#include <Arch/Timer.h>
#include <Arch/GIC.h>
#include <OS/Scheduler.h>
#include <Arch/Exceptions.h>

static volatile UInt64 sTimerCounter = 0;

void TimerInitialize() {
    GICEnableInterrupt(kTimerIRQ);
    TimerReset(kTimerFrequency);
}

void TimerReset(UInt64 interval) {
    UInt64 frequency;
    __asm__ volatile ("mrs %0, cntfrq_el0" : "=r"(frequency));
    __asm__ volatile ("msr cntv_tval_el0, %0" :: "r"(frequency /interval));
    __asm__ volatile ("msr cntv_ctl_el0, %0" :: "r"((UInt64)1));
}

Address TimerHandler(ExceptionsContext* frame) {
    sTimerCounter++;
    TimerReset(kTimerFrequency);
    return SchedulerNext((Address)frame);
}

UInt64 TimerGetCounter() {
    return sTimerCounter;
}