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ID_SD.C
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//
// ID Engine
// ID_SD.c - Sound Manager for Wolfenstein 3D
// v1.3 (revised for **********, screwed with for Blake Stone)
// By Jason Blochowiak
//
//
// This module handles dealing with generating sound on the appropriate
// hardware
//
// Depends on: User Mgr (for parm checking)
//
// Globals:
// For User Mgr:
// SoundSourcePresent - Sound Source thingie present?
// SoundBlasterPresent - SoundBlaster card present?
// AdLibPresent - AdLib card present?
// SoundMode - What device is used for sound effects
// (Use SM_SetSoundMode() to set)
// MusicMode - What device is used for music
// (Use SM_SetMusicMode() to set)
// DigiMode - What device is used for digitized sound effects
// (Use SM_SetDigiDevice() to set)
//
// For Cache Mgr:
// NeedsDigitized - load digitized sounds?
// NeedsMusic - load music?
//
#pragma hdrstop // Wierdo thing with MUSE
#include <dos.h>
#ifdef _MUSE_ // Will be defined in ID_Types.h
#include "ID_SD.h"
#else
#include "ID_HEADS.H"
#endif
#pragma hdrstop
#pragma warn -pia
#ifdef nil
#undef nil
#endif
#define nil 0
#define SDL_SoundFinished() {SoundNumber = SoundPriority = 0;}
// Macros for SoundBlaster stuff
#define sbOut(n,b) outportb((n) + sbLocation,b)
#define sbIn(n) inportb((n) + sbLocation)
#define sbSimpleWriteDelay() while (sbIn(sbWriteStat) & 0x80);
#define sbReadDelay() while (sbIn(sbDataAvail) & 0x80);
// Macros for AdLib stuff
#define selreg(n) outportb(alFMAddr,n)
#define writereg(n) outportb(alFMData,n)
#define readstat() inportb(alFMStatus)
// Imports from ID_SD_A.ASM
extern void SDL_SetDS(void);
extern void interrupt SDL_t0FastAsmService(void),
SDL_t0SlowAsmService(void);
// Imports from ID_SDD.C
#undef NUMSOUNDS
#undef NUMSNDCHUNKS
#undef STARTPCSOUNDS
#undef STARTADLIBSOUNDS
#undef STARTDIGISOUNDS
#undef STARTMUSIC
extern word sdStartPCSounds;
extern word sdStartALSounds;
extern int sdLastSound;
extern int DigiMap[];
// Global variables
boolean SoundSourcePresent,
AdLibPresent,
SoundBlasterPresent,SBProPresent,
NeedsDigitized,NeedsMusic,
SoundPositioned;
SDMode SoundMode;
SMMode MusicMode;
SDSMode DigiMode;
longword TimeCount;
word HackCount;
word *SoundTable; // Really * _seg *SoundTable, but that don't work
boolean ssIsTandy;
word ssPort = 2;
// Internal variables
static boolean SD_Started;
boolean nextsoundpos;
longword TimerDivisor,TimerCount;
static char far * far ParmStrings[] =
{
"noal",
"nosb",
"nopro",
"noss",
"sst",
"ss1",
"ss2",
"ss3",
nil
};
static void (*SoundUserHook)(void);
soundnames SoundNumber,DigiNumber;
word SoundPriority,DigiPriority;
int LeftPosition,RightPosition;
void interrupt (*t0OldService)(void);
long LocalTime;
word TimerRate;
word NumDigi,DigiLeft,DigiPage;
word _seg *DigiList;
word DigiLastStart,DigiLastEnd;
volatile boolean DigiPlaying;
static volatile boolean DigiMissed,DigiLastSegment;
static volatile memptr DigiNextAddr;
static volatile word DigiNextLen;
volatile longword DigiFailSafe;
longword DigiFailTriggered;
// SoundBlaster variables
word SBResetCount;
static boolean sbNoCheck,sbNoProCheck;
static volatile boolean sbSamplePlaying;
static byte sbPIC1Mask,sbPIC2Mask;
static byte sbOldIntMask = -1,sbOldIntMask2 = -1;
static volatile byte huge *sbNextSegPtr;
static byte sbDMA = 1,
sbDMAa1 = 0x83,sbDMAa2 = 2,sbDMAa3 = 3,
sba1Vals[] = {0x87,0x83,0,0x82},
sba2Vals[] = {0,2,0,6},
sba3Vals[] = {1,3,0,7};
static int sbLocation = -1,sbInterrupt = 7,sbIntVec = 0xf,
sbIntVectors[] = {-1,-1,0xa,0xb,-1,0xd,-1,0xf,-1,-1,0x72};
static volatile byte sbLastTimeValue;
static volatile longword sbNextSegLen;
static volatile SampledSound huge *sbSamples;
static void interrupt (*sbOldIntHand)(void);
static byte sbpOldFMMix,sbpOldVOCMix;
// SoundSource variables
boolean ssNoCheck;
boolean ssActive;
word ssControl,ssStatus,ssData;
byte ssOn,ssOff;
word ssVol;
byte ssVolTable[256];
volatile byte far *ssSample;
volatile longword ssLengthLeft;
// PC Sound variables
volatile byte pcLastSample,far *pcSound;
longword pcLengthLeft;
word pcSoundLookup[255];
// AdLib variables
boolean alNoCheck;
byte far *alSound;
word alBlock;
longword alLengthLeft;
longword alTimeCount;
Instrument alZeroInst;
// This table maps channel numbers to carrier and modulator op cells
static byte carriers[9] = { 3, 4, 5,11,12,13,19,20,21},
modifiers[9] = { 0, 1, 2, 8, 9,10,16,17,18},
// This table maps percussive voice numbers to op cells
pcarriers[5] = {19,0xff,0xff,0xff,0xff},
pmodifiers[5] = {16,17,18,20,21};
// Sequencer variables
boolean sqActive;
static word alFXReg;
static ActiveTrack *tracks[sqMaxTracks],
mytracks[sqMaxTracks];
static word sqMode,sqFadeStep;
word far *sqHack,far *sqHackPtr,sqHackLen,sqHackSeqLen;
long sqHackTime;
boolean sqPlayedOnce;
// Internal routines
void SDL_DigitizedDone(void);
///////////////////////////////////////////////////////////////////////////
//
// SDL_SetTimer0() - Sets system timer 0 to the specified speed
//
///////////////////////////////////////////////////////////////////////////
#pragma argsused
static void
SDL_SetTimer0(word speed)
{
#ifndef TPROF // If using Borland's profiling, don't screw with the timer
asm pushf
asm cli
outportb(0x43,0x36); // Change timer 0
outportb(0x40,speed);
outportb(0x40,speed >> 8);
// Kludge to handle special case for digitized PC sounds
if (TimerDivisor == (1192030 / (TickBase * 100)))
TimerDivisor = (1192030 / (TickBase * 10));
else
TimerDivisor = speed;
asm popf
#else
TimerDivisor = 0x10000;
#endif
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_SetIntsPerSec() - Uses SDL_SetTimer0() to set the number of
// interrupts generated by system timer 0 per second
//
///////////////////////////////////////////////////////////////////////////
static void
SDL_SetIntsPerSec(word ints)
{
TimerRate = ints;
SDL_SetTimer0(1192030 / ints);
}
static void
SDL_SetTimerSpeed(void)
{
word rate;
void interrupt (*isr)(void);
if
(
(MusicMode == smm_AdLib)
|| ((DigiMode == sds_SoundSource) && DigiPlaying)
)
{
rate = TickBase * 10;
isr = SDL_t0FastAsmService;
}
else
{
rate = TickBase * 2;
isr = SDL_t0SlowAsmService;
}
if (rate != TimerRate)
{
setvect(8,isr);
SDL_SetIntsPerSec(rate);
TimerRate = rate;
}
}
//
// SoundBlaster code
//
///////////////////////////////////////////////////////////////////////////
//
// sbWriteDelay() - Waits for the card to become ready. If it doesn't
// become ready, we reset the card, and reprogram the last time value.
//
///////////////////////////////////////////////////////////////////////////
boolean
sbWriteDelay(void)
{
int i;
// Try to avoid hitting the card while it's doing a DMA transfer
for (i = 0;i < 256;i++)
if (sbIn(sbWriteStat) & 0x80)
break;
// See if the DSP is available. If it doesn't go active after 1000
// cycles, assume it hung, and reset the damn thing.
for (i = 0;i < 1000;i++)
if (!(sbIn(sbWriteStat) & 0x80))
break;
if (i == 1000) // Assume that the DSP hung
{
SBResetCount++; // Increment our counter
sbOut(sbReset,true); // Reset the SoundBlaster DSP
for (i = 0;i < 9;i++) // Wait >4usec
inportb(alFMStatus);
sbOut(sbReset,false); // Turn off sb DSP reset
for (i = 0;i < 100;i++) // Wait >100usec
inportb(alFMStatus);
sbSimpleWriteDelay();
sbOut(sbWriteCmd,0xd1); // Turn on DSP speaker
sbSimpleWriteDelay(); // Reprogram last time value
sbOut(sbWriteCmd,0x40);
sbSimpleWriteDelay();
sbOut(sbWriteData,sbLastTimeValue);
return(true);
}
else
return(false);
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_EnableDMAInt() - Save old interrupt status and unmask DMA interrupt
//
///////////////////////////////////////////////////////////////////////////
void
SDL_EnableDMAInt(void)
{
sbOldIntMask = inportb(0x21);
outportb(0x21,sbOldIntMask & ~sbPIC1Mask);
if (sbInterrupt >= 8)
{
sbOldIntMask2 = inportb(0xa1);
outportb(0xa1,sbOldIntMask2 & ~sbPIC2Mask);
}
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_RestoreDMAInt() - Restore DMA interrupt mask bit(s)
//
///////////////////////////////////////////////////////////////////////////
void
SDL_RestoreDMAInt(void)
{
byte is;
is = inportb(0x21);
if (sbOldIntMask & sbPIC1Mask)
is |= sbPIC1Mask;
else
is &= ~sbPIC1Mask;
outportb(0x21,is);
if (sbInterrupt >= 8)
{
is = inportb(0xa1);
if (sbOldIntMask2 & sbPIC2Mask)
is |= sbPIC2Mask;
else
is &= ~sbPIC2Mask;
outportb(0xa1,is);
}
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_SBStopSample() - Stops any active sampled sound and causes DMA
// requests from the SoundBlaster to cease
//
///////////////////////////////////////////////////////////////////////////
#ifdef _MUSE_
void
#else
static void
#endif
SDL_SBStopSample(void)
{
byte is;
int i;
asm pushf
asm cli
if (sbSamplePlaying)
{
sbSamplePlaying = false;
sbWriteDelay();
sbOut(sbWriteCmd,0xd0); // Turn off DSP DMA
for (i = 0;i < 256;i++) // was 80/256
sbIn(sbWriteStat);
#if 0
is = inportb(0x21); // Restore interrupt mask bit
if (sbOldIntMask & (1 << sbInterrupt))
is |= (1 << sbInterrupt);
else
is &= ~(1 << sbInterrupt);
outportb(0x21,is);
#endif
}
asm popf
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_SBPlaySeg() - Plays a chunk of sampled sound on the SoundBlaster
// Insures that the chunk doesn't cross a bank boundary, programs the DMA
// controller, and tells the SB to start doing DMA requests for DAC
//
///////////////////////////////////////////////////////////////////////////
static longword
SDL_SBPlaySeg(volatile byte huge *data,longword length)
{
unsigned datapage;
longword dataofs,uselen;
uselen = length;
datapage = FP_SEG(data) >> 12;
dataofs = ((FP_SEG(data) & 0xfff) << 4) + FP_OFF(data);
if (dataofs >= 0x10000)
{
datapage++;
dataofs -= 0x10000;
}
if (dataofs + uselen > 0x10000)
uselen = 0x10000 - dataofs;
uselen--;
// Program the DMA controller
asm pushf
asm cli
outportb(0x0a,sbDMA | 4); // Mask off DMA on channel sbDMA
outportb(0x0c,0); // Clear byte ptr flip-flop to lower byte
outportb(0x0b,sbDMA | 0x48); // Set transfer mode for D/A conv (Single, address increment, read)
outportb(sbDMAa2,(byte)dataofs); // Give LSB of address
outportb(sbDMAa2,(byte)(dataofs >> 8)); // Give MSB of address
outportb(sbDMAa1,(byte)datapage); // Give page of address
outportb(sbDMAa3,(byte)uselen); // Give LSB of length
outportb(sbDMAa3,(byte)(uselen >> 8)); // Give MSB of length
outportb(0x0a,sbDMA); // Re-enable DMA on channel sbDMA
// Start playing the thing
sbWriteDelay();
sbOut(sbWriteCmd,0x14);
sbWriteDelay();
sbOut(sbWriteData,(byte)uselen);
sbWriteDelay();
sbOut(sbWriteData,(byte)(uselen >> 8));
asm popf
return(uselen + 1);
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_SBService() - Services the SoundBlaster DMA interrupt
//
///////////////////////////////////////////////////////////////////////////
static void interrupt
SDL_SBService(void)
{
longword used;
#if 0 // for debugging
asm mov dx,STATUS_REGISTER_1
asm in al,dx
asm mov dx,ATR_INDEX
asm mov al,ATR_OVERSCAN
asm out dx,al
asm mov al,10 // bright green
asm out dx,al
#endif
sbIn(sbDataAvail); // Ack interrupt to SB
if (sbNextSegPtr)
{
used = SDL_SBPlaySeg(sbNextSegPtr,sbNextSegLen);
if (sbNextSegLen <= used)
sbNextSegPtr = nil;
else
{
sbNextSegPtr += used;
sbNextSegLen -= used;
}
}
else
{
// SDL_SBStopSample();
sbSamplePlaying = false;
SDL_DigitizedDone();
}
outportb(0x20,0x20); // Ack interrupt
if (sbInterrupt >= 8) // If necessary, ack to cascade PIC
outportb(0xa0,0x20);
#if 0 // for debugging
asm mov dx,STATUS_REGISTER_1
asm in al,dx
asm mov dx,ATR_INDEX
asm mov al,ATR_OVERSCAN
asm out dx,al
asm mov al,3 // blue
asm out dx,al
asm mov al,0x20 // normal
asm out dx,al
#endif
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_SBPlaySample() - Plays a sampled sound on the SoundBlaster. Sets up
// DMA to play the sound
//
///////////////////////////////////////////////////////////////////////////
#ifdef _MUSE_
void
#else
static void
#endif
SDL_SBPlaySample(byte huge *data,longword len)
{
longword used;
SDL_SBStopSample();
asm pushf
asm cli
used = SDL_SBPlaySeg(data,len);
if (len <= used)
sbNextSegPtr = nil;
else
{
sbNextSegPtr = data + used;
sbNextSegLen = len - used;
}
#if 0
// Save old interrupt status and unmask ours
sbOldIntMask = inportb(0x21);
outportb(0x21,sbOldIntMask & ~(1 << sbInterrupt));
#endif
#if 0
sbWriteDelay();
sbOut(sbWriteCmd,0xd4); // Make sure DSP DMA is enabled
#endif
sbSamplePlaying = true;
asm popf
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_PositionSBP() - Sets the attenuation levels for the left and right
// channels by using the mixer chip on the SB Pro. This hits a hole in
// the address map for normal SBs.
//
///////////////////////////////////////////////////////////////////////////
static void
SDL_PositionSBP(int leftpos,int rightpos)
{
byte v;
if (!SBProPresent)
return;
leftpos = 15 - leftpos;
rightpos = 15 - rightpos;
v = ((leftpos & 0x0f) << 4) | (rightpos & 0x0f);
asm pushf
asm cli
sbOut(sbpMixerAddr,sbpmVoiceVol);
sbOut(sbpMixerData,v);
asm popf
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_CheckSB() - Checks to see if a SoundBlaster resides at a
// particular I/O location
//
///////////////////////////////////////////////////////////////////////////
static boolean
SDL_CheckSB(int port)
{
int i;
sbLocation = port << 4; // Initialize stuff for later use
sbOut(sbReset,true); // Reset the SoundBlaster DSP
asm mov dx,alFMStatus // Wait >4usec
asm in al, dx
asm in al, dx
asm in al, dx
asm in al, dx
asm in al, dx
asm in al, dx
asm in al, dx
asm in al, dx
asm in al, dx
sbOut(sbReset,false); // Turn off sb DSP reset
asm mov dx,alFMStatus // Wait >100usec
asm mov cx,100
usecloop:
asm in al,dx
asm loop usecloop
for (i = 0;i < 100;i++)
{
if (sbIn(sbDataAvail) & 0x80) // If data is available...
{
if (sbIn(sbReadData) == 0xaa) // If it matches correct value
return(true);
else
{
sbLocation = -1; // Otherwise not a SoundBlaster
return(false);
}
}
}
sbLocation = -1; // Retry count exceeded - fail
return(false);
}
///////////////////////////////////////////////////////////////////////////
//
// Checks to see if a SoundBlaster is in the system. If the port passed is
// -1, then it scans through all possible I/O locations. If the port
// passed is 0, then it uses the default (2). If the port is >0, then
// it just passes it directly to SDL_CheckSB()
//
///////////////////////////////////////////////////////////////////////////
static boolean
SDL_DetectSoundBlaster(int port)
{
int i;
if (port == 0) // If user specifies default, use 2
port = 2;
if (port == -1)
{
if (SDL_CheckSB(2)) // Check default before scanning
return(true);
if (SDL_CheckSB(4)) // Check other SB Pro location before scan
return(true);
for (i = 1;i <= 6;i++) // Scan through possible SB locations
{
if ((i == 2) || (i == 4))
continue;
if (SDL_CheckSB(i)) // If found at this address,
return(true); // return success
}
return(false); // All addresses failed, return failure
}
else
return(SDL_CheckSB(port)); // User specified address or default
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_SBSetDMA() - Sets the DMA channel to be used by the SoundBlaster
// code. Sets up sbDMA, and sbDMAa1-sbDMAa3 (used by SDL_SBPlaySeg()).
//
///////////////////////////////////////////////////////////////////////////
void
SDL_SBSetDMA(byte channel)
{
if (channel > 3)
SD_ERROR(SD_STARTUP_BAD_DMA);
sbDMA = channel;
sbDMAa1 = sba1Vals[channel];
sbDMAa2 = sba2Vals[channel];
sbDMAa3 = sba3Vals[channel];
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_StartSB() - Turns on the SoundBlaster
//
///////////////////////////////////////////////////////////////////////////
static void
SDL_StartSB(void)
{
byte timevalue,test;
sbIntVec = sbIntVectors[sbInterrupt];
if (sbIntVec < 0)
SD_ERROR(SD_STARTUP_BAD_INTERRUPT);
sbPIC1Mask = 1 << (sbInterrupt & 7);
sbPIC2Mask = 1 << 2;
sbOldIntHand = getvect(sbIntVec); // Get old interrupt handler
setvect(sbIntVec,SDL_SBService); // Set mine
SDL_EnableDMAInt(); // Enable DMA interrupt
sbWriteDelay();
sbOut(sbWriteCmd,0xd1); // Turn on DSP speaker
// Set the SoundBlaster DAC time constant for 7KHz
timevalue = 256 - (1000000 / 7000);
sbLastTimeValue = timevalue;
sbWriteDelay();
sbOut(sbWriteCmd,0x40);
sbWriteDelay();
sbOut(sbWriteData,timevalue);
SBProPresent = false;
if (sbNoProCheck)
return;
// Check to see if this is a SB Pro
sbOut(sbpMixerAddr,sbpmFMVol);
sbpOldFMMix = sbIn(sbpMixerData);
sbOut(sbpMixerData,0xbb);
test = sbIn(sbpMixerData);
if (test == 0xbb)
{
// Boost FM output levels to be equivilent with digitized output
sbOut(sbpMixerData,0xff);
test = sbIn(sbpMixerData);
if (test == 0xff)
{
SBProPresent = true;
// Save old Voice output levels (SB Pro)
sbOut(sbpMixerAddr,sbpmVoiceVol);
sbpOldVOCMix = sbIn(sbpMixerData);
// Turn SB Pro stereo DAC off
sbOut(sbpMixerAddr,sbpmControl);
sbOut(sbpMixerData,0); // 0=off,2=on
}
}
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_ShutSB() - Turns off the SoundBlaster
//
///////////////////////////////////////////////////////////////////////////
static void
SDL_ShutSB(void)
{
SDL_SBStopSample();
SDL_RestoreDMAInt(); // Restore DMA interrupt
if (SBProPresent)
{
// Restore FM output levels (SB Pro)
sbOut(sbpMixerAddr,sbpmFMVol);
sbOut(sbpMixerData,sbpOldFMMix);
// Restore Voice output levels (SB Pro)
sbOut(sbpMixerAddr,sbpmVoiceVol);
sbOut(sbpMixerData,sbpOldVOCMix);
}
setvect(sbIntVec,sbOldIntHand); // Set vector back
}
// Sound Source Code
void
SDL_SSSetVol(word vol)
{
int i;
long v;
if (vol == ssVol)
return;
ssVol = vol;
#if 1
v = vol * -128;
for (i = 0;i < 256;i++)
{
ssVolTable[i] = (v >> 8) + 0x80;
v += vol;
}
#else
for (i = 0;i < 256;i++)
ssVolTable[i] = (((i - 0x80) * vol) >> 8) + 0x80;
#endif
}
static void
SDL_PositionSS(int leftpos,int rightpos)
{
int pos;
pos = (leftpos > rightpos)? rightpos : leftpos;
pos = 15 - pos;
pos *= 17;
SDL_SSSetVol(pos);
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_SSStopSample() - Stops a sample playing on the Sound Source
//
///////////////////////////////////////////////////////////////////////////
#ifdef _MUSE_
void
#else
static void
#endif
SDL_SSStopSample(void)
{
asm pushf
asm cli
(long)ssSample = 0;
asm popf
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_SSService() - Handles playing the next sample on the Sound Source
//
///////////////////////////////////////////////////////////////////////////
static void
SDL_SSService(void)
{
boolean gotit;
byte v;
while (ssSample)
{
asm mov dx,[ssStatus] // Check to see if FIFO is currently empty
asm in al,dx
asm test al,0x40
asm jnz done // Nope - don't push any more data out
v = *ssSample++;
v = ssVolTable[v];
if (!(--ssLengthLeft))
{
(long)ssSample = 0;
SDL_DigitizedDone();
}
asm mov dx,[ssData] // Pump the value out
asm mov al,[v]
asm out dx,al
asm mov dx,[ssControl] // Pulse printer select
asm mov al,[ssOff]
asm out dx,al
asm push ax
asm pop ax
asm mov al,[ssOn]
asm out dx,al
asm push ax // Delay a short while
asm pop ax
asm push ax
asm pop ax
}
done:;
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_SSPlaySample() - Plays the specified sample on the Sound Source
//
///////////////////////////////////////////////////////////////////////////
#ifdef _MUSE_
void
#else
static void
#endif
SDL_SSPlaySample(byte huge *data,longword len)
{
asm pushf
asm cli
ssLengthLeft = len;
ssSample = (volatile byte far *)data;
asm popf
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_StartSS() - Sets up for and turns on the Sound Source
//
///////////////////////////////////////////////////////////////////////////
static void
SDL_StartSS(void)
{
if (ssPort == 3)
ssControl = 0x27a; // If using LPT3
else if (ssPort == 2)
ssControl = 0x37a; // If using LPT2
else
ssControl = 0x3be; // If using LPT1
ssStatus = ssControl - 1;
ssData = ssStatus - 1;
ssOn = 0x04;
if (ssIsTandy)
ssOff = 0x0e; // Tandy wierdness
else
ssOff = 0x0c; // For normal machines
outportb(ssControl,ssOn); // Enable SS
SDL_SSSetVol(0x100);
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_ShutSS() - Turns off the Sound Source
//
///////////////////////////////////////////////////////////////////////////
static void
SDL_ShutSS(void)
{
outportb(ssControl,ssOff);
}
///////////////////////////////////////////////////////////////////////////
//
// SDL_CheckSS() - Checks to see if a Sound Source is present at the
// location specified by the sound source variables
//
///////////////////////////////////////////////////////////////////////////
static boolean
SDL_CheckSS(void)
{
boolean present = false;
longword lasttime;
// Turn the Sound Source on and wait awhile (4 ticks)
SDL_StartSS();
lasttime = TimeCount;
while (TimeCount < lasttime + 4)
;
asm mov dx,[ssStatus] // Check to see if FIFO is currently empty
asm in al,dx
asm test al,0x40
asm jnz checkdone // Nope - Sound Source not here
asm mov cx,32 // Force FIFO overflow (FIFO is 16 bytes)
outloop:
asm mov dx,[ssData] // Pump a neutral value out
asm mov al,0x80
asm out dx,al
asm mov dx,[ssControl] // Pulse printer select
asm mov al,[ssOff]
asm out dx,al
asm push ax
asm pop ax
asm mov al,[ssOn]
asm out dx,al
asm push ax // Delay a short while before we do this again
asm pop ax
asm push ax
asm pop ax
asm loop outloop
asm mov dx,[ssStatus] // Is FIFO overflowed now?
asm in al,dx
asm test al,0x40
asm jz checkdone // Nope, still not - Sound Source not here
present = true; // Yes - it's here!
checkdone:
SDL_ShutSS();
return(present);
}
static boolean
SDL_DetectSoundSource(void)
{
for (ssPort = 1;ssPort <= 3;ssPort++)
if (SDL_CheckSS())
return(true);
return(false);
}