#include	"u.h"
#include	"lib.h"
#include	"mem.h"
#include	"dat.h"
#include	"fns.h"
#include	"io.h"
#include	"ureg.h"

/*
 *  8253 timer
 */
enum
{
	T0cntr=	0x40,		/* counter ports */
	T1cntr=	0x41,		/* ... */
	T2cntr=	0x42,		/* ... */
	Tmode=	0x43,		/* mode port */

	Load0square=	0x36,		/*  load counter 0 with 2 bytes,
					 *  output a square wave whose
					 *  period is the counter period
					 */
	Freq=		1193182,	/* Real clock frequency */
	FHZ=		1000,		/* hertz for fast clock */
};

/*
 *  delay for l milliseconds
 */
void
delay(int l)
{
	int i;

	while(--l){
		for(i=0; i < 404; i++)
			;
	}
}

void
clockinit(void)
{
	/*
	 *  set vector for clock interrupts
	 */
	setvec(Clockvec, clock);

	/*
	 *  make clock output a square wave with a 1/HZ period
	 */
	outb(Tmode, Load0square);
	outb(T0cntr, (Freq/HZ));	/* low byte */
	outb(T0cntr, (Freq/HZ)>>8);	/* high byte */
}

void
clock(Ureg *ur)
{
	Proc *p;

	m->ticks++;

	checkalarms();
	mouseclock();

	/*
	 *  process time accounting
	 */
	p = m->proc;
	if(p){
		p->pc = ur->pc;
		if (p->state==Running)
			p->time[p->insyscall]++;
	}

	if(u && p && p->state==Running){
		/*
		 *  preemption
		 */
		if(anyready()){
			if(p->hasspin)
				p->hasspin = 0;
			else
				sched();
		}
		/*
		 *  notes for processes that might be spinning
		 *  in user mode.
		 */
		if((ur->cs&0xffff) == UESEL){
			if(u->nnote)
				notify(ur);
		}
	}
}

/*
 *  a faster (1 MS) clock tick for a non-interrupting serial port or
 *  kernel profiling.  m->ticks still increments as usual.
 */
void
fclock(Ureg *ur)
{
	static ulong ticks;

	uartintr0(ur);		/* poll the serial port */
	if((ticks++ % (FHZ/HZ)) == 0)
		clock(ur);
}

void
fclockinit(void)
{
	int x;

	/*
	 *  set vector for clock interrupts
	 */
	setvec(Clockvec, fclock);

	/*
	 *  make clock output a square wave with a 1/FHZ period
	 */
	x = splhi();
	outb(Tmode, Load0square);
	outb(T0cntr, (Freq/FHZ));	/* low byte */
	outb(T0cntr, (Freq/FHZ)>>8);	/* high byte */
	splx(x);
}