import platform.pch.pic as pic
import platform.pch.pit as pit
import sched.sched as sched
import asm
import t, c

TIMER_FREQUENCY:       t.CDefine = 1000
TICKS_PER_SECOND:      t.CDefine = TIMER_FREQUENCY
MILLISECONDS_PER_TICK: t.CDefine = (1000 / TIMER_FREQUENCY)

ticks:         t.CStatic | t.CVolatile | t.CUInt64T = 0
seconds:       t.CStatic | t.CVolatile | t.CUInt32T = 0
milliseconds:  t.CStatic | t.CVolatile | t.CUInt32T = 0
timer_running: t.CStatic | t.CVolatile | bool       = False

def timer_init():
    global ticks, seconds, milliseconds, timer_running
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])
    ticks = 0
    seconds = 0
    milliseconds = 0
    timer_running = True
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])
    pit.pit_init(TIMER_FREQUENCY)

def timer_handler():
    global ticks, seconds, milliseconds, timer_running
    if not timer_running:
        pic.eoi(0)
        return
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])
    ticks = ticks + 1
    milliseconds = milliseconds + MILLISECONDS_PER_TICK
    if milliseconds >= 1000:
        seconds = seconds + 1
        milliseconds = milliseconds - 1000
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])
    sched.Scheduler.sched_tick()
    pic.eoi(0)

def timer_start():
    global timer_running
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])
    timer_running = True
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])

def timer_stop():
    global timer_running
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])
    timer_running = False
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])

def timer_reset():
    global ticks, seconds, milliseconds
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])
    ticks = 0
    seconds = 0
    milliseconds = 0
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])

def timer_get_ticks() -> t.CUInt64T:
    current_ticks: t.CUInt64T
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])
    current_ticks = ticks
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])
    return current_ticks

def timer_get_seconds() -> t.CUInt32T:
    current_seconds: t.CUInt32T
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])
    current_seconds = seconds
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])
    return current_seconds

def timer_get_milliseconds() -> t.CUInt32T:
    current_milliseconds: t.CUInt32T
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])
    current_milliseconds = milliseconds
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])
    return current_milliseconds

def timer_get_time(out_seconds: t.CUInt32T | t.CPtr, out_milliseconds: t.CUInt32T | t.CPtr):
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])
    if out_seconds:
        c.Set(c.Deref(out_seconds), seconds)
    if out_milliseconds:
        c.Set(c.Deref(out_milliseconds), milliseconds)
    c.Asm("mfence", op=[t.ASM_DESCR.CLOBBER_MEMORY])

def timer_msleep(ms: t.CUInt32T):
    target: t.CUInt64T = ticks + (ms + MILLISECONDS_PER_TICK - 1) / MILLISECONDS_PER_TICK
    while ticks < target:
        asm.sti()
        asm.hlt()
        sched.Scheduler._yield()

def timer_sleep(sec: t.CUInt32T):
    target: t.CUInt64T = ticks + sec * TICKS_PER_SECOND
    while ticks < target:
        asm.sti()
        asm.hlt()
        sched.Scheduler._yield()