TreelLab/prog/sources/time.cpp

#include "all-headers.h"

static volatile uint32_t gUptime;

static void startSystick (BOOT_MODE) {
	SYST_RVR = CPU_MHZ * 1000 - 1 ; // Underflow every ms
	SYST_CVR = 0 ;
	SYST_CSR = SYST_CSR_CLKSOURCE | SYST_CSR_ENABLE ;

	// Configure and chain PIT0 and PIT1 for 64-bit counting

	// Power on PIT
	SIM_SCGC6 |= SIM_SCGC6_PIT ;

	// Enable PIT module
	PIT_MCR = 0 ;

	// Disable PIT0 and PIT1
	PIT_TCTRL (0) = 0 ;
	PIT_TCTRL (1) = 0 ;

	// PIT0 and PIT1 down-count: initialize them with all 1's
	PIT_LDVAL (0) = UINT32_MAX ;
	PIT_LDVAL (1) = UINT32_MAX ;

	// Enable PIT0 and PIT1: start counting, chain PI1 to PIT0, no interrupt
	PIT_TCTRL (1) = PIT_TCTRL_CHN | PIT_TCTRL_TEN ;
	PIT_TCTRL (0) = PIT_TCTRL_TEN ;
}

MACRO_BOOT_ROUTINE (startSystick);

static void activateSystickInterrupt (INIT_MODE) {
	SYST_CSR |= SYST_CSR_TICKINT;
}

MACRO_INIT_ROUTINE (activateSystickInterrupt);

void busyWaitDuring_initMode (INIT_MODE_ const uint32_t inDelayMS) {
	const uint32_t COUNTFLAG_MASK = 1 << 16 ;
	for (uint32_t i=0 ; i<inDelayMS ; i++) {
		while ((SYST_CSR & COUNTFLAG_MASK) == 0) {} // Busy wait, polling COUNTFLAG
	}
}

void busyWaitDuring (USER_MODE_ const uint32_t inDelayMS) {
	busyWaitUntil(MODE_ gUptime + inDelayMS);
}

void busyWaitUntil (USER_MODE_ const uint32_t inDeadLineMS) {
	while (inDeadLineMS > gUptime) {}
}

void systickInterruptServiceRoutine (SECTION_MODE) {
	const uint32_t newUptime = gUptime + 1 ;
	gUptime = newUptime ;

	// Run every section routines in real.time.interrupt.routine.array
	extern void (* __real_time_interrupt_routine_array_start) (SECTION_MODE_ const uint32_t inUptime) ;
	extern void (* __real_time_interrupt_routine_array_end) (SECTION_MODE_ const uint32_t inUptime) ;
	void (** ptr) (SECTION_MODE_ const uint32_t) = & __real_time_interrupt_routine_array_start ;
	while (ptr != & __real_time_interrupt_routine_array_end) {
		(* ptr) (MODE_ newUptime) ;
		ptr ++ ;
	}
}

uint32_t millis(ANY_MODE) {
	return gUptime;
}

uint64_t section_micros(SECTION_MODE) {

	// To obtain the correct value, first read LTMR64H and then LTMR64L
	uint64_t result = PIT_LTMR64H ;
	result <<= 32 ;
	result |= PIT_LTMR64L ;

	// PIT0 and PIT1 actually downcount
	result = ~ result ;

	// Divide by the clock frequency in MHz for getting microsecond count
	result /= busMHZ () ;

	return result;
}

uint32_t systick(ANY_MODE) {
	return SYST_CVR;
}