/*

    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

    Modified in Oct 2004 by Hannu Savolainen 

    hannu@opensound.com

*/

#include "SDL_config.h"

/* Allow access to a raw mixing buffer */

#include <stdio.h>              /* For perror() */

#include <string.h>             /* For strerror() */

#include <errno.h>

#include <unistd.h>

#include <fcntl.h>

#include <signal.h>

#include <sys/time.h>

#include <sys/ioctl.h>

#include <sys/stat.h>

#if SDL_AUDIO_DRIVER_OSS_SOUNDCARD_H

/* This is installed on some systems */

#include <soundcard.h>

#else

/* This is recommended by OSS */

#include <sys/soundcard.h>

#endif

#include "SDL_timer.h"

#include "SDL_audio.h"

#include "../SDL_audiomem.h"

#include "../SDL_audio_c.h"

#include "../SDL_audiodev_c.h"

#include "SDL_dspaudio.h"

/* The tag name used by DSP audio */

#define DSP_DRIVER_NAME         "dsp"

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

#define OPEN_FLAGS	(O_WRONLY|O_NONBLOCK)

/* Audio driver functions */

static int DSP_OpenAudio(_THIS, SDL_AudioSpec * spec);

static void DSP_WaitAudio(_THIS);

static void DSP_PlayAudio(_THIS);

static Uint8 *DSP_GetAudioBuf(_THIS);

static void DSP_CloseAudio(_THIS);

/* 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 = DSP_OpenAudio;

    this->WaitAudio = DSP_WaitAudio;

    this->PlayAudio = DSP_PlayAudio;

    this->GetAudioBuf = DSP_GetAudioBuf;

    this->CloseAudio = DSP_CloseAudio;

    this->free = Audio_DeleteDevice;

    return this;

}

AudioBootStrap DSP_bootstrap = {

    DSP_DRIVER_NAME, "OSS /dev/dsp standard audio",

    Audio_Available, Audio_CreateDevice

};

/* This function waits until it is possible to write a full sound buffer */

static void

DSP_WaitAudio(_THIS)

{

    /* Not needed at all since OSS handles waiting automagically */

}

static void

DSP_PlayAudio(_THIS)

{

    if (write(audio_fd, mixbuf, mixlen) == -1) {

        perror("Audio write");

        this->enabled = 0;

    }

#ifdef DEBUG_AUDIO

    fprintf(stderr, "Wrote %d bytes of audio data\n", mixlen);

#endif

}

static Uint8 *

DSP_GetAudioBuf(_THIS)

{

    return (mixbuf);

}

static void

DSP_CloseAudio(_THIS)

{

    if (mixbuf != NULL) {

        SDL_FreeAudioMem(mixbuf);

        mixbuf = NULL;

    }

    if (audio_fd >= 0) {

        close(audio_fd);

        audio_fd = -1;

    }

}

static int

DSP_OpenAudio(_THIS, SDL_AudioSpec * spec)

{

    char audiodev[1024];

    int format;

    int value;

    int frag_spec;

    Uint16 test_format;

    /* 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);

    }

    mixbuf = NULL;

    /* Make the file descriptor use blocking writes with fcntl() */

    {

        long flags;

        flags = fcntl(audio_fd, F_GETFL);

        flags &= ~O_NONBLOCK;

        if (fcntl(audio_fd, F_SETFL, flags) < 0) {

            SDL_SetError("Couldn't set audio blocking mode");

            DSP_CloseAudio(this);

            return (-1);

        }

    }

    /* Get a list of supported hardware formats */

    if (ioctl(audio_fd, SNDCTL_DSP_GETFMTS, &value) < 0) {

        perror("SNDCTL_DSP_GETFMTS");

        SDL_SetError("Couldn't get audio format list");

        DSP_CloseAudio(this);

        return (-1);

    }

    /* Try for a closest match on audio format */

    format = 0;

    for (test_format = SDL_FirstAudioFormat(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:

            if (value & AFMT_U8) {

                format = AFMT_U8;

            }

            break;

        case AUDIO_S16LSB:

            if (value & AFMT_S16_LE) {

                format = AFMT_S16_LE;

            }

            break;

        case AUDIO_S16MSB:

            if (value & AFMT_S16_BE) {

                format = AFMT_S16_BE;

            }

            break;

#if 0

/*

 * These formats are not used by any real life systems so they are not 

 * needed here.

 */

        case AUDIO_S8:

            if (value & AFMT_S8) {

                format = AFMT_S8;

            }

            break;

        case AUDIO_U16LSB:

            if (value & AFMT_U16_LE) {

                format = AFMT_U16_LE;

            }

            break;

        case AUDIO_U16MSB:

            if (value & AFMT_U16_BE) {

                format = AFMT_U16_BE;

            }

            break;

#endif

        default:

            format = 0;

            break;

        }

        if (!format) {

            test_format = SDL_NextAudioFormat();

        }

    }

    if (format == 0) {

        SDL_SetError("Couldn't find any hardware audio formats");

        DSP_CloseAudio(this);

        return (-1);

    }

    spec->format = test_format;

    /* Set the audio format */

    value = format;

    if ((ioctl(audio_fd, SNDCTL_DSP_SETFMT, &value) < 0) || (value != format)) {

        perror("SNDCTL_DSP_SETFMT");

        SDL_SetError("Couldn't set audio format");

        DSP_CloseAudio(this);

        return (-1);

    }

    /* Set the number of channels of output */

    value = spec->channels;

    if (ioctl(audio_fd, SNDCTL_DSP_CHANNELS, &value) < 0) {

        perror("SNDCTL_DSP_CHANNELS");

        SDL_SetError("Cannot set the number of channels");

        DSP_CloseAudio(this);

        return (-1);

    }

    spec->channels = value;

    /* Set the DSP frequency */

    value = spec->freq;

    if (ioctl(audio_fd, SNDCTL_DSP_SPEED, &value) < 0) {

        perror("SNDCTL_DSP_SPEED");

        SDL_SetError("Couldn't set audio frequency");

        DSP_CloseAudio(this);

        return (-1);

    }

    spec->freq = value;

    /* Calculate the final parameters for this audio specification */

    SDL_CalculateAudioSpec(spec);

    /* Determine the power of two of the fragment size */

    for (frag_spec = 0; (0x01U << frag_spec) < spec->size; ++frag_spec);

    if ((0x01U << frag_spec) != spec->size) {

        SDL_SetError("Fragment size must be a power of two");

        DSP_CloseAudio(this);

        return (-1);

    }

    frag_spec |= 0x00020000;    /* two fragments, for low latency */

    /* Set the audio buffering parameters */

#ifdef DEBUG_AUDIO

    fprintf(stderr, "Requesting %d fragments of size %d\n",

            (frag_spec >> 16), 1 << (frag_spec & 0xFFFF));

#endif

    if (ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &frag_spec) < 0) {

        perror("SNDCTL_DSP_SETFRAGMENT");

    }

#ifdef DEBUG_AUDIO

    {

        audio_buf_info info;

        ioctl(audio_fd, SNDCTL_DSP_GETOSPACE, &info);

        fprintf(stderr, "fragments = %d\n", info.fragments);

        fprintf(stderr, "fragstotal = %d\n", info.fragstotal);

        fprintf(stderr, "fragsize = %d\n", info.fragsize);

        fprintf(stderr, "bytes = %d\n", info.bytes);

    }

#endif

    /* Allocate mixing buffer */

    mixlen = spec->size;

    mixbuf = (Uint8 *) SDL_AllocAudioMem(mixlen);

    if (mixbuf == NULL) {

        DSP_CloseAudio(this);

        return (-1);

    }

    SDL_memset(mixbuf, spec->silence, spec->size);

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

    parent = getpid();

    /* We're ready to rock and roll. :-) */

    return (0);

}

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