/*

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

*/

/* 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>

#ifdef OSS_USE_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; (0x01<<frag_spec) < spec->size; ++frag_spec );

if ( (0x01<<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);

}