kolibrios/contrib/other/sdlquake-1.0.9/snd_sdl.c

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#include <stdio.h>
#include "SDL_audio.h"
#include "SDL_byteorder.h"
#include "quakedef.h"
static dma_t the_shm;
static int snd_inited;
extern int desired_speed;
extern int desired_bits;
static void paint_audio(void *unused, Uint8 *stream, int len)
{
if ( shm ) {
shm->buffer = stream;
shm->samplepos += len/(shm->samplebits/8)/2;
// Check for samplepos overflow?
S_PaintChannels (shm->samplepos);
}
}
qboolean SNDDMA_Init(void)
{
SDL_AudioSpec desired, obtained;
snd_inited = 0;
/* Set up the desired format */
desired.freq = desired_speed;
switch (desired_bits) {
case 8:
desired.format = AUDIO_U8;
break;
case 16:
if ( SDL_BYTEORDER == SDL_BIG_ENDIAN )
desired.format = AUDIO_S16MSB;
else
desired.format = AUDIO_S16LSB;
break;
default:
Con_Printf("Unknown number of audio bits: %d\n",
desired_bits);
return 0;
}
desired.channels = 2;
desired.samples = 512;
desired.callback = paint_audio;
/* Open the audio device */
if ( SDL_OpenAudio(&desired, &obtained) < 0 ) {
Con_Printf("Couldn't open SDL audio: %s\n", SDL_GetError());
return 0;
}
/* Make sure we can support the audio format */
switch (obtained.format) {
case AUDIO_U8:
/* Supported */
break;
case AUDIO_S16LSB:
case AUDIO_S16MSB:
if ( ((obtained.format == AUDIO_S16LSB) &&
(SDL_BYTEORDER == SDL_LIL_ENDIAN)) ||
((obtained.format == AUDIO_S16MSB) &&
(SDL_BYTEORDER == SDL_BIG_ENDIAN)) ) {
/* Supported */
break;
}
/* Unsupported, fall through */;
default:
/* Not supported -- force SDL to do our bidding */
SDL_CloseAudio();
if ( SDL_OpenAudio(&desired, NULL) < 0 ) {
Con_Printf("Couldn't open SDL audio: %s\n",
SDL_GetError());
return 0;
}
memcpy(&obtained, &desired, sizeof(desired));
break;
}
SDL_PauseAudio(0);
/* Fill the audio DMA information block */
shm = &the_shm;
shm->splitbuffer = 0;
shm->samplebits = (obtained.format & 0xFF);
shm->speed = obtained.freq;
shm->channels = obtained.channels;
shm->samples = obtained.samples*shm->channels;
shm->samplepos = 0;
shm->submission_chunk = 1;
shm->buffer = NULL;
snd_inited = 1;
return 1;
}
int SNDDMA_GetDMAPos(void)
{
return shm->samplepos;
}
void SNDDMA_Shutdown(void)
{
if (snd_inited)
{
SDL_CloseAudio();
snd_inited = 0;
}
}