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/*
* Library to access MPU-401 hardware
*
* Copyright (C) 2014-2018 Mateusz Viste
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifdef MSDOS
#include <conio.h> /* inp() and outp() */
#else
#include "unixpio.h"
#endif
#include "timer.h"
#include "mpu401.h" /* include self for control */
#define MPU_DATA mpuport
#define MPU_STAT mpuport+1
/* flush everything from the MPU port (if anything) */
void mpu401_flush(int mpuport) {
while (mpu401_poll(mpuport) != 0) inp(MPU_DATA);
}
/* wait until it's okay for us to write to the MPU */
void mpu401_waitwrite(int mpuport) {
int buff;
for (;;) {
mpu401_flush(mpuport); /* make sure to flush first, in case the MPU */
buff = inp(MPU_STAT); /* tries to talk to us */
if ((buff & 0x40) == 0) break;
}
}
/* wait until it's okay for us to write to the MPU - but no longer than
* timeout us. returns 0 on success, non-zero otherwise. */
static int mpu401_waitwrite_timeout(int mpuport, long timeout) {
int buff;
unsigned long curtime, notafter;
timer_read(&notafter);
notafter += timeout;
for (;;) {
buff = inp(MPU_STAT);
if ((buff & 0x40) == 0) return(0);
timer_read(&curtime);
if (curtime >= notafter) return(-1);
}
}
/* polls the midi interface - returns 0 if nothing is available to be read, non-zero otherwise.
note that this should be checked as often as possible - whenever UART have some bytes for you, you MUST read them out */
int mpu401_poll(int mpuport) {
int buff;
buff = inp(MPU_STAT);
if ((buff & 0x80) == 0) return(1);
return(0);
}
void mpu401_waitread(int mpuport) {
while (mpu401_poll(mpuport) == 0);
}
/* resets the MPU-401. returns 0 on success, non-zero otherwise. */
int mpu401_rst(int mpuport) {
unsigned long curtime, timeout;
if (mpu401_waitwrite_timeout(mpuport, 2000000l) != 0) return(-1); /* wait for the MPU to accept bytes from us */
outp(MPU_STAT, 0xFF); /* Send MPU-401 RESET Command */
/* note that some cards do not ACK on 0xFF ! that's why I should wait for a timeout here, and skip waiting if no answer after 1 or 2s */
timer_read(&timeout);
timeout += 2000000l; /* timeout is 2s */
for (;;) {
/* wait for the MPU to hand a byte to us (we are waiting for an ACK) */
if (mpu401_poll(mpuport) != 0) {
if (inp(MPU_DATA) == 0xFE) break; /* if we got the ACK, continue */
}
timer_read(&curtime);
if (curtime >= timeout) break;
}
mpu401_flush(mpuport);
return(0);
}
void mpu401_uart(int mpuport) {
mpu401_waitwrite(mpuport); /* Wait for port ready */
outp(MPU_STAT, 0x3F); /* Set MPU-401 "Dumb UART" Mode */
/* I don't read anything back here, because MPU is not supposed to acknowledge the UART command */
}