src/audio/bsd/SDL_bsdaudio.c

/*
    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: */