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https://github.com/ekeeke/Genesis-Plus-GX.git
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88 lines
2.4 KiB
C
88 lines
2.4 KiB
C
/****************************************************************************
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* ogc_audio.c
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*
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* Genesis Plus GX audio support
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*
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* code by Softdev (2006), Eke-Eke (2007,2008)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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***************************************************************************/
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#include "shared.h"
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/* global datas */
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unsigned char soundbuffer[16][3840] ATTRIBUTE_ALIGN(32);
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int mixbuffer = 0;
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static int playbuffer = 0;
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static int IsPlaying = 0;
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/*** AudioSwitchBuffers
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Genesis Plus only provides sound data on completion of each frame.
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To try to make the audio less choppy, this function is called from both the
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DMA completion and update_audio.
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Testing for data in the buffer ensures that there are no clashes.
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***/
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static void AudioSwitchBuffers()
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{
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if (ConfigRequested)
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{
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IsPlaying = 0;
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return;
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}
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u32 dma_len = (vdp_pal) ? 3840 : 3200;
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/* restart audio DMA with current soundbuffer */
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AUDIO_InitDMA((u32) soundbuffer[playbuffer], dma_len);
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DCFlushRange(soundbuffer[playbuffer], dma_len);
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AUDIO_StartDMA();
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/* increment soundbuffers index */
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playbuffer++;
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playbuffer &= 0xf;
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if (playbuffer == mixbuffer)
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{
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playbuffer--;
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if ( playbuffer < 0 ) playbuffer = 15;
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}
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IsPlaying = 1;
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}
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void ogc_audio__init(void)
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{
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AUDIO_Init (NULL);
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AUDIO_SetDSPSampleRate (AI_SAMPLERATE_48KHZ);
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AUDIO_RegisterDMACallback (AudioSwitchBuffers);
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}
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void ogc_audio__reset(void)
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{
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AUDIO_StopDMA ();
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IsPlaying = 0;
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mixbuffer = 0;
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playbuffer = 0;
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memset(soundbuffer, 0, 16 * 3840);
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}
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void ogc_audio__update(void)
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{
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/* restart Audio DMA if needed */
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if (!IsPlaying) AudioSwitchBuffers();
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}
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