/*

    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 <stdio.h>

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

#include <errno.h>

#include <unistd.h>

#include <fcntl.h>

#include <signal.h>

#include <sys/types.h>

#include <sys/time.h>

#include <sys/ioctl.h>

#include <sys/stat.h>

#include <sys/mman.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

#ifndef MAP_FAILED

#define MAP_FAILED	((Uint8 *)-1)

#endif

#include "SDL_timer.h"

#include "SDL_audio.h"

#include "../SDL_audio_c.h"

#include "../SDL_audiodev_c.h"

#include "SDL_dmaaudio.h"

/* The tag name used by DMA audio */

#define DMA_DRIVER_NAME         "dma"

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

#define OPEN_FLAGS	(O_RDWR|O_NONBLOCK)

/* Audio driver functions */

static int DMA_OpenAudio(_THIS, SDL_AudioSpec * spec);

static void DMA_WaitAudio(_THIS);

static void DMA_PlayAudio(_THIS);

static Uint8 *DMA_GetAudioBuf(_THIS);

static void DMA_CloseAudio(_THIS);

/* Audio driver bootstrap functions */

static int

Audio_Available(void)

{

    int available;

    int fd;

    available = 0;

    fd = SDL_OpenAudioPath(NULL, 0, OPEN_FLAGS, 0);

    if (fd >= 0) {

        int caps;

        struct audio_buf_info info;

        if ((ioctl(fd, SNDCTL_DSP_GETCAPS, &caps) == 0) &&

            (caps & DSP_CAP_TRIGGER) && (caps & DSP_CAP_MMAP) &&

            (ioctl(fd, SNDCTL_DSP_GETOSPACE, &info) == 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 = DMA_OpenAudio;

    this->WaitAudio = DMA_WaitAudio;

    this->PlayAudio = DMA_PlayAudio;

    this->GetAudioBuf = DMA_GetAudioBuf;

    this->CloseAudio = DMA_CloseAudio;

    this->free = Audio_DeleteDevice;

    return this;

}

AudioBootStrap DMA_bootstrap = {

    DMA_DRIVER_NAME, "OSS /dev/dsp DMA audio",

    Audio_Available, Audio_CreateDevice

};

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

static void

DMA_WaitAudio(_THIS)

{

    fd_set fdset;

    /* 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.

         */

        if (parent && (((++cnt) % 10) == 0)) {  /* Check every 10 loops */

            if (kill(parent, 0) < 0) {

                this->enabled = 0;

            }

        }

    }

    /* 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 */

        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 =

#ifdef AUDIO_OSPACE_HACK

                "Audio timeout - buggy audio driver? (trying ospace)";

#else

                "Audio timeout - buggy audio driver? (disabled)";

#endif

            /* 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);

#ifdef AUDIO_OSPACE_HACK

            /* We may be able to use GET_OSPACE trick */

            frame_ticks = (float) (this->spec->samples * 1000) /

                this->spec->freq;

            next_frame = SDL_GetTicks() + frame_ticks;

#else

            this->enabled = 0;

            /* Don't try to close - may hang */

            audio_fd = -1;

#ifdef DEBUG_AUDIO

            fprintf(stderr, "Done disabling audio\n");

#endif

#endif /* AUDIO_OSPACE_HACK */

        }

#ifdef DEBUG_AUDIO

        fprintf(stderr, "Ready!\n");

#endif

    }

}

static void

DMA_PlayAudio(_THIS)

{

    /* If timer synchronization is enabled, set the next write frame */

    if (frame_ticks) {

        next_frame += frame_ticks;

    }

    return;

}

static Uint8 *

DMA_GetAudioBuf(_THIS)

{

    count_info info;

    int playing;

    int filling;

    /* Get number of blocks, looping if we're not using select() */

    do {

        if (ioctl(audio_fd, SNDCTL_DSP_GETOPTR, &info) < 0) {

            /* Uh oh... */

            this->enabled = 0;

            return (NULL);

        }

    }

    while (frame_ticks && (info.blocks < 1));

#ifdef DEBUG_AUDIO

    if (info.blocks > 1) {

        printf("Warning: audio underflow (%d frags)\n", info.blocks - 1);

    }

#endif

    playing = info.ptr / this->spec.size;

    filling = (playing + 1) % num_buffers;

    return (dma_buf + (filling * this->spec.size));

}

static void

DMA_CloseAudio(_THIS)

{

    if (dma_buf != NULL) {

        munmap(dma_buf, dma_len);

        dma_buf = NULL;

    }

    if (audio_fd >= 0) {

        close(audio_fd);

        audio_fd = -1;

    }

}

static int

DMA_ReopenAudio(_THIS, const char *audiodev, int format, int stereo,

                SDL_AudioSpec * spec)

{

    int frag_spec;

    int value;

    /* Close and then reopen the audio device */

    close(audio_fd);

    audio_fd = open(audiodev, O_RDWR, 0);

    if (audio_fd < 0) {

        SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno));

        return (-1);

    }

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

    SDL_CalculateAudioSpec(spec);

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

    for (frag_spec = 0; (0x01 << frag_spec) < spec->size; ++frag_spec);

    if ((0x01 << frag_spec) != spec->size) {

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

        return (-1);

    }

    /* Set the audio buffering parameters */

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

        SDL_SetError("Couldn't set audio fragment spec");

        return (-1);

    }

    /* Set the audio format */

    value = format;

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

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

        return (-1);

    }

    /* Set mono or stereo audio */

    value = (spec->channels > 1);

    if ((ioctl(audio_fd, SNDCTL_DSP_STEREO, &stereo) < 0) ||

        (value != stereo)) {

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

        return (-1);

    }

    /* Set the DSP frequency */

    value = spec->freq;

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

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

        return (-1);

    }

    spec->freq = value;

    /* We successfully re-opened the audio */

    return (0);

}

static int

DMA_OpenAudio(_THIS, SDL_AudioSpec * spec)

{

    char audiodev[1024];

    int format;

    int stereo;

    int value;

    struct audio_buf_info info;

    /* Reset the timer synchronization flag */

    frame_ticks = 0.0;

    /* 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);

    }

    dma_buf = NULL;

    ioctl(audio_fd, SNDCTL_DSP_RESET, 0);

    /* Get a list of supported hardware formats */

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

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

        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_S8:

            if (value & AFMT_S8) {

                format = AFMT_S8;

            }

            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;

        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;

        default:

            format = 0;

            break;

        }

        if (!format) {

            test_format = SDL_NextAudioFormat();

        }

    }

    if (format == 0) {

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

        return (-1);

    }

    spec->format = test_format;

    /* Set the audio format */

    value = format;

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

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

        return (-1);

    }

    /* Set mono or stereo audio (currently only two channels supported) */

    stereo = (spec->channels > 1);

    ioctl(audio_fd, SNDCTL_DSP_STEREO, &stereo);

    if (stereo) {

        spec->channels = 2;

    } else {

        spec->channels = 1;

    }

    /* Because some drivers don't allow setting the buffer size

       after setting the format, we must re-open the audio device

       once we know what format and channels are supported

     */

    if (DMA_ReopenAudio(this, audiodev, format, stereo, spec) < 0) {

        /* Error is set by DMA_ReopenAudio() */

        return (-1);

    }

    /* Memory map the audio buffer */

    if (ioctl(audio_fd, SNDCTL_DSP_GETOSPACE, &info) < 0) {

        SDL_SetError("Couldn't get OSPACE parameters");

        return (-1);

    }

    spec->size = info.fragsize;

    spec->samples = spec->size / ((spec->format & 0xFF) / 8);

    spec->samples /= spec->channels;

    num_buffers = info.fragstotal;

    dma_len = num_buffers * spec->size;

    dma_buf = (Uint8 *) mmap(NULL, dma_len, PROT_WRITE, MAP_SHARED,

                             audio_fd, 0);

    if (dma_buf == MAP_FAILED) {

        SDL_SetError("DMA memory map failed");

        dma_buf = NULL;

        return (-1);

    }

    SDL_memset(dma_buf, spec->silence, dma_len);

    /* Check to see if we need to use select() workaround */

    {

        char *workaround;

        workaround = SDL_getenv("SDL_DSP_NOSELECT");

        if (workaround) {

            frame_ticks = (float) (spec->samples * 1000) / spec->freq;

            next_frame = SDL_GetTicks() + frame_ticks;

        }

    }

    /* Trigger audio playback */

    value = 0;

    ioctl(audio_fd, SNDCTL_DSP_SETTRIGGER, &value);

    value = PCM_ENABLE_OUTPUT;

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

        SDL_SetError("Couldn't trigger audio output");

        return (-1);

    }

    /* 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: */