src/audio/bsd/SDL_bsdaudio.c
author Ryan C. Gordon <icculus@icculus.org>
Wed, 04 Oct 2006 21:27:53 +0000
branchSDL-ryan-multiple-audio-device
changeset 3798 c8b3d3d13ed1
parent 1982 3b4ce57c6215
child 3816 9d070c1a45fa
permissions -rw-r--r--
Audio bootstraps can now specify that a driver is only to be used if explicitly requested (for things like the "disk" driver that is always available but you would never want to default to using). Trimmed out code that can be handled by stubs in the core. The "dummy" driver is pretty damned small now. :)

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2004 Sam Lantinga

    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.

    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.

    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

    Sam Lantinga
    slouken@libsdl.org
*/
#include "SDL_config.h"

/*
 * Driver for native OpenBSD/NetBSD audio(4).
 * vedge@vedge.com.ar.
 */

#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/audioio.h>

#include "SDL_timer.h"
#include "SDL_audio.h"
#include "../SDL_audiomem.h"
#include "../SDL_audio_c.h"
#include "../SDL_audiodev_c.h"
#include "SDL_bsdaudio.h"

/* The tag name used by NetBSD/OpenBSD audio */
#ifdef __NetBSD__
#define BSD_AUDIO_DRIVER_NAME         "netbsd"
#define BSD_AUDIO_DRIVER_DESC         "Native NetBSD audio"
#else
#define BSD_AUDIO_DRIVER_NAME         "openbsd"
#define BSD_AUDIO_DRIVER_DESC         "Native OpenBSD audio"
#endif

/* Open the audio device for playback, and don't block if busy */
/* #define USE_BLOCKING_WRITES */

/* Use timer for synchronization */
/* #define USE_TIMER_SYNC */

/* #define DEBUG_AUDIO */
/* #define DEBUG_AUDIO_STREAM */

#ifdef USE_BLOCKING_WRITES
#define OPEN_FLAGS	O_WRONLY
#else
#define OPEN_FLAGS	(O_WRONLY|O_NONBLOCK)
#endif

/* Audio driver functions */
static void OBSD_WaitAudio(_THIS);
static int OBSD_OpenAudio(_THIS, SDL_AudioSpec * spec);
static void OBSD_PlayAudio(_THIS);
static Uint8 *OBSD_GetAudioBuf(_THIS);
static void OBSD_CloseAudio(_THIS);

#ifdef DEBUG_AUDIO
static void OBSD_Status(_THIS);
#endif

/* Audio driver bootstrap functions */

static int
Audio_Available(void)
{
    int fd;
    int available;

    available = 0;
    fd = SDL_OpenAudioPath(NULL, 0, OPEN_FLAGS, 0);
    if (fd >= 0) {
        available = 1;
        close(fd);
    }
    return (available);
}

static void
Audio_DeleteDevice(SDL_AudioDevice * device)
{
    SDL_free(device->hidden);
    SDL_free(device);
}

static SDL_AudioDevice *
Audio_CreateDevice(int devindex)
{
    SDL_AudioDevice *this;

    /* Initialize all variables that we clean on shutdown */
    this = (SDL_AudioDevice *) SDL_malloc(sizeof(SDL_AudioDevice));
    if (this) {
        SDL_memset(this, 0, (sizeof *this));
        this->hidden = (struct SDL_PrivateAudioData *)
            SDL_malloc((sizeof *this->hidden));
    }
    if ((this == NULL) || (this->hidden == NULL)) {
        SDL_OutOfMemory();
        if (this)
            SDL_free(this);
        return (0);
    }
    SDL_memset(this->hidden, 0, (sizeof *this->hidden));
    audio_fd = -1;

    /* Set the function pointers */
    this->OpenAudio = OBSD_OpenAudio;
    this->WaitAudio = OBSD_WaitAudio;
    this->PlayAudio = OBSD_PlayAudio;
    this->GetAudioBuf = OBSD_GetAudioBuf;
    this->CloseAudio = OBSD_CloseAudio;

    this->free = Audio_DeleteDevice;

    return this;
}

AudioBootStrap BSD_AUDIO_bootstrap = {
    BSD_AUDIO_DRIVER_NAME, BSD_AUDIO_DRIVER_DESC,
    Audio_Available, Audio_CreateDevice, 0
};

/* This function waits until it is possible to write a full sound buffer */
static void
OBSD_WaitAudio(_THIS)
{
#ifndef USE_BLOCKING_WRITES     /* Not necessary when using blocking writes */
    /* See if we need to use timed audio synchronization */
    if (frame_ticks) {
        /* Use timer for general audio synchronization */
        Sint32 ticks;

        ticks = ((Sint32) (next_frame - SDL_GetTicks())) - FUDGE_TICKS;
        if (ticks > 0) {
            SDL_Delay(ticks);
        }
    } else {
        /* Use select() for audio synchronization */
        fd_set fdset;
        struct timeval timeout;

        FD_ZERO(&fdset);
        FD_SET(audio_fd, &fdset);
        timeout.tv_sec = 10;
        timeout.tv_usec = 0;
#ifdef DEBUG_AUDIO
        fprintf(stderr, "Waiting for audio to get ready\n");
#endif
        if (select(audio_fd + 1, NULL, &fdset, NULL, &timeout) <= 0) {
            const char *message =
                "Audio timeout - buggy audio driver? (disabled)";
            /* In general we should never print to the screen,
               but in this case we have no other way of letting
               the user know what happened.
             */
            fprintf(stderr, "SDL: %s\n", message);
            this->enabled = 0;
            /* Don't try to close - may hang */
            audio_fd = -1;
#ifdef DEBUG_AUDIO
            fprintf(stderr, "Done disabling audio\n");
#endif
        }
#ifdef DEBUG_AUDIO
        fprintf(stderr, "Ready!\n");
#endif
    }
#endif /* !USE_BLOCKING_WRITES */
}

static void
OBSD_PlayAudio(_THIS)
{
    int written, p = 0;

    /* Write the audio data, checking for EAGAIN on broken audio drivers */
    do {
        written = write(audio_fd, &mixbuf[p], mixlen - p);
        if (written > 0)
            p += written;
        if (written == -1 && errno != 0 && errno != EAGAIN && errno != EINTR) {
            /* Non recoverable error has occurred. It should be reported!!! */
            perror("audio");
            break;
        }

        if (p < written
            || ((written < 0) && ((errno == 0) || (errno == EAGAIN)))) {
            SDL_Delay(1);       /* Let a little CPU time go by */
        }
    }
    while (p < written);

    /* If timer synchronization is enabled, set the next write frame */
    if (frame_ticks) {
        next_frame += frame_ticks;
    }

    /* If we couldn't write, assume fatal error for now */
    if (written < 0) {
        this->enabled = 0;
    }
#ifdef DEBUG_AUDIO
    fprintf(stderr, "Wrote %d bytes of audio data\n", written);
#endif
}

static Uint8 *
OBSD_GetAudioBuf(_THIS)
{
    return (mixbuf);
}

static void
OBSD_CloseAudio(_THIS)
{
    if (mixbuf != NULL) {
        SDL_FreeAudioMem(mixbuf);
        mixbuf = NULL;
    }
    if (audio_fd >= 0) {
        close(audio_fd);
        audio_fd = -1;
    }
}

#ifdef DEBUG_AUDIO
void
OBSD_Status(_THIS)
{
    audio_info_t info;

    if (ioctl(audio_fd, AUDIO_GETINFO, &info) < 0) {
        fprintf(stderr, "AUDIO_GETINFO failed.\n");
        return;
    }

    fprintf(stderr, "\n"
            "[play/record info]\n"
            "buffer size	:   %d bytes\n"
            "sample rate	:   %i Hz\n"
            "channels	:   %i\n"
            "precision	:   %i-bit\n"
            "encoding	:   0x%x\n"
            "seek		:   %i\n"
            "sample count	:   %i\n"
            "EOF count	:   %i\n"
            "paused		:   %s\n"
            "error occured	:   %s\n"
            "waiting		:   %s\n"
            "active		:   %s\n"
            "",
            info.
            play.
            buffer_size,
            info.
            play.
            sample_rate,
            info.
            play.
            channels,
            info.
            play.
            precision,
            info.
            play.
            encoding,
            info.
            play.
            seek,
            info.
            play.
            samples,
            info.
            play.
            eof,
            info.
            play.
            pause
            ?
            "yes"
            :
            "no",
            info.
            play.
            error
            ?
            "yes"
            :
            "no",
            info.
            play.waiting ? "yes" : "no", info.play.active ? "yes" : "no");

    fprintf(stderr, "\n"
            "[audio info]\n"
            "monitor_gain	:   %i\n"
            "hw block size	:   %d bytes\n"
            "hi watermark	:   %i\n"
            "lo watermark	:   %i\n"
            "audio mode	:   %s\n"
            "",
            info.monitor_gain,
            info.blocksize,
            info.hiwat, info.lowat,
            (info.mode == AUMODE_PLAY) ? "PLAY"
            : (info.mode = AUMODE_RECORD) ? "RECORD"
            : (info.mode == AUMODE_PLAY_ALL ? "PLAY_ALL" : "?"));
}
#endif /* DEBUG_AUDIO */

static int
OBSD_OpenAudio(_THIS, SDL_AudioSpec * spec)
{
    char audiodev[64];
    SDL_AudioFormat format;
    audio_info_t info;

    AUDIO_INITINFO(&info);

    /* Calculate the final parameters for this audio specification */
    SDL_CalculateAudioSpec(spec);

#ifdef USE_TIMER_SYNC
    frame_ticks = 0.0;
#endif

    /* Open the audio device */
    audio_fd = SDL_OpenAudioPath(audiodev, sizeof(audiodev), OPEN_FLAGS, 0);
    if (audio_fd < 0) {
        SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno));
        return (-1);
    }

    /* Set to play mode */
    info.mode = AUMODE_PLAY;
    if (ioctl(audio_fd, AUDIO_SETINFO, &info) < 0) {
        SDL_SetError("Couldn't put device into play mode");
        return (-1);
    }

    mixbuf = NULL;
    AUDIO_INITINFO(&info);
    for (format = SDL_FirstAudioFormat(spec->format);
         format; format = SDL_NextAudioFormat()) {
        switch (format) {
        case AUDIO_U8:
            info.play.encoding = AUDIO_ENCODING_ULINEAR;
            info.play.precision = 8;
            break;
        case AUDIO_S8:
            info.play.encoding = AUDIO_ENCODING_SLINEAR;
            info.play.precision = 8;
            break;
        case AUDIO_S16LSB:
            info.play.encoding = AUDIO_ENCODING_SLINEAR_LE;
            info.play.precision = 16;
            break;
        case AUDIO_S16MSB:
            info.play.encoding = AUDIO_ENCODING_SLINEAR_BE;
            info.play.precision = 16;
            break;
        case AUDIO_U16LSB:
            info.play.encoding = AUDIO_ENCODING_ULINEAR_LE;
            info.play.precision = 16;
            break;
        case AUDIO_U16MSB:
            info.play.encoding = AUDIO_ENCODING_ULINEAR_BE;
            info.play.precision = 16;
            break;
        default:
            continue;
        }
        if (ioctl(audio_fd, AUDIO_SETINFO, &info) == 0)
            break;
    }

    if (!format) {
        SDL_SetError("No supported encoding for 0x%x", spec->format);
        return (-1);
    }

    spec->format = format;

    AUDIO_INITINFO(&info);
    info.play.channels = spec->channels;
    if (ioctl(audio_fd, AUDIO_SETINFO, &info) == -1)
        spec->channels = 1;
    AUDIO_INITINFO(&info);
    info.play.sample_rate = spec->freq;
    info.blocksize = spec->size;
    info.hiwat = 5;
    info.lowat = 3;
    (void) ioctl(audio_fd, AUDIO_SETINFO, &info);
    (void) ioctl(audio_fd, AUDIO_GETINFO, &info);
    spec->freq = info.play.sample_rate;
    /* Allocate mixing buffer */
    mixlen = spec->size;
    mixbuf = (Uint8 *) SDL_AllocAudioMem(mixlen);
    if (mixbuf == NULL) {
        return (-1);
    }
    SDL_memset(mixbuf, spec->silence, spec->size);

    /* Get the parent process id (we're the parent of the audio thread) */
    parent = getpid();

#ifdef DEBUG_AUDIO
    OBSD_Status(this);
#endif

    /* We're ready to rock and roll. :-) */
    return (0);
}

/* vi: set ts=4 sw=4 expandtab: */