/*********************************************************************/
/* Copyright 1989 by H. Edward Hall                                  */
/*                                                                   */
/* Permission is hereby granted to copy and to give away this        */
/* software as long as this notice is preserved in its entirety.     */
/* You may modify the software or use it for any purpose just as     */
/* long as you preserve this notice and do not sell the software.    */
/* No warranty of any kind is made for this software.  The holder    */
/* of this copyright reserves the right to enhance and/or sell       */
/* this software with no obligation to provide updates or further    */
/* free copies; if this should happen you may still use this version */
/* of the software under the terms you received it with.             */
/*********************************************************************/

#ifdef TURBOC
#include <dos.h>
#endif TURBOC
#include "mpu401.h"

#define NBUFFERED 1024

/*
 * Tickle the MPU's registers.
 */
/*
 * The following should be about 3000 for an AT, 1000 for a PC;
 */
#define DELAYFACT 3000

static unsigned char databuf[NBUFFERED];
static int nbuffered = 0;
int
putcmd(cmd)
unsigned char cmd;
{
	register int x;

	x = 0;
	while ((inportb(STATUS_PORT)&DRR) != 0)
		if (x++ > DELAYFACT)
			return -1;

	disable();
	outportb(STATUS_PORT, cmd);
	for (;;)
	{
		x = 0;
		while ((inportb(STATUS_PORT)&RDY) != 0)
			if (x++ > DELAYFACT)
			{
				enable();
				return -1;
			}
		x = inportb(DATA_PORT)&0xff;
		if (x != ACK)
			databuf[nbuffered++] = (unsigned char)x;
		else
			break;
	}
	enable();
	return ACK;
}

int
getdata()
{
	register int x;

	if (nbuffered > 0)
		return (int)databuf[--nbuffered];
	x = 0;
	while ((inportb(STATUS_PORT)&RDY) != 0)
		if (x++ > DELAYFACT)
			return -1;
	return (inportb(DATA_PORT)&0xff);
}

int
putdata(val)
unsigned char val;
{
	register int x;

	x = 0;
	while ((inportb(STATUS_PORT)&DRR) != 0)
		if (x++ > DELAYFACT)
			return -1;

	outportb(DATA_PORT, val);
	return (int)val;
}