sound.cpp

/*
 *  sound.c
 *  Allenroids
 *
 *  Provides sound playback via SDL.
 *
 */

#include "sound.h"
#include "Allenroids.h"

boolean audioOn;

SoundSample channels[NUMBER_CHANNELS];

char *soundName[]=
{								//soundBuffer Index:
	"Sounds/Pop.wav",				//	0
	"Sounds/PopAlien.wav",			//	1
	"Sounds/Shields.wav",			//	2
	"Sounds/Thrust.wav",			//	3
	"Sounds/StopThrusting.wav",		//	4
	"Sounds/ExplosionSmall.wav",	//	5
	"Sounds/ExplosionMedium.wav",	//	6
	"Sounds/ExplosionLarge.wav",	//	7
	"Sounds/ExplosionHuge.wav",		//	8
	"Sounds/WarningPlayer1.wav",	//	9
	"Sounds/WarningPlayer2.wav",	//	10
	"Sounds/ReleaseCrystal.wav",	//	11
	"Sounds/RetrieveCrystal.wav",	//	12
	"Sounds/CrystalSplatter.wav",	//	13
	"Sounds/WarningAlien.wav",		//	14
	"Sounds/ShotTunk.wav"			//  15
};

SDL_AudioCVT soundBuffer[NUMBER_SOUNDS];

/****************************************************
 * soundInit
 *  set up SDL sound
 ***************************************************/
void soundInit(){

	SDL_AudioSpec soundFormat;
	
    /* Set 16-bit stereo audio at 22Khz */
    soundFormat.freq = 22050;
//    soundFormat.freq = 11127;
    soundFormat.format = AUDIO_S16;
    soundFormat.channels = 2; // 1 = mono, 2 = stereo
    soundFormat.samples = 1024; // A good value for games
    soundFormat.callback = mixaudio; //a function!
    soundFormat.userdata = NULL;
	
	if( SDL_OpenAudio(&soundFormat, NULL) < 0) {
		//printf("Warning: %s\n", SDL_GetError());
		audioOn = false;
		return;
	}
	else
		audioOn = true;
	
	loadSounds(soundName, soundBuffer, NUMBER_SOUNDS);
	
	SDL_PauseAudio(false); //activate sound
	//load all the sounds here
}


/****************************************************
 * loadSounds
 *  copies the specified sound names to memory
 ***************************************************/
void loadSounds(char *nameBuffer[], SDL_AudioCVT soundBuffer[], unsigned int numberSounds){
	unsigned int counter;
    SDL_AudioSpec wave;
    Uint8 *data;
    Uint32 dataLength;	
	
	for(counter = 0; counter < numberSounds; counter++){
		// Load the sound file and convert it to 16-bit stereo at 22kHz
		if ( SDL_LoadWAV(nameBuffer[counter], &wave, &data, &dataLength) == NULL ) {
			//fprintf(stderr, "Couldn't load %s: %s\n", nameBuffer[counter], SDL_GetError());
			return;
		}
		SDL_BuildAudioCVT(&soundBuffer[counter],
				wave.format,	wave.channels,	wave.freq,
				AUDIO_S16,		2,				22050);
		soundBuffer[counter].buf = (Uint8 *) malloc(dataLength * soundBuffer[counter].len_mult);
		memcpy(soundBuffer[counter].buf, data, dataLength);
		soundBuffer[counter].len = dataLength;
		SDL_ConvertAudio(&soundBuffer[counter]);
		SDL_FreeWAV(data);
	}//end for

}

/****************************************************
 * mixAudio
 *  plays all the sounds on the docket at once.
 ***************************************************/
void mixaudio(void *unused, Uint8 *stream, int length)
{
    unsigned int counter;
    //Uint32 amount; //as suggested by tutorial code; creates signed/unsigned complaints
	int amount;
	
    for ( counter = 0; counter < NUMBER_CHANNELS; counter++ ){
		amount = (channels[counter].dataLength - channels[counter].dataPosition);
		if ( amount > length ){
			amount = length;
		}
		SDL_MixAudio(stream, &channels[counter].data[channels[counter].dataPosition], amount, SDL_MIX_MAXVOLUME);
		channels[counter].dataPosition += amount;
    }
}


/****************************************************
 * playSound
 *  run a sound
 *	adapted from http://www.libsdl.org/intro/usingsound.html
 ***************************************************/
void playSound(SDL_AudioCVT soundList[], int idToPlay){
    int index;

    // Look for an empty (or finished) sound slot
    for ( index = 0; index < NUMBER_CHANNELS; ++index ) {
        if ( channels[index].dataPosition == channels[index].dataLength ) {
			//a finished sound has been found (position = length)
            break;
        }
    }
    if ( index == NUMBER_CHANNELS )
        return; //no slot found
	
    // Put the sound data in the slot (it starts playing immediately)
    SDL_LockAudio();
		channels[index].data = soundList[idToPlay].buf;
		channels[index].dataLength = soundList[idToPlay].len_cvt;
		channels[index].dataPosition = 0;
		channels[index].soundID = idToPlay;
    SDL_UnlockAudio();
}