nkeynes@989: /**
nkeynes@1021:  * $Id$
nkeynes@989:  * 
nkeynes@989:  * The SDL sound driver
nkeynes@989:  *
nkeynes@989:  * Copyright (c) 2009 wahrhaft
nkeynes@989:  *
nkeynes@989:  * This program is free software; you can redistribute it and/or modify
nkeynes@989:  * it under the terms of the GNU General Public License as published by
nkeynes@989:  * the Free Software Foundation; either version 2 of the License, or
nkeynes@989:  * (at your option) any later version.
nkeynes@989:  *
nkeynes@989:  * This program is distributed in the hope that it will be useful,
nkeynes@989:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
nkeynes@989:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
nkeynes@989:  * GNU General Public License for more details.
nkeynes@989:  */
nkeynes@989: #include <stdio.h>
nkeynes@989: #include <unistd.h>
nkeynes@989: #include <SDL/SDL.h>
nkeynes@989: #include <SDL/SDL_audio.h>
nkeynes@989: #include "aica/audio.h"
nkeynes@989: #include "lxdream.h"
nkeynes@989: 
nkeynes@989: #define SDL_SAMPLES 512        //tweaking this value may help with audio dropouts
nkeynes@989: #define BYTES_PER_SAMPLE 4     //should be changed if samples are not S16 stereo
nkeynes@989: 
nkeynes@989: #define BUFFER_MIN_SIZE SDL_SAMPLES * BYTES_PER_SAMPLE * 4
nkeynes@989: #define BUFFER_MAX_SIZE SDL_SAMPLES * BYTES_PER_SAMPLE * 16
nkeynes@989: 
nkeynes@989: char *audio_buffer;
nkeynes@989: int buffer_pos;
nkeynes@989: 
nkeynes@989: void mix_audio(void *userdata, Uint8 *stream, int len);
nkeynes@994: void audio_sdl_start();
nkeynes@989: 
nkeynes@989: gboolean audio_sdl_init( )
nkeynes@989: {
nkeynes@989:     int rate = DEFAULT_SAMPLE_RATE;
nkeynes@989:     int format = DEFAULT_SAMPLE_FORMAT;
nkeynes@989:     
nkeynes@989:     SDL_AudioSpec fmt;
nkeynes@989:     fmt.freq = rate;
nkeynes@989:     if (format & AUDIO_FMT_16BIT) 
nkeynes@989:         fmt.format = AUDIO_S16;
nkeynes@989:     else
nkeynes@989:         fmt.format = AUDIO_U8;
nkeynes@989:     if (format & AUDIO_FMT_STEREO)
nkeynes@989:         fmt.channels = 2;
nkeynes@989:     else
nkeynes@989:         fmt.channels = 1;
nkeynes@989:     
nkeynes@989:     fmt.samples = SDL_SAMPLES;
nkeynes@989:     fmt.callback = mix_audio;
nkeynes@989:     fmt.userdata = NULL;
nkeynes@989:     
nkeynes@989:     if (SDL_OpenAudio(&fmt, NULL) < 0)
nkeynes@989:     {
nkeynes@989:         ERROR("Unable to open audio output (SDL)");
nkeynes@989:         return FALSE;
nkeynes@989:     }
nkeynes@989:     buffer_pos = 0;
nkeynes@989:     audio_buffer = (char*)malloc(BUFFER_MAX_SIZE * sizeof(char));
nkeynes@989:     if (audio_buffer == NULL)
nkeynes@989:     {
nkeynes@989:         ERROR("Could not allocate audio buffer (SDL)");
nkeynes@989:         return FALSE;
nkeynes@989:     }
nkeynes@989:     
nkeynes@989:     //hmm, this doesn't seem to get called externally...
nkeynes@989:     audio_sdl_start();
nkeynes@989:     
nkeynes@989:     return TRUE;
nkeynes@989: }
nkeynes@989: 
nkeynes@989: gboolean audio_sdl_process_buffer( audio_buffer_t buffer )
nkeynes@989: {
nkeynes@989:     SDL_LockAudio();
nkeynes@989:     if (buffer_pos + buffer->length >= BUFFER_MAX_SIZE)
nkeynes@989:     {
nkeynes@989:         printf("Audio buffer full, dropping a chunk\n");
nkeynes@989:     }
nkeynes@989:     else
nkeynes@989:     {
nkeynes@989:         memcpy(audio_buffer, buffer->data, buffer->length);
nkeynes@989:         buffer_pos += buffer->length;
nkeynes@989:     }
nkeynes@989:     SDL_UnlockAudio();
nkeynes@989: 
nkeynes@989:     return TRUE;    
nkeynes@989: }
nkeynes@989: 
nkeynes@989: void mix_audio(void *userdata, Uint8 *stream, int len)
nkeynes@989: {
nkeynes@989:     if (len < buffer_pos)
nkeynes@989:     {
nkeynes@989:         memcpy(stream, audio_buffer, len);
nkeynes@989:     }
nkeynes@989:     if (buffer_pos > BUFFER_MIN_SIZE)
nkeynes@989:     {
nkeynes@989:         memcpy(audio_buffer, &audio_buffer[len], buffer_pos - len);
nkeynes@989:         buffer_pos -= len;
nkeynes@989:     }
nkeynes@989:     else
nkeynes@989:     {
nkeynes@989:         //printf("Audio buffer low, repeating a chunk\n");
nkeynes@989:     }
nkeynes@989: }
nkeynes@989: 
nkeynes@989: gboolean audio_sdl_shutdown()
nkeynes@989: {
nkeynes@989:     SDL_CloseAudio();
nkeynes@989:     free(audio_buffer);
nkeynes@989:     return TRUE;
nkeynes@989: }
nkeynes@989: 
nkeynes@989: void audio_sdl_start()
nkeynes@989: {
nkeynes@989:     SDL_PauseAudio(0);
nkeynes@989: }
nkeynes@989: 
nkeynes@989: void audio_sdl_stop()
nkeynes@989: {
nkeynes@989:     SDL_PauseAudio(1);
nkeynes@989: }
nkeynes@989: 
nkeynes@989: struct audio_driver audio_sdl_driver = { 
nkeynes@989:     "sdl",
nkeynes@989:     N_("SDL sound driver"),
nkeynes@989:     DEFAULT_SAMPLE_RATE,
nkeynes@989:     DEFAULT_SAMPLE_FORMAT,
nkeynes@989:     audio_sdl_init,
nkeynes@989:     audio_sdl_start,
nkeynes@989:     audio_sdl_process_buffer,
nkeynes@989:     audio_sdl_stop,
nkeynes@989:     audio_sdl_shutdown
nkeynes@989: };
nkeynes@989: