src/audio/arts/SDL_artsaudio.c

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

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

/* Allow access to a raw mixing buffer */

#include "SDL_timer.h"
#include "SDL_audio.h"
#include "../SDL_audiomem.h"
#include "../SDL_audio_c.h"
#include "SDL_artsaudio.h"

#ifdef SDL_AUDIO_DRIVER_ARTS_DYNAMIC
#include "SDL_name.h"
#include "SDL_loadso.h"
#else
#define SDL_NAME(X)	X
#endif

/* The tag name used by artsc audio */
#define ARTS_DRIVER_NAME         "arts"

#ifdef SDL_AUDIO_DRIVER_ARTS_DYNAMIC

static const char *arts_library = SDL_AUDIO_DRIVER_ARTS_DYNAMIC;
static void *arts_handle = NULL;

/* !!! FIXME: I hate this SDL_NAME clutter...it makes everything so messy! */
static int (*SDL_NAME(arts_init)) (void);
static void (*SDL_NAME(arts_free)) (void);
static arts_stream_t(*SDL_NAME(arts_play_stream)) (int rate, int bits,
                                                   int channels,
                                                   const char *name);
static int (*SDL_NAME(arts_stream_set)) (arts_stream_t s,
                                         arts_parameter_t param, int value);
static int (*SDL_NAME(arts_stream_get)) (arts_stream_t s,
                                         arts_parameter_t param);
static int (*SDL_NAME(arts_write)) (arts_stream_t s, const void *buffer,
                                    int count);
static void (*SDL_NAME(arts_close_stream)) (arts_stream_t s);
static void (*SDL_NAME(arts_close_stream)) (arts_stream_t s);
static const char *(*SDL_NAME(arts_error_text)) (int errorcode);

#define SDL_ARTS_SYM(x) { #x, (void **) (char *) &SDL_NAME(x) }
static struct
{
    const char *name;
    void **func;
} arts_functions[] = {
    SDL_ARTS_SYM(arts_init),
    SDL_ARTS_SYM(arts_free),
    SDL_ARTS_SYM(arts_play_stream),
    SDL_ARTS_SYM(arts_stream_set),
    SDL_ARTS_SYM(arts_stream_get),
    SDL_ARTS_SYM(arts_write),
    SDL_ARTS_SYM(arts_close_stream),
    SDL_ARTS_SYM(arts_error_text),
};
#undef SDL_ARTS_SYM

static void
UnloadARTSLibrary()
{
    if (arts_handle != NULL) {
        SDL_UnloadObject(arts_handle);
        arts_handle = NULL;
    }
}

static int
LoadARTSLibrary(void)
{
    int i, retval = -1;

    if (arts_handle == NULL) {
        arts_handle = SDL_LoadObject(arts_library);
        if (arts_handle != NULL) {
            retval = 0;
            for (i = 0; i < SDL_arraysize(arts_functions); ++i) {
                *arts_functions[i].func =
                    SDL_LoadFunction(arts_handle, arts_functions[i].name);
                if (!*arts_functions[i].func) {
                    retval = -1;
                    UnloadARTSLibrary();
                    break;
                }
            }
        }
    }

    return retval;
}

#else

static void
UnloadARTSLibrary()
{
    return;
}

static int
LoadARTSLibrary(void)
{
    return 0;
}

#endif /* SDL_AUDIO_DRIVER_ARTS_DYNAMIC */

/* This function waits until it is possible to write a full sound buffer */
static void
ARTS_WaitDevice(_THIS)
{
    Sint32 ticks;

    /* Check to see if the thread-parent process is still alive */
    {
        static int cnt = 0;
        /* Note that this only works with thread implementations
           that use a different process id for each thread.
         */
        /* Check every 10 loops */
        if (this->hidden->parent && (((++cnt) % 10) == 0)) {
            if (kill(this->hidden->parent, 0) < 0) {
                this->enabled = 0;
            }
        }
    }

    /* Use timer for general audio synchronization */
    ticks = ((Sint32) (this->hidden->next_frame-SDL_GetTicks())) - FUDGE_TICKS;
    if (ticks > 0) {
        SDL_Delay(ticks);
    }
}

static void
ARTS_PlayDevice(_THIS)
{
    /* Write the audio data */
    int written = SDL_NAME(arts_write) (
                        this->hidden->stream,
                        this->hidden->mixbuf,
                        this->hidden->mixlen);

    /* If timer synchronization is enabled, set the next write frame */
    if (this->hidden->frame_ticks) {
        this->hidden->next_frame += this->hidden->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 void
ARTS_WaitDone(_THIS)
{
    /* !!! FIXME: camp here until buffer drains... SDL_Delay(???); */
}


static Uint8 *
ARTS_GetDeviceBuf(_THIS)
{
    return (this->hidden->mixbuf);
}


static void
ARTS_CloseDevice(_THIS)
{
    if (this->hidden != NULL) {
        if (this->hidden->mixbuf != NULL) {
            SDL_FreeAudioMem(this->hidden->mixbuf);
            this->hidden->mixbuf = NULL;
        }
        if (this->hidden->stream) {
            SDL_NAME(arts_close_stream) (this->hidden->stream);
            this->hidden->stream = 0;
        }
        SDL_NAME(arts_free) ();
        SDL_free(this->hidden);
        this->hidden = NULL;
    }
}


static int
ARTS_OpenDevice(_THIS, const char *devname, int iscapture)
{
    int rc = 0;
    int bits = 0, frag_spec = 0;
    SDL_AudioFormat test_format = 0, format = 0;

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

    /* Try for a closest match on audio format */
    for (test_format = SDL_FirstAudioFormat(this->spec.format);
         !format && test_format;) {
#ifdef DEBUG_AUDIO
        fprintf(stderr, "Trying format 0x%4.4x\n", test_format);
#endif
        switch (test_format) {
        case AUDIO_U8:
            bits = 8;
            format = 1;
            break;
        case AUDIO_S16LSB:
            bits = 16;
            format = 1;
            break;
        default:
            format = 0;
            break;
        }
        if (!format) {
            test_format = SDL_NextAudioFormat();
        }
    }
    if (format == 0) {
        ARTS_CloseDevice(this);
        SDL_SetError("Couldn't find any hardware audio formats");
        return 0;
    }
    this->spec.format = test_format;

    if ((rc = SDL_NAME(arts_init) ()) != 0) {
        ARTS_CloseDevice(this);
        SDL_SetError( "Unable to initialize ARTS: %s",
                      SDL_NAME(arts_error_text)(rc) );
        return 0;
    }
    this->hidden->stream = SDL_NAME(arts_play_stream) (
                                            this->spec.freq,
                                            bits, this->spec.channels,
                                            "SDL");

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

    /* Determine the power of two of the fragment size */
    for (frag_spec = 0; (0x01 << frag_spec) < this->spec.size; ++frag_spec);
    if ((0x01 << frag_spec) != this->spec.size) {
        ARTS_CloseDevice(this);
        SDL_SetError("Fragment size must be a power of two");
        return 0;
    }
    frag_spec |= 0x00020000;    /* two fragments, for low latency */

#ifdef ARTS_P_PACKET_SETTINGS
    SDL_NAME(arts_stream_set) (this->hidden->stream,
                                ARTS_P_PACKET_SETTINGS, frag_spec);
#else
    SDL_NAME(arts_stream_set) (this->hidden->stream, ARTS_P_PACKET_SIZE,
                               frag_spec & 0xffff);
    SDL_NAME(arts_stream_set) (this->hidden->stream, ARTS_P_PACKET_COUNT,
                               frag_spec >> 16);
#endif
    this->spec.size = SDL_NAME(arts_stream_get) (this->hidden->stream,
                                                 ARTS_P_PACKET_SIZE);

    /* Allocate mixing buffer */
    this->hidden->mixlen = this->spec.size;
    this->hidden->mixbuf = (Uint8 *) SDL_AllocAudioMem(this->hidden->mixlen);
    if (this->hidden->mixbuf == NULL) {
        ARTS_CloseDevice(this);
        SDL_OutOfMemory();
        return 0;
    }
    SDL_memset(this->hidden->mixbuf, this->spec.silence, this->spec.size);

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

    /* We're ready to rock and roll. :-) */
    return 1;
}


static void
ARTS_Deinitialize(void)
{
    UnloadARTSLibrary();
}


static int
ARTS_Init(SDL_AudioDriverImpl *impl)
{
    if (LoadARTSLibrary() < 0) {
        return 0;
    } else {
        if (SDL_NAME(arts_init) () != 0) {
            UnloadARTSLibrary();
            SDL_SetError("ARTS: arts_init failed (no audio server?)");
            return 0;
        }

        /* Play a stream so aRts doesn't crash */
        arts_stream_t stream;
        stream = SDL_NAME(arts_play_stream) (44100, 16, 2, "SDL");
        SDL_NAME(arts_write) (stream, "", 0);
        SDL_NAME(arts_close_stream) (stream);
        SDL_NAME(arts_free) ();
    }

    /* Set the function pointers */
    impl->OpenDevice = ARTS_OpenDevice;
    impl->PlayDevice = ARTS_PlayDevice;
    impl->WaitDevice = ARTS_WaitDevice;
    impl->GetDeviceBuf = ARTS_GetDeviceBuf;
    impl->CloseDevice = ARTS_CloseDevice;
    impl->WaitDone = ARTS_WaitDone;
    impl->Deinitialize = ARTS_Deinitialize;
    impl->OnlyHasDefaultOutputDevice = 1;

    return 1;
}


AudioBootStrap ARTS_bootstrap = {
    ARTS_DRIVER_NAME, "Analog RealTime Synthesizer", ARTS_Init, 0
};

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