gsplus/src/sdl2snd_driver.c

/*
  GSPLUS - Advanced Apple IIGS Emulator Environment
  Based on the KEGS emulator written by Kent Dickey
  See COPYRIGHT.txt for Copyright information
	See LICENSE.txt for license (GPL v2)
*/

#include "SDL.h"
#include "defc.h"
#include "glog.h"
#include "sound.h"
#include <assert.h>
extern word32	*g_sound_shm_addr;
extern int	g_sound_shm_pos;
extern int	g_audio_enable;
extern int g_preferred_rate;

static byte *playbuf = 0;
static int g_playbuf_buffered = 0;
static SDL_AudioSpec spec;
static int snd_buf;
static int snd_write;           /* write position into playbuf */
static /* volatile */ int snd_read = 0;
static int g_sound_paused;
static int g_zeroes_buffered;
static int g_zeroes_seen;
// newer SDL allows you to specify devices.  for now, we use what it gives us,
// but this can be made configurable in the future
SDL_AudioDeviceID dev = 0;


void sdlsnd_init(word32 *shmaddr)
{
  if (SDL_Init(SDL_INIT_AUDIO) < 0) {
		glog("Could not initialize SDL2 audio");
		g_audio_enable = 0;
	} else {
		glog("SDL2 audio initialized");
	}

  child_sound_loop(-1, -1, shmaddr);
  return;
}


void
sound_write_sdl(int real_samps, int size)
{

#ifdef HAVE_SDL
    int shm_read;

    if (real_samps) {
        shm_read = (g_sound_shm_pos - size + SOUND_SHM_SAMP_SIZE)%SOUND_SHM_SAMP_SIZE;
        SDL_LockAudioDevice(dev);
        while(size > 0) {
            if(g_playbuf_buffered >= snd_buf) {
                printf("sound_write_sdl failed @%d, %d buffered, %d samples skipped\n",snd_write,g_playbuf_buffered, size);
                shm_read += size;
                shm_read %= SOUND_SHM_SAMP_SIZE;
                size = 0;
            } else {
                ((word32*)playbuf)[snd_write/SAMPLE_CHAN_SIZE] = g_sound_shm_addr[shm_read];
                shm_read++;
                if (shm_read >= SOUND_SHM_SAMP_SIZE)
                    shm_read = 0;
                snd_write += SAMPLE_CHAN_SIZE;
                if (snd_write >= snd_buf)
                    snd_write = 0;
                size--;
                g_playbuf_buffered += SAMPLE_CHAN_SIZE;
            }
        }

        assert((snd_buf+snd_write - snd_read)%snd_buf == g_playbuf_buffered%snd_buf);
        assert(g_sound_shm_pos == shm_read);
        SDL_UnlockAudioDevice(dev);
    }
    if(g_sound_paused && (g_playbuf_buffered > 0)) {
        glogf("Unpausing sound, %d buffered",g_playbuf_buffered);
        g_sound_paused = 0;
        SDL_PauseAudioDevice(dev, 0);
    }
    if(!g_sound_paused && (g_playbuf_buffered <= 0)) {
        glog("Pausing sound");
        g_sound_paused = 1;
        SDL_PauseAudioDevice(dev, 1);
    }
#endif
}

#ifdef HAVE_SDL
/* Callback for sound */
static void _snd_callback(void* userdata, Uint8 *stream, int len)
{
    int i;
    /* Slurp off the play buffer */
    assert((snd_buf+snd_write - snd_read)%snd_buf == g_playbuf_buffered%snd_buf);
    /*printf("slurp %d, %d buffered\n",len, g_playbuf_buffered);*/
    for(i = 0; i < len; ++i) {
        if(g_playbuf_buffered <= 0) {
            stream[i] = 0;
        } else {
            stream[i] = playbuf[snd_read++];
            if(snd_read == snd_buf)
                snd_read = 0;
            g_playbuf_buffered--;
        }
    }
#if 0
    if (g_playbuf_buffered <= 0) {
        printf("snd_callback: buffer empty, Pausing sound\n");
        g_sound_paused = 1;
        SDL_PauseAudio(1);
    }
#endif
    //printf("end slurp %d, %d buffered\n",len, g_playbuf_buffered);
}
#endif




long
sound_init_device_sdl()
{
#ifdef HAVE_SDL
    long rate;
    SDL_AudioSpec wanted;

    if (SDL_Init(SDL_INIT_AUDIO) < 0) {
      glogf("SDL2 Couldn't init SDL_INIT_AUDIO: %s!", SDL_GetError());
      return 0;
    }

    /* Set the desired format */
    wanted.freq = g_preferred_rate;
    wanted.format = AUDIO_S16SYS;
    wanted.channels = NUM_CHANNELS;
    wanted.samples = 512;
    wanted.callback = _snd_callback;
    wanted.userdata = NULL;

    /* Open audio, and get the real spec */
    dev = SDL_OpenAudioDevice(NULL, 0, &wanted, &spec, 0);
    if (dev == 0) {
      glogf("SDL2 Couldn't open audio: %s!", SDL_GetError());
      SDL_QuitSubSystem(SDL_INIT_AUDIO);
      return 0;

    } else {
      glogf("SDL2 opened audio device: %d", dev);
    }

    /* Check everything */
    if(spec.channels != wanted.channels) {
        glogf("SDL2 Warning, couldn't get stereo audio format!");
        //goto snd_error;
    }
    if(spec.format != wanted.format) {
        glog("SDL2 Warning, couldn't get a supported audio format!");
        glogf("SDL2 wanted %X, got %X",wanted.format,spec.format);
        //goto snd_error;
    }
    if(spec.freq != wanted.freq) {
        glogf("SDL2 wanted rate = %d, got rate = %d", wanted.freq, spec.freq);
    }
    /* Set things as they really are */
    rate = spec.freq;

    snd_buf = SOUND_SHM_SAMP_SIZE*SAMPLE_CHAN_SIZE;
    playbuf = (byte*) malloc(snd_buf);
    if (!playbuf)
        goto snd_error;
    g_playbuf_buffered = 0;

    glogf("SDL2 sound shared memory size=%d", SOUND_SHM_SAMP_SIZE * SAMPLE_CHAN_SIZE);

    g_sound_shm_addr = malloc(SOUND_SHM_SAMP_SIZE * SAMPLE_CHAN_SIZE);
    memset(g_sound_shm_addr,0,SOUND_SHM_SAMP_SIZE * SAMPLE_CHAN_SIZE);

    /* It's all good! */
    g_zeroes_buffered = 0;
    g_zeroes_seen = 0;
    /* Let's start playing sound */
    g_sound_paused = 0;
    SDL_PauseAudioDevice(dev, 0);

		set_audio_rate(rate);
		return rate;

  snd_error:
    /* Oops! Something bad happened, cleanup. */
    SDL_CloseAudioDevice(dev);
    SDL_QuitSubSystem(SDL_INIT_AUDIO);
    if(playbuf)
        free((void*)playbuf);
    playbuf = 0;
    snd_buf = 0;
    return 0;
#else
    return 0;
#endif
}

void
sound_shutdown_sdl()
{
#ifdef HAVE_SDL
    SDL_CloseAudioDevice(dev);
    if(playbuf)
        free((void*)playbuf);
    playbuf = 0;
#endif
}