audio/sdlaudio.c

/*
 * QEMU SDL audio driver
 *
 * Copyright (c) 2004-2005 Vassili Karpov (malc)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#include "qemu/osdep.h"
#include <SDL.h>
#include <SDL_thread.h>
#include "qemu-common.h"
#include "audio.h"

#ifndef _WIN32
#ifdef __sun__
#define _POSIX_PTHREAD_SEMANTICS 1
#elif defined(__OpenBSD__) || defined(__FreeBSD__) || defined(__DragonFly__)
#include <pthread.h>
#endif
#endif

#define AUDIO_CAP "sdl"
#include "audio_int.h"

#define USE_SEMAPHORE (SDL_MAJOR_VERSION < 2)

typedef struct SDLVoiceOut {
    HWVoiceOut hw;
    int live;
#if USE_SEMAPHORE
    int rpos;
#endif
    int decr;
} SDLVoiceOut;

static struct {
    int nb_samples;
} conf = {
    .nb_samples = 1024
};

static struct SDLAudioState {
    int exit;
#if USE_SEMAPHORE
    SDL_mutex *mutex;
    SDL_sem *sem;
#endif
    int initialized;
    bool driver_created;
} glob_sdl;
typedef struct SDLAudioState SDLAudioState;

static void GCC_FMT_ATTR (1, 2) sdl_logerr (const char *fmt, ...)
{
    va_list ap;

    va_start (ap, fmt);
    AUD_vlog (AUDIO_CAP, fmt, ap);
    va_end (ap);

    AUD_log (AUDIO_CAP, "Reason: %s\n", SDL_GetError ());
}

static int sdl_lock (SDLAudioState *s, const char *forfn)
{
#if USE_SEMAPHORE
    if (SDL_LockMutex (s->mutex)) {
        sdl_logerr ("SDL_LockMutex for %s failed\n", forfn);
        return -1;
    }
#else
    SDL_LockAudio();
#endif

    return 0;
}

static int sdl_unlock (SDLAudioState *s, const char *forfn)
{
#if USE_SEMAPHORE
    if (SDL_UnlockMutex (s->mutex)) {
        sdl_logerr ("SDL_UnlockMutex for %s failed\n", forfn);
        return -1;
    }
#else
    SDL_UnlockAudio();
#endif

    return 0;
}

static int sdl_post (SDLAudioState *s, const char *forfn)
{
#if USE_SEMAPHORE
    if (SDL_SemPost (s->sem)) {
        sdl_logerr ("SDL_SemPost for %s failed\n", forfn);
        return -1;
    }
#endif

    return 0;
}

#if USE_SEMAPHORE
static int sdl_wait (SDLAudioState *s, const char *forfn)
{
    if (SDL_SemWait (s->sem)) {
        sdl_logerr ("SDL_SemWait for %s failed\n", forfn);
        return -1;
    }
    return 0;
}
#endif

static int sdl_unlock_and_post (SDLAudioState *s, const char *forfn)
{
    if (sdl_unlock (s, forfn)) {
        return -1;
    }

    return sdl_post (s, forfn);
}

static int aud_to_sdlfmt (audfmt_e fmt)
{
    switch (fmt) {
    case AUD_FMT_S8:
        return AUDIO_S8;

    case AUD_FMT_U8:
        return AUDIO_U8;

    case AUD_FMT_S16:
        return AUDIO_S16LSB;

    case AUD_FMT_U16:
        return AUDIO_U16LSB;

    default:
        dolog ("Internal logic error: Bad audio format %d\n", fmt);
#ifdef DEBUG_AUDIO
        abort ();
#endif
        return AUDIO_U8;
    }
}

static int sdl_to_audfmt(int sdlfmt, audfmt_e *fmt, int *endianness)
{
    switch (sdlfmt) {
    case AUDIO_S8:
        *endianness = 0;
        *fmt = AUD_FMT_S8;
        break;

    case AUDIO_U8:
        *endianness = 0;
        *fmt = AUD_FMT_U8;
        break;

    case AUDIO_S16LSB:
        *endianness = 0;
        *fmt = AUD_FMT_S16;
        break;

    case AUDIO_U16LSB:
        *endianness = 0;
        *fmt = AUD_FMT_U16;
        break;

    case AUDIO_S16MSB:
        *endianness = 1;
        *fmt = AUD_FMT_S16;
        break;

    case AUDIO_U16MSB:
        *endianness = 1;
        *fmt = AUD_FMT_U16;
        break;

    default:
        dolog ("Unrecognized SDL audio format %d\n", sdlfmt);
        return -1;
    }

    return 0;
}

static int sdl_open (SDL_AudioSpec *req, SDL_AudioSpec *obt)
{
    int status;
#ifndef _WIN32
    int err;
    sigset_t new, old;

    /* Make sure potential threads created by SDL don't hog signals.  */
    err = sigfillset (&new);
    if (err) {
        dolog ("sdl_open: sigfillset failed: %s\n", strerror (errno));
        return -1;
    }
    err = pthread_sigmask (SIG_BLOCK, &new, &old);
    if (err) {
        dolog ("sdl_open: pthread_sigmask failed: %s\n", strerror (err));
        return -1;
    }
#endif

    status = SDL_OpenAudio (req, obt);
    if (status) {
        sdl_logerr ("SDL_OpenAudio failed\n");
    }

#ifndef _WIN32
    err = pthread_sigmask (SIG_SETMASK, &old, NULL);
    if (err) {
        dolog ("sdl_open: pthread_sigmask (restore) failed: %s\n",
               strerror (errno));
        /* We have failed to restore original signal mask, all bets are off,
           so exit the process */
        exit (EXIT_FAILURE);
    }
#endif
    return status;
}

static void sdl_close (SDLAudioState *s)
{
    if (s->initialized) {
        sdl_lock (s, "sdl_close");
        s->exit = 1;
        sdl_unlock_and_post (s, "sdl_close");
        SDL_PauseAudio (1);
        SDL_CloseAudio ();
        s->initialized = 0;
    }
}

static void sdl_callback (void *opaque, Uint8 *buf, int len)
{
    SDLVoiceOut *sdl = opaque;
    SDLAudioState *s = &glob_sdl;
    HWVoiceOut *hw = &sdl->hw;
    int samples = len >> hw->info.shift;

    if (s->exit) {
        return;
    }

    while (samples) {
        int to_mix, decr;

        /* dolog ("in callback samples=%d\n", samples); */
#if USE_SEMAPHORE
        sdl_wait (s, "sdl_callback");
        if (s->exit) {
            return;
        }

        if (sdl_lock (s, "sdl_callback")) {
            return;
        }

        if (audio_bug(__func__, sdl->live < 0 || sdl->live > hw->samples)) {
            dolog ("sdl->live=%d hw->samples=%d\n",
                   sdl->live, hw->samples);
            return;
        }

        if (!sdl->live) {
            goto again;
        }
#else
        if (s->exit || !sdl->live) {
            break;
        }
#endif

        /* dolog ("in callback live=%d\n", live); */
        to_mix = audio_MIN (samples, sdl->live);
        decr = to_mix;
        while (to_mix) {
            int chunk = audio_MIN (to_mix, hw->samples - hw->rpos);
            struct st_sample *src = hw->mix_buf + hw->rpos;

            /* dolog ("in callback to_mix %d, chunk %d\n", to_mix, chunk); */
            hw->clip (buf, src, chunk);
#if USE_SEMAPHORE
            sdl->rpos = (sdl->rpos + chunk) % hw->samples;
#else
            hw->rpos = (hw->rpos + chunk) % hw->samples;
#endif
            to_mix -= chunk;
            buf += chunk << hw->info.shift;
        }
        samples -= decr;
        sdl->live -= decr;
        sdl->decr += decr;

#if USE_SEMAPHORE
    again:
        if (sdl_unlock (s, "sdl_callback")) {
            return;
        }
#endif
    }
    /* dolog ("done len=%d\n", len); */

#if (SDL_MAJOR_VERSION >= 2)
    /* SDL2 does not clear the remaining buffer for us, so do it on our own */
    if (samples) {
        memset(buf, 0, samples << hw->info.shift);
    }
#endif
}

static int sdl_write_out (SWVoiceOut *sw, void *buf, int len)
{
    return audio_pcm_sw_write (sw, buf, len);
}

static int sdl_run_out (HWVoiceOut *hw, int live)
{
    int decr;
    SDLVoiceOut *sdl = (SDLVoiceOut *) hw;
    SDLAudioState *s = &glob_sdl;

    if (sdl_lock (s, "sdl_run_out")) {
        return 0;
    }

    if (sdl->decr > live) {
        ldebug ("sdl->decr %d live %d sdl->live %d\n",
                sdl->decr,
                live,
                sdl->live);
    }

    decr = audio_MIN (sdl->decr, live);
    sdl->decr -= decr;

#if USE_SEMAPHORE
    sdl->live = live - decr;
    hw->rpos = sdl->rpos;
#else
    sdl->live = live;
#endif

    if (sdl->live > 0) {
        sdl_unlock_and_post (s, "sdl_run_out");
    }
    else {
        sdl_unlock (s, "sdl_run_out");
    }
    return decr;
}

static void sdl_fini_out (HWVoiceOut *hw)
{
    (void) hw;

    sdl_close (&glob_sdl);
}

static int sdl_init_out(HWVoiceOut *hw, struct audsettings *as,
                        void *drv_opaque)
{
    SDLVoiceOut *sdl = (SDLVoiceOut *) hw;
    SDLAudioState *s = &glob_sdl;
    SDL_AudioSpec req, obt;
    int endianness;
    int err;
    audfmt_e effective_fmt;
    struct audsettings obt_as;

    req.freq = as->freq;
    req.format = aud_to_sdlfmt (as->fmt);
    req.channels = as->nchannels;
    req.samples = conf.nb_samples;
    req.callback = sdl_callback;
    req.userdata = sdl;

    if (sdl_open (&req, &obt)) {
        return -1;
    }

    err = sdl_to_audfmt(obt.format, &effective_fmt, &endianness);
    if (err) {
        sdl_close (s);
        return -1;
    }

    obt_as.freq = obt.freq;
    obt_as.nchannels = obt.channels;
    obt_as.fmt = effective_fmt;
    obt_as.endianness = endianness;

    audio_pcm_init_info (&hw->info, &obt_as);
    hw->samples = obt.samples;

    s->initialized = 1;
    s->exit = 0;
    SDL_PauseAudio (0);
    return 0;
}

static int sdl_ctl_out (HWVoiceOut *hw, int cmd, ...)
{
    (void) hw;

    switch (cmd) {
    case VOICE_ENABLE:
        SDL_PauseAudio (0);
        break;

    case VOICE_DISABLE:
        SDL_PauseAudio (1);
        break;
    }
    return 0;
}

static void *sdl_audio_init (void)
{
    SDLAudioState *s = &glob_sdl;
    if (s->driver_created) {
        sdl_logerr("Can't create multiple sdl backends\n");
        return NULL;
    }

    if (SDL_InitSubSystem (SDL_INIT_AUDIO)) {
        sdl_logerr ("SDL failed to initialize audio subsystem\n");
        return NULL;
    }

#if USE_SEMAPHORE
    s->mutex = SDL_CreateMutex ();
    if (!s->mutex) {
        sdl_logerr ("Failed to create SDL mutex\n");
        SDL_QuitSubSystem (SDL_INIT_AUDIO);
        return NULL;
    }

    s->sem = SDL_CreateSemaphore (0);
    if (!s->sem) {
        sdl_logerr ("Failed to create SDL semaphore\n");
        SDL_DestroyMutex (s->mutex);
        SDL_QuitSubSystem (SDL_INIT_AUDIO);
        return NULL;
    }
#endif

    s->driver_created = true;
    return s;
}

static void sdl_audio_fini (void *opaque)
{
    SDLAudioState *s = opaque;
    sdl_close (s);
#if USE_SEMAPHORE
    SDL_DestroySemaphore (s->sem);
    SDL_DestroyMutex (s->mutex);
#endif
    SDL_QuitSubSystem (SDL_INIT_AUDIO);
    s->driver_created = false;
}

static struct audio_option sdl_options[] = {
    {
        .name  = "SAMPLES",
        .tag   = AUD_OPT_INT,
        .valp  = &conf.nb_samples,
        .descr = "Size of SDL buffer in samples"
    },
    { /* End of list */ }
};

static struct audio_pcm_ops sdl_pcm_ops = {
    .init_out = sdl_init_out,
    .fini_out = sdl_fini_out,
    .run_out  = sdl_run_out,
    .write    = sdl_write_out,
    .ctl_out  = sdl_ctl_out,
};

static struct audio_driver sdl_audio_driver = {
    .name           = "sdl",
    .descr          = "SDL http://www.libsdl.org",
    .options        = sdl_options,
    .init           = sdl_audio_init,
    .fini           = sdl_audio_fini,
    .pcm_ops        = &sdl_pcm_ops,
    .can_be_default = 1,
    .max_voices_out = 1,
    .max_voices_in  = 0,
    .voice_size_out = sizeof (SDLVoiceOut),
    .voice_size_in  = 0
};

static void register_audio_sdl(void)
{
    audio_driver_register(&sdl_audio_driver);
}
type_init(register_audio_sdl);