SDL_mintaudio.c
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SDL - Simple DirectMedia Layer
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Copyright (C) 1997-2004 Sam Lantinga
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This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
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This library 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
Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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Sam Lantinga
slouken@libsdl.org
*/
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/*
Audio interrupt variables and callback function
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Patrice Mandin
*/
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#include <string.h>
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#include "SDL_types.h"
#include "SDL_audio.h"
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#include "SDL_mintaudio.h"
#include "SDL_mintaudio_stfa.h"
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/* The audio device */
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SDL_AudioDevice *SDL_MintAudio_device;
Uint8 *SDL_MintAudio_audiobuf[2]; /* Pointers to buffers */
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unsigned long SDL_MintAudio_audiosize; /* Length of audio buffer=spec->size */
unsigned short SDL_MintAudio_numbuf; /* Buffer to play */
unsigned short SDL_MintAudio_mutex;
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unsigned long SDL_MintAudio_clocktics;
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cookie_stfa_t *SDL_MintAudio_stfa;
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/* The callback function, called by each driver whenever needed */
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void SDL_MintAudio_Callback(void)
{
Uint8 *buffer;
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SDL_AudioDevice *audio = SDL_MintAudio_device;
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buffer = SDL_MintAudio_audiobuf[SDL_MintAudio_numbuf];
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memset(buffer, audio->spec.silence, audio->spec.size);
if (audio->paused)
return;
if (audio->convert.needed) {
int silence;
if ( audio->convert.src_format == AUDIO_U8 ) {
silence = 0x80;
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} else {
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silence = 0;
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memset(audio->convert.buf, silence, audio->convert.len);
audio->spec.callback(audio->spec.userdata,
(Uint8 *)audio->convert.buf,audio->convert.len);
SDL_ConvertAudio(&audio->convert);
memcpy(buffer, audio->convert.buf, audio->convert.len_cvt);
} else {
audio->spec.callback(audio->spec.userdata, buffer, audio->spec.size);
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/* Add a new frequency/clock/predivisor to the current list */
void SDL_MintAudio_AddFrequency(_THIS, Uint32 frequency, Uint32 clock, Uint32 prediv)
{
int i, p;
if (MINTAUDIO_freqcount==MINTAUDIO_maxfreqs) {
return;
}
/* Search where to insert the frequency (highest first) */
for (p=0; p<MINTAUDIO_freqcount; p++) {
if (frequency > MINTAUDIO_frequencies[p].frequency) {
break;
}
}
/* Put all following ones farer */
if (MINTAUDIO_freqcount>0) {
for (i=MINTAUDIO_freqcount; i>p; i--) {
MINTAUDIO_frequencies[i].frequency = MINTAUDIO_frequencies[i-1].frequency;
MINTAUDIO_frequencies[i].masterclock = MINTAUDIO_frequencies[i-1].masterclock;
MINTAUDIO_frequencies[i].predivisor = MINTAUDIO_frequencies[i-1].predivisor;
}
}
/* And insert new one */
MINTAUDIO_frequencies[p].frequency = frequency;
MINTAUDIO_frequencies[p].masterclock = clock;
MINTAUDIO_frequencies[p].predivisor = prediv;
MINTAUDIO_freqcount++;
}
/* Search for the nearest frequency */
int SDL_MintAudio_SearchFrequency(_THIS, int desired_freq)
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{
int i;
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/* Only 1 freq ? */
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if (MINTAUDIO_freqcount==1) {
return 0;
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/* Check the array */
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for (i=0; i<MINTAUDIO_freqcount; i++) {
if (desired_freq >= ((MINTAUDIO_frequencies[i].frequency+
MINTAUDIO_frequencies[i+1].frequency)>>1)) {
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return i;
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}
}
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/* Not in the array, give the latest */
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return MINTAUDIO_freqcount-1;