/*

    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

*/

/* 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>

#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

#ifndef MAP_FAILED

#define MAP_FAILED	((Uint8 *)-1)

#endif

#include "SDL_audio.h"

#include "SDL_audiomem.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;

	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:

				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);

}