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/*
* SoundBlaster DSP code
* This file is part of the DOSMid project
* Copyright (C) Mateusz Viste 2015
*/
#ifdef MSDOS
#include <conio.h> /* inp() and outp() */
#else
#include "unixpio.h"
#endif
#include "timer.h"
#include "sbdsp.h" /* include self for control */
/* convenience defines for the I/O addresses of the SoundBlaster */
#define IO_RESET (port+0x06)
#define IO_READ (port+0x0A)
#define IO_WRITE (port+0x0C)
#define IO_WRSTAT (port+0x0C)
#define IO_RDSTAT (port+0x0E)
int dsp_reset(unsigned short port) {
/* 1. Write a "1" to the Reset port (2x6h) and wait for 3 microseconds.
* 2. Write a "0" to the Reset port.
* 3. Poll for a ready byte 0AAh from the Read Data port. You must check the
* the Read-Buffer Status port to ensure there is data before reading the
* Read Data port. */
int x, timeout;
outp(IO_RESET, 1);
udelay(2000); /* wait 2 ms */
outp(IO_RESET, 0);
/* wait for the DSP to give us the green light - no longer than 50ms (the
* SoundBlaster docs state that the DSP should init in about 100us) */
for (timeout = 50; timeout != 0; timeout--) {
udelay(1000); /* wait 1 ms */
/* check that we got something on the data port */
x = dsp_read(port);
if (x < 0) continue; /* nothing available yet */
if (x == 0xAA) return(0); /* 0xAA means 'OK' */
return(-1); /* otherwise there's a problem */
}
/* if we are here, then a timeout occured */
return(-1);
}
int dsp_read(unsigned short port) {
/* When DSP data is available, it can be read in from the Read Data port.
* Before the data is read in, bit-7 of the Read-Buffer Status port must be
* checked to ensure that there is data to read. If bit-7 is 1, then there
* is data to read. Otherwise, no data is available. */
if ((inp(IO_RDSTAT) & 128) == 0) return(-1); /* nothing to read */
return(inp(IO_READ));
}
void dsp_write(unsigned short port, int databyte) {
/* DSP commands and data are sent through the Write Command/Data port.
* Before data is written to the DSP, bit-7 of the Write-Buffer Status port
* must be checked to ensure that the DSP command/data buffer is empty. If
* bit-7 is 0, the DSP buffer is empty and is ready to receive commands or
* data. Otherwise, no commands or data should be written to the DSP. */
while ((inp(IO_WRSTAT) & 128) != 0); /* wait for the 'write' buffer to become available */
outp(IO_WRITE, databyte);
}