/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002  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@libsdl.org

*/

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <unistd.h>

#include <fcntl.h>

#include <signal.h>

#include <sys/types.h>

#include <sys/time.h>

#include <sched.h>

#include <sys/asoundlib.h>

#include <sys/select.h>

#include "SDL_audio.h"

#include "SDL_error.h"

#include "SDL_audiomem.h"

#include "SDL_audio_c.h"

#include "SDL_timer.h"

#include "SDL_nto_audio.h"

/* The tag name used by NTO audio */

#define DRIVER_NAME         "nto"

/* default channel communication parameters */

#define DEFAULT_CPARAMS_RATE 22050

#define DEFAULT_CPARAMS_VOICES 1

#define DEFAULT_CPARAMS_FRAG_SIZE 4096

#define DEFAULT_CPARAMS_FRAGS_MIN 1

#define DEFAULT_CPARAMS_FRAGS_MAX 1

/* Open the audio device for playback, and don't block if busy */

#define OPEN_FLAGS SND_PCM_OPEN_PLAYBACK

/* Audio driver functions */

static int NTO_OpenAudio(_THIS, SDL_AudioSpec *spec);

static void NTO_WaitAudio(_THIS);

static void NTO_PlayAudio(_THIS);

static Uint8 *NTO_GetAudioBuf(_THIS);

static void NTO_CloseAudio(_THIS);

static snd_pcm_channel_status_t cstatus;

static snd_pcm_channel_params_t cparams;

static snd_pcm_channel_setup_t  csetup;

/* PCM transfer channel parameters initialize function */

static void init_pcm_cparams(snd_pcm_channel_params_t* cparams)

{

	memset(cparams,0,sizeof(snd_pcm_channel_params_t));

	cparams->channel = SND_PCM_CHANNEL_PLAYBACK;

	cparams->mode = SND_PCM_MODE_BLOCK;

	cparams->start_mode = SND_PCM_START_DATA;

	cparams->stop_mode  = SND_PCM_STOP_STOP;

	cparams->format.format = SND_PCM_SFMT_S16_LE;

	cparams->format.interleave = 1;

	cparams->format.rate = DEFAULT_CPARAMS_RATE;

	cparams->format.voices = DEFAULT_CPARAMS_VOICES;

	cparams->buf.block.frag_size = DEFAULT_CPARAMS_FRAG_SIZE;

	cparams->buf.block.frags_min = DEFAULT_CPARAMS_FRAGS_MIN;

	cparams->buf.block.frags_max = DEFAULT_CPARAMS_FRAGS_MAX;

}

static int Audio_Available(void)

{

	/*

		See if we can open a nonblocking channel.

		Return value '1' means we can.

		Return value '0' means we cannot.

	*/

	int available;

	int rval;

	snd_pcm_t *handle;

	available = 0;

	handle = NULL;

	rval = snd_pcm_open_preferred(&handle, NULL, NULL, OPEN_FLAGS);

	if (rval >= 0){

		available = 1;

		if ((rval = snd_pcm_close(handle)) < 0){

			SDL_SetError("snd_pcm_close failed: %s\n",snd_strerror(rval));

			available = 0;

		}

	}

	else{

		SDL_SetError("snd_pcm_open failed: %s\n", snd_strerror(rval));

	}

	#ifdef DEBUG_AUDIO

	fprintf(stderr,"AudioAvailable rtns %d\n", available);

	#endif

	return(available);

}

static void Audio_DeleteDevice(SDL_AudioDevice *device)

{

	#ifdef DEBUG_AUDIO

	fprintf(stderr,"Audio_DeleteDevice\n");

	#endif

	free(device->hidden);

	free(device);

}

static SDL_AudioDevice *Audio_CreateDevice(int devindex)

{

	SDL_AudioDevice *this;

	#ifdef DEBUG_AUDIO

	fprintf(stderr,"Audio_CreateDevice\n");

	#endif

	/* 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_handle = NULL;

	/* Set the function pointers */

	this->OpenAudio = NTO_OpenAudio;

	this->WaitAudio = NTO_WaitAudio;

	this->PlayAudio = NTO_PlayAudio;

	this->GetAudioBuf = NTO_GetAudioBuf;

	this->CloseAudio = NTO_CloseAudio;

	this->free = Audio_DeleteDevice;

	return this;

}

	Audio_Available, Audio_CreateDevice

};

/* This function waits until it is possible to write a full sound buffer */

static void NTO_WaitAudio(_THIS)

{

	fd_set wfds;

	FD_SET( audio_fd, &wfds );

	switch( select( audio_fd + 1, NULL, &wfds, NULL, NULL ) )

	{

		case -1:

		case 0:

			/* Error */

			SDL_SetError("select() in NTO_WaitAudio failed: %s\n", strerror(errno));

			break;

		default:

			if(FD_ISSET(audio_fd, &wfds))

				return;

	}

}

static void NTO_PlayAudio(_THIS)

{

	int written, rval;

	int towrite;

	#ifdef DEBUG_AUDIO

	fprintf(stderr, "NTO_PlayAudio\n");

	#endif

	if( !this->enabled){

		return;

	}

	towrite = pcm_len;

	/* Write the audio data, checking for EAGAIN (buffer full) and underrun */

	do {

		written = snd_pcm_plugin_write(audio_handle, pcm_buf, towrite);

		#ifdef DEBUG_AUDIO

		fprintf(stderr, "NTO_PlayAudio: written = %d towrite = %d\n",written,towrite);

		#endif

		if (written != towrite){

			if ((errno == EAGAIN) || (errno == EWOULDBLOCK)){

				SDL_Delay(1);   /* Let a little CPU time go by and try to write again */

				#ifdef DEBUG_AUDIO

				fprintf(stderr, "errno == EAGAIN written %d\n", written);

				#endif

				towrite -= written; //we wrote some data

				continue;

			}		

			else if((errno == EINVAL) || (errno == EIO)){

				if(errno == EIO){

					#ifdef DEBUG_AUDIO

					fprintf(stderr,"snd_pcm_plugin_write failed EIO: %s\n", snd_strerror(written));

					#endif

				}

				if(errno == EINVAL){

					#ifdef DEBUG_AUDIO

					fprintf(stderr,"snd_pcm_plugin_write failed EINVAL: %s\n", snd_strerror(written));	

					#endif

				}

				memset(&cstatus, 0, sizeof(cstatus));

				if( (rval = snd_pcm_plugin_status(audio_handle, &cstatus)) < 0 ){

					#ifdef DEBUG_AUDIO

					fprintf(stderr, "snd_pcm_plugin_status failed %s\n",snd_strerror(rval));

					#endif

					SDL_SetError("snd_pcm_plugin_status failed: %s\n", snd_strerror(rval));

					return;

				}	

				if ( (cstatus.status == SND_PCM_STATUS_UNDERRUN) || (cstatus.status == SND_PCM_STATUS_READY) ){

					#ifdef DEBUG_AUDIO

					fprintf(stderr, "buffer underrun\n");

					#endif

					if ( (rval = snd_pcm_plugin_prepare (audio_handle,SND_PCM_CHANNEL_PLAYBACK)) < 0 ){

						#ifdef DEBUG_AUDIO

						fprintf(stderr, "NTO_PlayAudio: prepare failed %s\n",snd_strerror(rval));

						#endif

						SDL_SetError("snd_pcm_plugin_prepare failed: %s\n",snd_strerror(rval) );

						return;

					}

				}		        		

 				continue;

			}

			else{

				#ifdef DEBUG_AUDIO

				fprintf(stderr, "NTO_PlayAudio: snd_pcm_plugin_write failed unknown errno %d %s\n",errno, snd_strerror(rval));

				#endif

				return;

			}

		}

		else

		{

			towrite -= written; //we wrote all remaining data

		}

	} while ( (towrite > 0)  && (this->enabled) );

	/* If we couldn't write, assume fatal error for now */

	if ( towrite != 0 ) {

		this->enabled = 0;

	}

	return;

}

static Uint8 *NTO_GetAudioBuf(_THIS)

{

	#ifdef DEBUG_AUDIO

	fprintf(stderr, "NTO_GetAudioBuf: pcm_buf %X\n",(Uint8 *)pcm_buf);

	#endif

	return(pcm_buf);

}

static void NTO_CloseAudio(_THIS)

{

	int rval;

	#ifdef DEBUG_AUDIO

	fprintf(stderr, "NTO_CloseAudio\n");

	#endif

	this->enabled = 0;

	if ( audio_handle != NULL ) {

		if ((rval = snd_pcm_plugin_flush(audio_handle,SND_PCM_CHANNEL_PLAYBACK)) < 0){

			SDL_SetError("snd_pcm_plugin_flush failed: %s\n",snd_strerror(rval));

			return;

		}

		if ((rval = snd_pcm_close(audio_handle)) < 0){

			SDL_SetError("snd_pcm_close failed: %s\n",snd_strerror(rval));

			return;

		}

		audio_handle = NULL;

	}

}

static int NTO_OpenAudio(_THIS, SDL_AudioSpec *spec)

{

	int rval;

	int format;

	Uint16 test_format;

	int twidth;

	int found;

	#ifdef DEBUG_AUDIO

	fprintf(stderr, "NTO_OpenAudio\n");

	#endif

	audio_handle = NULL;

	this->enabled = 0;

	if ( pcm_buf != NULL ) {

		free((Uint8 *)pcm_buf); 

		pcm_buf = NULL;

	}

	/* initialize channel transfer parameters to default */

	init_pcm_cparams(&cparams);

	/* Open the audio device */

	rval = snd_pcm_open_preferred(&audio_handle, NULL, NULL, OPEN_FLAGS);

	if ( rval < 0 ) {

		SDL_SetError("snd_pcm_open failed: %s\n", snd_strerror(rval));

		return(-1);

	}

	/* enable count status parameter */

	if ((rval = snd_pcm_plugin_set_disable(audio_handle, PLUGIN_DISABLE_MMAP))<0){

		SDL_SetError("snd_pcm_plugin_set_disable failed: %s\n", snd_strerror(rval));

		return(-1);

	}

	/* Try for a closest match on audio format */

	format = 0;

 	found = 0; /* can't use format as SND_PCM_SFMT_U8 = 0 in nto */

	for ( test_format = SDL_FirstAudioFormat(spec->format);	!found ; ) 

	{

		#ifdef DEBUG_AUDIO

		fprintf(stderr, "Trying format 0x%4.4x spec->samples %d\n", test_format,spec->samples);

		#endif

		/* if match found set format to equivalent ALSA format */

		switch ( test_format ) {

			case AUDIO_U8:

				format = SND_PCM_SFMT_U8;

				found = 1;

				break;

			case AUDIO_S8:

				format = SND_PCM_SFMT_S8;

				found = 1;

				break;

			case AUDIO_S16LSB:

				format = SND_PCM_SFMT_S16_LE;

				found = 1;

				break;

			case AUDIO_S16MSB:

				format = SND_PCM_SFMT_S16_BE;

				found = 1;

				break;

			case AUDIO_U16LSB:

				format = SND_PCM_SFMT_U16_LE;

				found = 1;

				break;

			case AUDIO_U16MSB:

				format = SND_PCM_SFMT_U16_BE;

				found = 1;

				break;

			default:

				break;

		}

		if ( ! found ) {

			test_format = SDL_NextAudioFormat();

		}

	}

	/* assumes test_format not 0 on success */

	if ( test_format == 0 ) {

		SDL_SetError("Couldn't find any hardware audio formats");

		return(-1);

	}

	spec->format = test_format;

	/* Set the audio format */

	cparams.format.format = format;

	/* Set mono or stereo audio (currently only two channels supported) */

	cparams.format.voices = spec->channels;

	#ifdef DEBUG_AUDIO

	fprintf(stderr,"intializing channels %d\n", cparams.format.voices);

	#endif

	/* Set rate */

	cparams.format.rate = spec->freq ;

	/* Setup the transfer parameters according to cparams */

	rval = snd_pcm_plugin_params(audio_handle, &cparams);

	if (rval < 0) {

		SDL_SetError("snd_pcm_channel_params failed: %s\n", snd_strerror (rval));

		return(-1);

	}

	/*  Make sure channel is setup right one last time */

	memset( &csetup, 0, sizeof( csetup ) );

	csetup.channel = SND_PCM_CHANNEL_PLAYBACK;

	if ( snd_pcm_plugin_setup( audio_handle, &csetup ) < 0 )

	{

		SDL_SetError("Unable to setup playback channel\n" );

		return(-1);

	}

	else

	{

		#ifdef DEBUG_AUDIO

		fprintf(stderr,"requested format: %d\n",cparams.format.format);

		fprintf(stderr,"requested frag size: %d\n",cparams.buf.block.frag_size);

		fprintf(stderr,"requested max frags: %d\n\n",cparams.buf.block.frags_max);

		fprintf(stderr,"real format: %d\n", csetup.format.format );

		fprintf(stderr,"real frag size : %d\n", csetup.buf.block.frag_size );

		fprintf(stderr,"real max frags : %d\n", csetup.buf.block.frags_max );

		#endif

	}

	/*

		Allocate memory to the audio buffer and initialize with silence (Note that

		buffer size must be a multiple of fragment size, so find closest multiple)

	*/

	twidth = snd_pcm_format_width(format);

	if (twidth < 0) {

		printf("snd_pcm_format_width failed\n");

		twidth = 0;

	}

	#ifdef DEBUG_AUDIO

	fprintf(stderr,"format is %d bits wide\n",twidth);

	#endif

	pcm_len = spec->size ;

	#ifdef DEBUG_AUDIO

	fprintf(stderr,"pcm_len set to %d\n", pcm_len);

	#endif

	if (pcm_len == 0){

		pcm_len = csetup.buf.block.frag_size;

	}

	pcm_buf = (Uint8*)malloc(pcm_len);

	if (pcm_buf == NULL) {

		SDL_SetError("pcm_buf malloc failed\n");

		return(-1);

	}

	memset(pcm_buf,spec->silence,pcm_len);

	#ifdef DEBUG_AUDIO

	fprintf(stderr,"pcm_buf malloced and silenced.\n");

	#endif

	/* get the file descriptor */

	if( (audio_fd = snd_pcm_file_descriptor(audio_handle, SND_PCM_CHANNEL_PLAYBACK)) < 0){

		fprintf(stderr, "snd_pcm_file_descriptor failed with error code: %d\n", audio_fd);

	}

	/* Trigger audio playback */

	rval = snd_pcm_plugin_prepare( audio_handle, SND_PCM_CHANNEL_PLAYBACK);

	if (rval < 0) {

		SDL_SetError("snd_pcm_plugin_prepare failed: %s\n", snd_strerror (rval));

		return(-1);

	}

	this->enabled = 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);

}