kernel.soso/timer.c


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#include "timer.h"
#include "isr.h"
#include "screen.h"
#include "process.h"
#include "common.h"

#define TIMER_FREQ 1000

uint32 gSystemTickCount = 0;

BOOL gSchedulerEnabled = FALSE;

//called from assembly
void handleTimerIRQ(TimerInt_Registers registers) {
    gSystemTickCount++;

    if (/*gSystemTickCount % 10 == 0 &&*/ gSchedulerEnabled == TRUE) {
        schedule(&registers);
    }
}

uint32 getSystemTickCount() {
    return gSystemTickCount;
}

uint32 getUptimeSeconds() {
    return gSystemTickCount / TIMER_FREQ;
}

uint32 getUptimeMilliseconds() {
    return gSystemTickCount;
}

void enableScheduler() {
    gSchedulerEnabled = TRUE;
}

void disableScheduler() {
    gSchedulerEnabled = FALSE;
}

static void initTimer(uint32 frequency) {
    uint32 divisor = 1193180 / frequency;

    outb(0x43, 0x36);

    uint8 l = (uint8)(divisor & 0xFF);
    uint8 h = (uint8)( (divisor>>8) & 0xFF );

    outb(0x40, l);
    outb(0x40, h);
}

void initializeTimer() {
    initTimer(TIMER_FREQ);
}