/***
 ***	pmon code
 ***
 ***	This code has been borrowed.
 ***/

/***
 ***	Include files
 ***/
#include <ctype.h>
#include <conio.h>
#include <dos.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "pragmas.h"
#include "pinewood.h"

/*
 * From orstcs!rutgers!shelby!agate!ucbvax!ucsd!swrinde!cs.utexas.edu!uunet!sugar!sms Sun Mar 18 22:14:10 PST 1990
 * Article 1373 of alt.msdos.programmer:
 * Path: orstcs!rutgers!shelby!agate!ucbvax!ucsd!swrinde!cs.utexas.edu!uunet!sugar!sms
 * From: sms@sugar.hackercorp.com (Stanley M. Sutton)
 * Newsgroups: alt.msdos.programmer
 * Subject: Microsecond timer for IBM PC Compatibles
 * Message-ID: <5397@sugar.hackercorp.com>
 * Date: 17 Mar 90 08:14:55 GMT
 * Reply-To: sms@sugar.hackercorp.com (Stanley M. Sutton)
 * Distribution: alt
 * Organization: Sugar Land Unix - Houston
 * Lines: 149
 * 
 * Here is a public domain set of routines for timing events to
 * the resolution of the PC clock.  It is very consistent accross both
 * 8088s, 80286s, and 80386s.  The routine is compilable with TurboC.
 * This is very short, so I'm posting to alt.msdos.programmers
 * and alt.sources.
 */

#pragma inline
#define OUT outportb
#define IN  inportb
#define DIS disable
#define ENB enable

static unsigned long far	*_Dos_time = MK_FP(0x40, 0x6C);
static unsigned int		Pmon_ovhead = 0xFFFF;

void
get_time(US_TIME *us_time)
    {
    DIS();
    OUT(0x43, 0);
    us_time->tick = *_Dos_time;
    us_time->timer = IN(0x40);

#ifdef __TURBOC__
asm jmp $+2;
#endif

    us_time->timer += ((unsigned int)(IN(0x40)) << 8);
    ENB();

    /* A quick hack to check the timer if the time is close to roll-over */
    if (us_time->timer < 1000)
	{
	DIS();
	OUT(0x43, 0);
	us_time->tick = *_Dos_time;
	us_time->timer = IN(0x40);

#ifdef __TURBOC__
asm jmp $+2;
#endif

	us_time->timer += ((unsigned int)(IN(0x40)) << 8);
	ENB();
	}
    }

unsigned long
delta_us(US_TIME *s_time, US_TIME *e_time)
    {
    if (Pmon_ovhead == 0xFFFF)
	calib_pmon();

    return ((((e_time->tick - s_time->tick) << 16) +
            s_time->timer - e_time->timer - Pmon_ovhead) * 84 / 100);
    }

void
calib_pmon(void)
    {
    US_TIME			e_time;
    US_TIME			s_time;

    OUT(0x43, 0x34);
#ifdef __TURBOC__
asm jmp $+2;
#endif
    OUT(0x40, 0);
#ifdef __TURBOC__
asm jmp $+2;
#endif
    OUT(0x40, 0);
    get_time(&s_time);
    get_time(&e_time);
    Pmon_ovhead = (unsigned int) ((e_time.tick - s_time.tick) << 16) +
		                   s_time.timer - e_time.timer;
    }