#include <system.h>
#include <time.h>
#include "../irq/irq.h"
#include "pit.h"

volatile unsigned int _pit_ticks = 0;
volatile unsigned int _pit_frequency = 0;
unsigned char _pit_init = 0;
volatile TIME _internal_clock;


void i86_pit_set_frequency(int frequency)
{
      int divisor = 1193180/frequency;           // Calculate the divisor
      outportb(0x43, 0x36);               // Set our command byte 0x36
      outportb(0x40, divisor&0xFF);       // Set low byte
      outportb(0x40, divisor>>8);         // Set high byte
      _pit_frequency = frequency;
}

void i86_pit_handler(ISR_stack_regs *r)
{
      _pit_ticks++;                                  // count tick
      if (_pit_ticks % _pit_frequency == 0)
                  _CLOCK_INC((TIME*)&_internal_clock);   // update internal clock
}

unsigned int i86_pit_set_tick_count(unsigned int i)
{
      unsigned int r = _pit_ticks;
      _pit_ticks = i;
      return r;
}

unsigned int i86_pit_get_tick_count()
{
      return _pit_ticks;
}
unsigned int i86_pit_get_frequency()
{
      return _pit_frequency;
}

void i86_pit_install(int freq)
{
      i86_irq_install_handler(0, i86_pit_handler);
      i86_pit_set_frequency(freq);
      _pit_ticks = 0;
      _pit_init = 1;

}

unsigned char i86_pit_is_initialized()
{
      return _pit_init;
}