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#include "ch.h"
#include "timer.h"
static uint32_t reset_point = 0;
#if CH_CFG_ST_RESOLUTION < 32
static uint32_t last_systime = 0;
static uint32_t overflow = 0;
#endif
void timer_init(void) { timer_clear(); }
void timer_clear(void) {
reset_point = (uint32_t)chVTGetSystemTime();
#if CH_CFG_ST_RESOLUTION < 32
last_systime = reset_point;
overflow = 0;
#endif
}
uint16_t timer_read(void) { return (uint16_t)timer_read32(); }
uint32_t timer_read32(void) {
uint32_t systime = (uint32_t)chVTGetSystemTime();
#if CH_CFG_ST_RESOLUTION < 32
// If/when we need to support 64-bit chips, this may need to be modified to match the native bit-ness of the MCU.
// At this point, the only SysTick resolution allowed other than 32 is 16 bit.
// In the 16-bit case, at:
// - CH_CFG_ST_FREQUENCY = 100000, overflow will occur every ~0.65 seconds
// - CH_CFG_ST_FREQUENCY = 10000, overflow will occur every ~6.5 seconds
// - CH_CFG_ST_FREQUENCY = 1000, overflow will occur every ~65 seconds
// With this implementation, as long as we ensure a timer read happens at least once during the overflow period, timing should be accurate.
if (systime < last_systime) {
overflow += ((uint32_t)1) << CH_CFG_ST_RESOLUTION;
}
last_systime = systime;
return (uint32_t)TIME_I2MS(systime - reset_point + overflow);
#else
return (uint32_t)TIME_I2MS(systime - reset_point);
#endif
}
uint16_t timer_elapsed(uint16_t last) { return TIMER_DIFF_16(timer_read(), last); }
uint32_t timer_elapsed32(uint32_t last) { return TIMER_DIFF_32(timer_read32(), last); }
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