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#include <stdio.h>
#include <dos.h>
#include "mpu.h"


/* 
 * Global variable holding the MPU-401 base address
 * Has to be set before calling any function if different from the
 * default 0x330
 */
 
int mpu_base = 0x330;


/* mpu_wait_drr():
**	wait for MPU ready to receive a command, with timeout.
*/

int mpu_wait_drr()
{
	long counter;
	int stat;

	for (counter = 0xFFFFL; counter != 0; --counter) {
		if ((stat = inp(mpu_base + MPUP_STAT) & MPUPS_DRR) == 0)
			break;
	}
	return (stat);
}


/* mpu_wait_dsr():
**	wait for MPU ready to send data, with timeout.
*/

int mpu_wait_dsr()
{
	long counter;
	int stat;

	for (counter = 0xFFFFL; counter != 0; --counter) {
		if ((stat = inp(mpu_base + MPUP_STAT) & MPUPS_DSR) == 0)
			break;
	}
	return (stat);
}


/* mpu_dsr():
**	check if data waiting.
*/

int mpu_dsr()
{
	return (inp(mpu_base + MPUP_STAT) & MPUPS_DSR);
}


/* mpu_put(byte):
**	put out a single byte command & wait for the ack.
*/

void mpu_put(unsigned char cmd)
{
	long counter;
	int ack;

	(void) mpu_wait_drr();
	outp(mpu_base + MPUP_COMD, cmd);
	for (counter = 0xFFL; counter != 0; --counter) {
		if (mpu_wait_dsr()) {		/* timed out */
			fprintf(stderr, "DSR timeout\n");
			break;
		}

		if (mpu_dget() == CMD_ACK)
			break;
	}
}


/* mpu_dput(data):
**	put out a single data byte
*/

void mpu_dput(unsigned char data)
{
	if (mpu_wait_drr()) {
		fprintf(stderr, "DRR timeout\n");
		return;
	}
	outp(mpu_base + MPUP_DATA, data);
}


/* mpu_dget():
**	get data byte if available, else return -1
*/

int mpu_dget()
{
	int data = -1;

	if (! mpu_dsr()) {
		asm cli
		data = inp(mpu_base + MPUP_DATA);
		asm sti
	}
	return (data);
}


/* mpu_exit_uart():
**	exit UART mode (by sending a reset)
*/

void mpu_exit_uart(void)
{
	(void) mpu_wait_drr();
	outp(mpu_base + MPUP_COMD, CMD_RESET);
}
.

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