/*

SDL - Simple DirectMedia Layer

Copyright (C) 1997, 1998, 1999, 2000, 2001 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@devolution.com

*/

#ifdef SAVE_RCSID

static char rcsid =

"@(#) $Id$";

#endif

/* Allow access to a raw mixing buffer */

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <unistd.h>

#include <fcntl.h>

#include <signal.h>

#include <sys/time.h>

#include <sys/ioctl.h>

#include <sys/stat.h>

#include <sys/soundcard.h>

#include "SDL_audio.h"

#include "SDL_error.h"

#include "SDL_audiomem.h"

#include "SDL_audio_c.h"

#include "SDL_timer.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 USE_BLOCKING_WRITES

#ifdef USE_BLOCKING_WRITES

#define OPEN_FLAGS O_WRONLY

#else

#define OPEN_FLAGS (O_WRONLY|O_NONBLOCK)

#endif

/* 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)

{

free(device->hidden);

free(device);

}

static SDL_AudioDevice *Audio_CreateDevice(int devindex)

{

SDL_AudioDevice *this;

/* Initialize all variables that we clean on shutdown */

this = (SDL_AudioDevice *)malloc(sizeof(SDL_AudioDevice));

if ( this ) {

memset(this, 0, (sizeof *this));

this->hidden = (struct SDL_PrivateAudioData *)

malloc((sizeof *this->hidden));

}

if ( (this == NULL) || (this->hidden == NULL) ) {

SDL_OutOfMemory();

if ( this ) {

free(this);

}

return(0);

}

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)

{

/* 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;

}

}

}

#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 DSP_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 *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_ReopenAudio(_THIS, const char *audiodev, int format,

SDL_AudioSpec *spec)

{

int frag_spec;

int value;

/* Close and then reopen the audio device */

close(audio_fd);

audio_fd = open(audiodev, O_WRONLY, 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);

}

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 ) {

fprintf(stderr, "Warning: Couldn't set audio fragment size\n");

}

#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

/* 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 the number of channels of output */

value = spec->channels;

#ifdef SNDCTL_DSP_CHANNELS

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

#endif

value = (spec->channels > 1);

ioctl(audio_fd, SNDCTL_DSP_STEREO, &value);

value = (value ? 2 : 1);

#ifdef SNDCTL_DSP_CHANNELS

}

#endif

if ( value != spec->channels ) {

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

return(-1);

}

/* Set the DSP frequency */

value = spec->freq;

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

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

return(-1);

}

spec->freq = value;

/* We successfully re-opened the audio */

return(0);

}

static int DSP_OpenAudio(_THIS, SDL_AudioSpec *spec)

{

char audiodev[1024];

int format;

int value;

Uint16 test_format;

/* 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);

}

mixbuf = NULL;

/* 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:

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 the number of channels of output */

value = spec->channels;

#ifdef SNDCTL_DSP_CHANNELS

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

#endif

value = (spec->channels > 1);

ioctl(audio_fd, SNDCTL_DSP_STEREO, &value);

value = (value ? 2 : 1);

#ifdef SNDCTL_DSP_CHANNELS

}

#endif

spec->channels = value;

/* 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 ( DSP_ReopenAudio(this, audiodev, format, spec) < 0 ) {

/* Error is set by DSP_ReopenAudio() */

return(-1);

}

/* Allocate mixing buffer */

mixlen = spec->size;

mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen);

if ( mixbuf == NULL ) {

return(-1);

}

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

#ifndef USE_BLOCKING_WRITES

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

{ char *workaround;

workaround = getenv("SDL_DSP_NOSELECT");

if ( workaround ) {

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

next_frame = SDL_GetTicks()+frame_ticks;

}

}

#endif /* !USE_BLOCKING_WRITES */

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

parent = getpid();

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

return(0);

}