3_5_READ_CTL, (BKTIMER3 << 2) | 1);