mirror of
https://github.com/ekeeke/Genesis-Plus-GX.git
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94 lines
2.5 KiB
C
94 lines
2.5 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[2][3840] ATTRIBUTE_ALIGN(32);
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u8 mixbuffer = 0;
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static int IsPlaying = 0;
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static int dma_len = 3200;
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/*** AudioDmaCallback
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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, we synchronize emulation with audio DMA
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This ensure we only update audio framebuffer when DMA is finished
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***/
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static void AudioDmaCallback()
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{
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frameticker++;
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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 (AudioDmaCallback);
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mixbuffer = 0;
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memset(soundbuffer, 0, 2 * 3840);
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}
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void ogc_audio__update(void)
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{
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/* buffer size */
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uint32 dma_len = vdp_pal ? 3840 : 3200;
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/* update DMA settings (this will only be taken in account when current DMA finishes) */
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AUDIO_InitDMA((u32) soundbuffer[mixbuffer], dma_len);
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/* flush data from CPU cache */
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DCFlushRange(soundbuffer[mixbuffer], dma_len);
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/* switch buffer */
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mixbuffer ^= 1;
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}
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void ogc_audio__stop(void)
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{
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/* stop audio DMA */
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AUDIO_StopDMA ();
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IsPlaying = 0;
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/* reset audio buffers */
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mixbuffer = 0;
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memset(soundbuffer, 0, 2 * 3840);
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}
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void ogc_audio__start(void)
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{
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if (!IsPlaying)
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{
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/* buffer size */
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dma_len = vdp_pal ? 3840 : 3200;
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/* set first DMA parameters */
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AUDIO_InitDMA((u32) soundbuffer[1], dma_len);
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/* start audio DMA */
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AUDIO_StartDMA();
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IsPlaying = 1;
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}
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}
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