Xash3D FWGS engine.
 
 
 
 

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/*
s_utils.c - common sound functions
Copyright (C) 2009 Uncle Mike
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
*/
#include "common.h"
#include "sound.h"
// hardcoded macros to test for zero crossing
#define ZERO_X_8( b ) (( b ) < 2 && ( b ) > -2 )
#define ZERO_X_16( b ) (( b ) < 512 && ( b ) > -512 )
//-----------------------------------------------------------------------------
// Purpose: Search backward for a zero crossing starting at sample
// Input : sample - starting point
// Output : position of zero crossing
//-----------------------------------------------------------------------------
int S_ZeroCrossingBefore( wavdata_t *pWaveData, int sample )
{
if( pWaveData == NULL )
return sample;
if( pWaveData->type == WF_PCMDATA )
{
int sampleSize;
sampleSize = pWaveData->width * pWaveData->channels;
// this can never be zero -- other functions divide by this.
// This should never happen, but avoid crashing
if( sampleSize <= 0 ) sampleSize = 1;
if( pWaveData->width == 1 )
{
signed char *pData = (signed char *)(pWaveData->buffer + sample * sampleSize);
qboolean zero = false;
if( pWaveData->channels == 1 )
{
while( sample > 0 && !zero )
{
if( ZERO_X_8( *pData ))
{
zero = true;
}
else
{
sample--;
pData--;
}
}
}
else
{
while( sample > 0 && !zero )
{
if( ZERO_X_8( *pData ) && ZERO_X_8( pData[1] ))
{
zero = true;
}
else
{
sample--;
pData--;
}
}
}
}
else
{
short *pData = (short *)(pWaveData->buffer + sample * sampleSize);
qboolean zero = false;
if( pWaveData->channels == 1 )
{
while( sample > 0 && !zero )
{
if( ZERO_X_16(*pData ))
{
zero = true;
}
else
{
pData--;
sample--;
}
}
}
else
{
while( sample > 0 && !zero )
{
if( ZERO_X_16( *pData ) && ZERO_X_16( pData[1] ))
{
zero = true;
}
else
{
sample--;
pData--;
}
}
}
}
}
return sample;
}
//-----------------------------------------------------------------------------
// Purpose: Search forward for a zero crossing
// Input : sample - starting point
// Output : position of found zero crossing
//-----------------------------------------------------------------------------
int S_ZeroCrossingAfter( wavdata_t *pWaveData, int sample )
{
if( pWaveData == NULL )
return sample;
if( pWaveData->type == WF_PCMDATA )
{
int sampleSize;
sampleSize = pWaveData->width * pWaveData->channels;
// this can never be zero -- other functions divide by this.
// This should never happen, but avoid crashing
if( sampleSize <= 0 ) sampleSize = 1;
if( pWaveData->width == 1 ) // 8-bit
{
signed char *pData = (signed char *)(pWaveData->buffer + sample * sampleSize);
qboolean zero = false;
if( pWaveData->channels == 1 )
{
while( sample < pWaveData->samples && !zero )
{
if( ZERO_X_8( *pData ))
{
zero = true;
}
else
{
sample++;
pData++;
}
}
}
else
{
while( sample < pWaveData->samples && !zero )
{
if( ZERO_X_8( *pData ) && ZERO_X_8( pData[1] ))
{
zero = true;
}
else
{
sample++;
pData++;
}
}
}
}
else
{
short *pData = (short *)(pWaveData->buffer + sample * sampleSize);
qboolean zero = false;
if( pWaveData->channels == 1 )
{
while( sample > 0 && !zero )
{
if( ZERO_X_16( *pData ))
{
zero = true;
}
else
{
pData++;
sample++;
}
}
}
else
{
while( sample > 0 && !zero )
{
if( ZERO_X_16( *pData ) && ZERO_X_16( pData[1] ))
{
zero = true;
}
else
{
sample++;
pData++;
}
}
}
}
}
return sample;
}
//-----------------------------------------------------------------------------
// Purpose: wrap the position wrt looping
// Input : samplePosition - absolute position
// Output : int - looped position
//-----------------------------------------------------------------------------
int S_ConvertLoopedPosition( wavdata_t *pSource, int samplePosition, qboolean use_loop )
{
// if the wave is looping and we're past the end of the sample
// convert to a position within the loop
// At the end of the loop, we return a short buffer, and subsequent call
// will loop back and get the rest of the buffer
if( pSource->loopStart >= 0 && samplePosition >= pSource->samples && use_loop )
{
// size of loop
int loopSize = pSource->samples - pSource->loopStart;
// subtract off starting bit of the wave
samplePosition -= pSource->loopStart;
if( loopSize )
{
// "real" position in memory (mod off extra loops)
samplePosition = pSource->loopStart + ( samplePosition % loopSize );
}
// ERROR? if no loopSize
}
return samplePosition;
}
int S_GetOutputData( wavdata_t *pSource, void **pData, int samplePosition, int sampleCount, qboolean use_loop )
{
int totalSampleCount;
int sampleSize;
// handle position looping
samplePosition = S_ConvertLoopedPosition( pSource, samplePosition, use_loop );
// how many samples are available (linearly not counting looping)
totalSampleCount = pSource->samples - samplePosition;
// may be asking for a sample out of range, clip at zero
if( totalSampleCount < 0 ) totalSampleCount = 0;
// clip max output samples to max available
if( sampleCount > totalSampleCount )
sampleCount = totalSampleCount;
sampleSize = pSource->width * pSource->channels;
// this can never be zero -- other functions divide by this.
// This should never happen, but avoid crashing
if( sampleSize <= 0 ) sampleSize = 1;
// byte offset in sample database
samplePosition *= sampleSize;
// if we are returning some samples, store the pointer
if( sampleCount )
{
*pData = pSource->buffer + samplePosition;
}
return sampleCount;
}
// move the current position to newPosition
void S_SetSampleStart( channel_t *pChan, wavdata_t *pSource, int newPosition )
{
if( pSource )
newPosition = S_ZeroCrossingAfter( pSource, newPosition );
pChan->pMixer.sample = newPosition;
}
// end playback at newEndPosition
void S_SetSampleEnd( channel_t *pChan, wavdata_t *pSource, int newEndPosition )
{
// forced end of zero means play the whole sample
if( !newEndPosition ) newEndPosition = 1;
if( pSource )
newEndPosition = S_ZeroCrossingBefore( pSource, newEndPosition );
// past current position? limit.
if( newEndPosition < pChan->pMixer.sample )
newEndPosition = pChan->pMixer.sample;
pChan->pMixer.forcedEndSample = newEndPosition;
}