/*

    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>

/* 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_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);

}