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/* SDL Driver for P.E.Op.S Sound Plugin
* Copyright (c) 2010, Wei Mingzhi <whistler_wmz@users.sf.net>.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111-1307 USA
*/
#include <stdlib.h>
#include <SDL.h>
#include "out.h"
#define BUFFER_SIZE 22050
short *pSndBuffer = NULL;
int iBufSize = 0;
volatile int iReadPos = 0, iWritePos = 0;
static void SOUND_FillAudio(void *unused, Uint8 *stream, int len) {
short *p = (short *)stream;
len /= sizeof(short);
while (iReadPos != iWritePos && len > 0) {
*p++ = pSndBuffer[iReadPos++];
if (iReadPos >= iBufSize) iReadPos = 0;
--len;
}
// Fill remaining space with zero
while (len > 0) {
*p++ = 0;
--len;
}
}
static void InitSDL() {
if (SDL_WasInit(SDL_INIT_EVERYTHING)) {
SDL_InitSubSystem(SDL_INIT_AUDIO);
} else {
SDL_Init(SDL_INIT_AUDIO | SDL_INIT_NOPARACHUTE);
}
}
static void DestroySDL() {
if (SDL_WasInit(SDL_INIT_EVERYTHING & ~SDL_INIT_AUDIO)) {
SDL_QuitSubSystem(SDL_INIT_AUDIO);
} else {
SDL_Quit();
}
}
static int sdl_init(void) {
SDL_AudioSpec spec;
if (pSndBuffer != NULL) return -1;
InitSDL();
spec.freq = 44100;
spec.format = AUDIO_S16SYS;
spec.channels = 2;
spec.samples = 512;
spec.callback = SOUND_FillAudio;
if (SDL_OpenAudio(&spec, NULL) < 0) {
DestroySDL();
return -1;
}
iBufSize = BUFFER_SIZE;
pSndBuffer = (short *)malloc(iBufSize * sizeof(short));
if (pSndBuffer == NULL) {
SDL_CloseAudio();
return -1;
}
iReadPos = 0;
iWritePos = 0;
SDL_PauseAudio(0);
return 0;
}
static void sdl_finish(void) {
if (pSndBuffer == NULL) return;
SDL_CloseAudio();
DestroySDL();
free(pSndBuffer);
pSndBuffer = NULL;
}
static int sdl_busy(void) {
int size;
if (pSndBuffer == NULL) return 1;
size = iReadPos - iWritePos;
if (size <= 0) size += iBufSize;
if (size < iBufSize / 2) return 1;
return 0;
}
static void sdl_feed(void *pSound, int lBytes) {
short *p = (short *)pSound;
if (pSndBuffer == NULL) return;
while (lBytes > 0) {
if (((iWritePos + 1) % iBufSize) == iReadPos) break;
pSndBuffer[iWritePos] = *p++;
++iWritePos;
if (iWritePos >= iBufSize) iWritePos = 0;
lBytes -= sizeof(short);
}
}
void out_register_sdl(struct out_driver *drv)
{
drv->name = "sdl";
drv->init = sdl_init;
drv->finish = sdl_finish;
drv->busy = sdl_busy;
drv->feed = sdl_feed;
}
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