snd_dma.c

quakeIII源码这个不用我多说吧

	if (entityNum == listener_number) {
		allowed = 8;
	}

	ch = s_channels;
	inplay = 0;
	for ( i = 0; i < MAX_CHANNELS ; i++, ch++ ) {		
		if (ch[i].entnum == entityNum && ch[i].thesfx == sfx) {
			if (time - ch[i].allocTime < 50) {
//				if (Cvar_VariableValue( "cg_showmiss" )) {
//					Com_Printf("double sound start\n");
//				}
				return;
			}
			inplay++;
		}
	}

	if (inplay>allowed) {
		return;
	}

	sfx->lastTimeUsed = time;

	ch = S_ChannelMalloc();	// entityNum, entchannel);
	if (!ch) {
		ch = s_channels;

		oldest = sfx->lastTimeUsed;
		chosen = -1;
		for ( i = 0 ; i < MAX_CHANNELS ; i++, ch++ ) {
			if (ch->entnum != listener_number && ch->entnum == entityNum && ch->allocTime<oldest && ch->entchannel != CHAN_ANNOUNCER) {
				oldest = ch->allocTime;
				chosen = i;
			}
		}
		if (chosen == -1) {
			ch = s_channels;
			for ( i = 0 ; i < MAX_CHANNELS ; i++, ch++ ) {
				if (ch->entnum != listener_number && ch->allocTime<oldest && ch->entchannel != CHAN_ANNOUNCER) {
					oldest = ch->allocTime;
					chosen = i;
				}
			}
			if (chosen == -1) {
				if (ch->entnum == listener_number) {
					for ( i = 0 ; i < MAX_CHANNELS ; i++, ch++ ) {
						if (ch->allocTime<oldest) {
							oldest = ch->allocTime;
							chosen = i;
						}
					}
				}
				if (chosen == -1) {
					Com_Printf("dropping sound\n");
					return;
				}
			}
		}
		ch = &s_channels[chosen];
		ch->allocTime = sfx->lastTimeUsed;
	}

	if (origin) {
		VectorCopy (origin, ch->origin);
		ch->fixed_origin = qtrue;
	} else {
		ch->fixed_origin = qfalse;
	}

	ch->master_vol = 127;
	ch->entnum = entityNum;
	ch->thesfx = sfx;
	ch->startSample = START_SAMPLE_IMMEDIATE;
	ch->entchannel = entchannel;
	ch->leftvol = ch->master_vol;		// these will get calced at next spatialize
	ch->rightvol = ch->master_vol;		// unless the game isn't running
	ch->doppler = qfalse;
}


/*
==================
S_StartLocalSound
==================
*/
void S_StartLocalSound( sfxHandle_t sfxHandle, int channelNum ) {
	if ( !s_soundStarted || s_soundMuted ) {
		return;
	}

	if ( sfxHandle < 0 || sfxHandle >= s_numSfx ) {
		Com_Printf( S_COLOR_YELLOW, "S_StartLocalSound: handle %i out of range\n", sfxHandle );
		return;
	}

	S_StartSound (NULL, listener_number, channelNum, sfxHandle );
}


/*
==================
S_ClearSoundBuffer

If we are about to perform file access, clear the buffer
so sound doesn't stutter.
==================
*/
void S_ClearSoundBuffer( void ) {
	int		clear;
		
	if (!s_soundStarted)
		return;

	// stop looping sounds
	Com_Memset(loopSounds, 0, MAX_GENTITIES*sizeof(loopSound_t));
	Com_Memset(loop_channels, 0, MAX_CHANNELS*sizeof(channel_t));
	numLoopChannels = 0;

	S_ChannelSetup();

	s_rawend = 0;

	if (dma.samplebits == 8)
		clear = 0x80;
	else
		clear = 0;

	SNDDMA_BeginPainting ();
	if (dma.buffer)
    // TTimo: due to a particular bug workaround in linux sound code,
    //   have to optionally use a custom C implementation of Com_Memset
    //   not affecting win32, we have #define Snd_Memset Com_Memset
    // https://zerowing.idsoftware.com/bugzilla/show_bug.cgi?id=371
		Snd_Memset(dma.buffer, clear, dma.samples * dma.samplebits/8);
	SNDDMA_Submit ();
}

/*
==================
S_StopAllSounds
==================
*/
void S_StopAllSounds(void) {
	if ( !s_soundStarted ) {
		return;
	}

	// stop the background music
	S_StopBackgroundTrack();

	S_ClearSoundBuffer ();
}

/*
==============================================================

continuous looping sounds are added each frame

==============================================================
*/

void S_StopLoopingSound(int entityNum) {
	loopSounds[entityNum].active = qfalse;
//	loopSounds[entityNum].sfx = 0;
	loopSounds[entityNum].kill = qfalse;
}

/*
==================
S_ClearLoopingSounds

==================
*/
void S_ClearLoopingSounds( qboolean killall ) {
	int i;
	for ( i = 0 ; i < MAX_GENTITIES ; i++) {
		if (killall || loopSounds[i].kill == qtrue || (loopSounds[i].sfx && loopSounds[i].sfx->soundLength == 0)) {
			loopSounds[i].kill = qfalse;
			S_StopLoopingSound(i);
		}
	}
	numLoopChannels = 0;
}

/*
==================
S_AddLoopingSound

Called during entity generation for a frame
Include velocity in case I get around to doing doppler...
==================
*/
void S_AddLoopingSound( int entityNum, const vec3_t origin, const vec3_t velocity, sfxHandle_t sfxHandle ) {
	sfx_t *sfx;

	if ( !s_soundStarted || s_soundMuted ) {
		return;
	}

	if ( sfxHandle < 0 || sfxHandle >= s_numSfx ) {
		Com_Printf( S_COLOR_YELLOW, "S_AddLoopingSound: handle %i out of range\n", sfxHandle );
		return;
	}

	sfx = &s_knownSfx[ sfxHandle ];

	if (sfx->inMemory == qfalse) {
		S_memoryLoad(sfx);
	}

	if ( !sfx->soundLength ) {
		Com_Error( ERR_DROP, "%s has length 0", sfx->soundName );
	}

	VectorCopy( origin, loopSounds[entityNum].origin );
	VectorCopy( velocity, loopSounds[entityNum].velocity );
	loopSounds[entityNum].active = qtrue;
	loopSounds[entityNum].kill = qtrue;
	loopSounds[entityNum].doppler = qfalse;
	loopSounds[entityNum].oldDopplerScale = 1.0;
	loopSounds[entityNum].dopplerScale = 1.0;
	loopSounds[entityNum].sfx = sfx;

	if (s_doppler->integer && VectorLengthSquared(velocity)>0.0) {
		vec3_t	out;
		float	lena, lenb;

		loopSounds[entityNum].doppler = qtrue;
		lena = DistanceSquared(loopSounds[listener_number].origin, loopSounds[entityNum].origin);
		VectorAdd(loopSounds[entityNum].origin, loopSounds[entityNum].velocity, out);
		lenb = DistanceSquared(loopSounds[listener_number].origin, out);
		if ((loopSounds[entityNum].framenum+1) != cls.framecount) {
			loopSounds[entityNum].oldDopplerScale = 1.0;
		} else {
			loopSounds[entityNum].oldDopplerScale = loopSounds[entityNum].dopplerScale;
		}
		loopSounds[entityNum].dopplerScale = lenb/(lena*100);
		if (loopSounds[entityNum].dopplerScale<=1.0) {
			loopSounds[entityNum].doppler = qfalse;			// don't bother doing the math
		}
	}

	loopSounds[entityNum].framenum = cls.framecount;
}

/*
==================
S_AddLoopingSound

Called during entity generation for a frame
Include velocity in case I get around to doing doppler...
==================
*/
void S_AddRealLoopingSound( int entityNum, const vec3_t origin, const vec3_t velocity, sfxHandle_t sfxHandle ) {
	sfx_t *sfx;

	if ( !s_soundStarted || s_soundMuted ) {
		return;
	}

	if ( sfxHandle < 0 || sfxHandle >= s_numSfx ) {
		Com_Printf( S_COLOR_YELLOW, "S_AddRealLoopingSound: handle %i out of range\n", sfxHandle );
		return;
	}

	sfx = &s_knownSfx[ sfxHandle ];

	if (sfx->inMemory == qfalse) {
		S_memoryLoad(sfx);
	}

	if ( !sfx->soundLength ) {
		Com_Error( ERR_DROP, "%s has length 0", sfx->soundName );
	}
	VectorCopy( origin, loopSounds[entityNum].origin );
	VectorCopy( velocity, loopSounds[entityNum].velocity );
	loopSounds[entityNum].sfx = sfx;
	loopSounds[entityNum].active = qtrue;
	loopSounds[entityNum].kill = qfalse;
	loopSounds[entityNum].doppler = qfalse;
}



/*
==================
S_AddLoopSounds

Spatialize all of the looping sounds.
All sounds are on the same cycle, so any duplicates can just
sum up the channel multipliers.
==================
*/
void S_AddLoopSounds (void) {
	int			i, j, time;
	int			left_total, right_total, left, right;
	channel_t	*ch;
	loopSound_t	*loop, *loop2;
	static int	loopFrame;


	numLoopChannels = 0;

	time = Com_Milliseconds();

	loopFrame++;
	for ( i = 0 ; i < MAX_GENTITIES ; i++) {
		loop = &loopSounds[i];
		if ( !loop->active || loop->mergeFrame == loopFrame ) {
			continue;	// already merged into an earlier sound
		}

		if (loop->kill) {
			S_SpatializeOrigin( loop->origin, 127, &left_total, &right_total);			// 3d
		} else {
			S_SpatializeOrigin( loop->origin, 90,  &left_total, &right_total);			// sphere
		}

		loop->sfx->lastTimeUsed = time;

		for (j=(i+1); j< MAX_GENTITIES ; j++) {
			loop2 = &loopSounds[j];
			if ( !loop2->active || loop2->doppler || loop2->sfx != loop->sfx) {
				continue;
			}
			loop2->mergeFrame = loopFrame;

			if (loop2->kill) {
				S_SpatializeOrigin( loop2->origin, 127, &left, &right);				// 3d
			} else {
				S_SpatializeOrigin( loop2->origin, 90,  &left, &right);				// sphere
			}

			loop2->sfx->lastTimeUsed = time;
			left_total += left;
			right_total += right;
		}
		if (left_total == 0 && right_total == 0) {
			continue;		// not audible
		}

		// allocate a channel
		ch = &loop_channels[numLoopChannels];
		
		if (left_total > 255) {
			left_total = 255;
		}
		if (right_total > 255) {
			right_total = 255;
		}
		
		ch->master_vol = 127;
		ch->leftvol = left_total;
		ch->rightvol = right_total;
		ch->thesfx = loop->sfx;
		ch->doppler = loop->doppler;
		ch->dopplerScale = loop->dopplerScale;
		ch->oldDopplerScale = loop->oldDopplerScale;
		numLoopChannels++;
		if (numLoopChannels == MAX_CHANNELS) {
			return;
		}
	}
}

//=============================================================================

/*
=================
S_ByteSwapRawSamples

If raw data has been loaded in little endien binary form, this must be done.
If raw data was calculated, as with ADPCM, this should not be called.
=================
*/
void S_ByteSwapRawSamples( int samples, int width, int s_channels, const byte *data ) {
	int		i;

	if ( width != 2 ) {
		return;
	}
	if ( LittleShort( 256 ) == 256 ) {
		return;
	}

	if ( s_channels == 2 ) {
		samples <<= 1;
	}
	for ( i = 0 ; i < samples ; i++ ) {
		((short *)data)[i] = LittleShort( ((short *)data)[i] );
	}
}

portable_samplepair_t *S_GetRawSamplePointer() {
	return s_rawsamples;
}

/*
============
S_RawSamples

Music streaming
============
*/
void S_RawSamples( int samples, int rate, int width, int s_channels, const byte *data, float volume ) {
	int		i;
	int		src, dst;
	float	scale;
	int		intVolume;

	if ( !s_soundStarted || s_soundMuted ) {
		return;
	}

	intVolume = 256 * volume;

	if ( s_rawend < s_soundtime ) {
		Com_DPrintf( "S_RawSamples: resetting minimum: %i < %i\n", s_rawend, s_soundtime );
		s_rawend = s_soundtime;
	}

	scale = (float)rate / dma.speed;

//Com_Printf ("%i < %i < %i\n", s_soundtime, s_paintedtime, s_rawend);
	if (s_channels == 2 && width == 2)
	{
		if (scale == 1.0)
		{	// optimized case
			for (i=0 ; i<samples ; i++)
			{
				dst = s_rawend&(MAX_RAW_SAMPLES-1);
				s_rawend++;
				s_rawsamples[dst].left = ((short *)data)[i*2] * intVolume;
				s_rawsamples[dst].right = ((short *)data)[i*2+1] * intVolume;
			}
		}
		else
		{
			for (i=0 ; ; i++)
			{
				src = i*scale;
				if (src >= samples)
					break;
				dst = s_rawend&(MAX_RAW_SAMPLES-1);
				s_rawend++;
				s_rawsamples[dst].left = ((short *)data)[src*2] * intVolume;
				s_rawsamples[dst].right = ((short *)data)[src*2+1] * intVolume;
			}
		}
	}
	else if (s_channels == 1 && width == 2)
	{
		for (i=0 ; ; i++)
		{
			src = i*scale;
			if (src >= samples)
				break;
			dst = s_rawend&(MAX_RAW_SAMPLES-1);
			s_rawend++;
			s_rawsamples[dst].left = ((short *)data)[src] * intVolume;
			s_rawsamples[dst].right = ((short *)data)[src] * intVolume;
		}
	}
	else if (s_channels == 2 && width == 1)
	{
		intVolume *= 256;

		for (i=0 ; ; i++)
		{
			src = i*scale;
			if (src >= samples)
				break;
			dst = s_rawend&(MAX_RAW_SAMPLES-1);
			s_rawend++;
			s_rawsamples[dst].left = ((char *)data)[src*2] * intVolume;
			s_rawsamples[dst].right = ((char *)data)[src*2+1] * intVolume;
		}
	}
	else if (s_channels == 1 && width == 1)
	{
		intVolume *= 256;

		for (i=0 ; ; i++)
		{
			src = i*scale;
			if (src >= samples)
				break;
			dst = s_rawend&(MAX_RAW_SAMPLES-1);
			s_rawend++;
			s_rawsamples[dst].left = (((byte *)data)[src]-128) * intVolume;
			s_rawsamples[dst].right = (((byte *)data)[src]-128) * intVolume;
		}
	}

	if ( s_rawend > s_soundtime + MAX_RAW_SAMPLES ) {
		Com_DPrintf( "S_RawSamples: overflowed %i > %i\n", s_rawend, s_soundtime );
	}
}

//=============================================================================

/*
=====================
S_UpdateEntityPosition

let the sound system know where an entity currently is
======================
*/
void S_UpdateEntityPosition( int entityNum, const vec3_t origin ) {
	if ( entityNum < 0 || entityNum > MAX_GENTITIES ) {
		Com_Error( ERR_DROP, "S_UpdateEntityPosition: bad entitynum %i", entityNum );
	}
	VectorCopy( origin, loopSounds[entityNum].origin );
}


/*
============
S_Respatialize

Change the volumes of all the playing sounds for changes in their positions
============
*/
void S_Respatialize( int entityNum, const vec3_t head, vec3_t axis[3], int inwater ) {
	int			i;
	channel_t	*ch;
	vec3_t		origin;

	if ( !s_soundStarted || s_soundMuted ) {
		return;
	}

	listener_number = entityNum;
	VectorCopy(head, listener_origin);
	VectorCopy(axis[0], listener_axis[0]);
	VectorCopy(axis[1], listener_axis[1]);
	VectorCopy(axis[2], listener_axis[2]);

	// update spatialization for dynamic sounds	
	ch = s_channels;
	for ( i = 0 ; i < MAX_CHANNELS ; i++, ch++ ) {
		if ( !ch->thesfx ) {
			continue;
		}
		// anything coming from the view entity will always be full volume