fceugx/source/ngc/gcaudio.c

/****************************************************************************
 * FCE Ultra 0.98.12
 * Nintendo Wii/Gamecube Port
 *
 * Tantric September 2008
 *
 * audio.c
 *
 * Audio driver
 ****************************************************************************/

#include <gccore.h>
#include <string.h>

#define SAMPLERATE 48000
unsigned char audiobuffer[2][64 * 1024] ATTRIBUTE_ALIGN(32);
/*** Allow for up to 1 full second ***/

/****************************************************************************
 * AudioSwitchBuffers
 *
 * Manages which buffer is played next
 ****************************************************************************/
static int isWriting = 0;	/*** Bool for buffer writes ***/
static int buffSize[2];		/*** Hold size of current buffer ***/
static int whichab = 0;		/*** Which Audio Buffer is in use ***/
static int isPlaying;		/*** Is Playing ***/
static void AudioSwitchBuffers()
{
	if ( buffSize[whichab] )
	{
		AUDIO_StopDMA();
		AUDIO_InitDMA((u32)audiobuffer[whichab], buffSize[whichab]);
		DCFlushRange(audiobuffer[whichab], buffSize[whichab]);
		AUDIO_StartDMA();
		isPlaying = 0;
	}

	whichab ^= 1;
	buffSize[whichab] = 0;
}

void InitialiseSound()
{
	AUDIO_Init(NULL);	/*** Start audio subsystem ***/
	AUDIO_SetDSPSampleRate(AI_SAMPLERATE_48KHZ);
	AUDIO_RegisterDMACallback( AudioSwitchBuffers );
	memset(audiobuffer, 0, (64 * 1024 * 2));
	buffSize[0] = buffSize[1] = 0;
}

void StartAudio()
{
	AUDIO_StartDMA();
}

void StopAudio()
{
	AUDIO_StopDMA();
	buffSize[0] = buffSize[1] = 0;
}

static inline unsigned short FLIP16(unsigned short b)
{
	return((b<<8)|((b>>8)&0xFF));
}

static inline u32 FLIP32(u32 b)
{
	return( (b<<24) | ((b>>8)&0xFF00) | ((b<<8)&0xFF0000) | ((b>>24)&0xFF) );
}

/****************************************************************************
 * Audio incoming is monaural
 *
 * PlaySound will simply mix to get it right
 ****************************************************************************/
#define AUDIOBUFFER ((50 * SAMPLERATE) / 1000 ) << 4
static int isPlaying = 0;
static short MBuffer[ 8 * 96000 / 50 ];

void PlaySound( unsigned int *Buffer, int count )
{
	int P;
	unsigned short *s = (unsigned short *)&MBuffer[0];
	unsigned int *d = (unsigned int *)&audiobuffer[whichab][buffSize[whichab]];
	unsigned int c;
	int ms;

	isWriting = 1;

	for ( P = 0; P < count; P++ )
	{
		MBuffer[P] = Buffer[P];
	}

	/*** Now do Mono - Stereo Conversion ***/
	ms = count;
	do
	{
		c = 0xffff & *s++;
		*d++ = (c | (c<<16));
	} while(--ms);

	buffSize[whichab] += ( count << 2 );
	/*** This is the kicker for the entire audio loop ***/
	if ( isPlaying == 0 )
	{
		if ( buffSize[whichab] > AUDIOBUFFER )
		{
			isPlaying = 1;
			AudioSwitchBuffers();
		}
	}

	isWriting = 0;
}