/*

SDL - Simple DirectMedia Layer

This library is free software; you can redistribute it and/or

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

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

/* Allow access to a raw mixing buffer */

#include <stdio.h>

#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 */

#ifndef MAP_FAILED

#define MAP_FAILED ((Uint8 *)-1)

#endif

#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 */

}

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

SDL_OutOfMemory();

if ( this ) {

}

return(0);

}

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;

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;

Uint16 test_format;

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:

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);

}

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

{ char *workaround;

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);

}