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https://github.com/dborth/vbagx.git
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142 lines
3.3 KiB
C++
142 lines
3.3 KiB
C++
/****************************************************************************
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* Visual Boy Advance GX
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*
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* Tantric September 2008
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*
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* audio.cpp
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*
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* Head and tail audio mixer
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***************************************************************************/
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#include <gccore.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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/** Locals **/
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static int head = 0;
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static int tail = 0;
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#define MIXBUFFSIZE 0x10000
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static u8 mixerdata[MIXBUFFSIZE];
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#define MIXERMASK ((MIXBUFFSIZE >> 2) - 1)
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#define SWAP(x) ((x>>16)|(x<<16)) // for reversing stereo channels
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static u8 soundbuffer[2][3840] ATTRIBUTE_ALIGN(32);
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extern int ConfigRequested;
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static int whichab = 0;
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int IsPlaying = 0;
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/****************************************************************************
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* MIXER_GetSamples
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***************************************************************************/
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static int MIXER_GetSamples( u8 *dstbuffer, int maxlen )
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{
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u32 *src = (u32 *)mixerdata;
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u32 *dst = (u32 *)dstbuffer;
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u32 intlen = maxlen >> 2;
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memset(dstbuffer, 0, maxlen);
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while( ( head != tail ) && intlen )
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{
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*dst++ = src[tail++];
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tail &= MIXERMASK;
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intlen--;
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}
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return 3200;
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}
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/****************************************************************************
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* MIXER_GetSamples
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***************************************************************************/
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static void AudioPlayer()
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{
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if ( !ConfigRequested )
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{
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int len = MIXER_GetSamples(soundbuffer[whichab], 3200);
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DCFlushRange(soundbuffer[whichab],len);
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AUDIO_InitDMA((u32)soundbuffer[whichab],len);
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AUDIO_StartDMA();
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whichab ^= 1;
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IsPlaying = 1;
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}
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else
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IsPlaying = 0;
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}
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/****************************************************************************
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* MIXER_AddSamples
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*
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* Upsample from 11025 to 48000
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* 11025 == 15052
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* 22050 == 30106
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* 44100 == 60211
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*
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* Audio officianados should look away now !
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****************************************************************************/
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void MIXER_AddSamples( u8 *sampledata, int len )
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{
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u32 *src = (u32 *)sampledata;
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u32 *dst = (u32 *)mixerdata;
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u32 intlen = (3200 >> 2);
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u32 fixofs = 0;
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u32 fixinc;
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if ( !len )
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fixinc = 30106;
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else
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fixinc = 60211;
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do
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{
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// Do simple linear interpolate, and swap channels from L-R to R-L
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dst[head++] = SWAP(src[fixofs >> 16]);
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head &= MIXERMASK;
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fixofs += fixinc;
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}
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while( --intlen );
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// Restart Sound Processing if stopped
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if (IsPlaying == 0)
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{
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ConfigRequested = 0;
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AudioPlayer();
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}
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}
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/****************************************************************************
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* MIXER_GetSamples
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***************************************************************************/
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void InitialiseSound()
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{
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AUDIO_Init(NULL); // Start audio subsystem
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AUDIO_SetDSPSampleRate(AI_SAMPLERATE_48KHZ);
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AUDIO_RegisterDMACallback(AudioPlayer);
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memset(soundbuffer, 0, 3840*2);
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memset(mixerdata, 0, MIXBUFFSIZE);
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}
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/****************************************************************************
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* MIXER_GetSamples
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***************************************************************************/
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void ResetAudio()
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{
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memset(soundbuffer, 0, 3840*2);
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memset(mixerdata, 0, MIXBUFFSIZE);
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}
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/****************************************************************************
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* MIXER_GetSamples
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***************************************************************************/
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void StopAudio()
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{
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AUDIO_StopDMA();
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IsPlaying = 0;
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}
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