/* sdlsound.c: SDL sound I/O
   Copyright (c) 2002-2004 Alexander Yurchenko, Russell Marks, Philip Kendall,
			   Fredrick Meunier

   $Id: sdlsound.c,v 1.18.2.1 2007/02/10 00:59:36 fredm Exp $

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

*/

#include <config.h>

#include "lowlevel.h"

#ifdef SOUND_SDL

#include <errno.h>
#include <fcntl.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/time.h>

#include <SDL.h>

#include "settings.h"
#include "sfifo.h"
#include "sound.h"
#include "ui/ui.h"

static void sdlwrite( void *userdata, Uint8 *stream, int len );

sfifo_t sound_fifo;

/* Number of Spectrum frames audio latency to use */
#define NUM_FRAMES 2

/* Records sound writer status information */
static int audio_output_started;

/*
 * log2() seems to be a Linuxism, define it here as it is absent in libm
 */
double
log2(double x)
{
	return log(x)/log(2);
}

int
sound_lowlevel_init( const char *device, int *freqptr, int *stereoptr )
{
  SDL_AudioSpec requested, received;
  int error;
  float hz;
  int sound_framesiz;

  /* I'd rather just use setenv, but Windows doesn't have it */
  if( device ) {
    const char *environment = "SDL_AUDIODRIVER=";
    char *command = malloc( strlen( environment ) + strlen( device ) + 1 );
    strcpy( command, environment );
    strcat( command, device );
    error = putenv( command );
    free( command );
    if( error ) { 
      settings_current.sound = 0;
      ui_error( UI_ERROR_ERROR, "Couldn't set SDL_AUDIODRIVER: %s",
                strerror ( error ) );
      return 1;
    }
  }

  SDL_InitSubSystem( SDL_INIT_AUDIO );

  memset( &requested, 0, sizeof( SDL_AudioSpec ) );

  requested.freq = *freqptr;
  requested.channels = *stereoptr ? 2 : 1;
  requested.format = AUDIO_S16SYS;
  requested.callback = sdlwrite;

  hz = (float)machine_current->timings.processor_speed /
              machine_current->timings.tstates_per_frame;
  sound_framesiz = *freqptr / hz;
  requested.samples = pow(2.0, floor(log2(sound_framesiz)));

  if ( SDL_OpenAudio( &requested, &received ) < 0 ) {
    settings_current.sound = 0;
    ui_error( UI_ERROR_ERROR, "Couldn't open sound device: %s",
              SDL_GetError() );
    return 1;
  }

  *freqptr = received.freq;

  if( received.format != AUDIO_S16SYS ) {
    /* close audio and then just let SDL convert to this wacky format at a
       supported sample rate */
    SDL_CloseAudio();

    requested.freq = *freqptr;

    hz = (float)machine_current->timings.processor_speed /
                machine_current->timings.tstates_per_frame;
    sound_framesiz = *freqptr / hz;
    requested.samples = pow(2.0, floor(log2(sound_framesiz)));

    if( SDL_OpenAudio( &requested, NULL ) < 0 ) {
      settings_current.sound = 0;
      ui_error( UI_ERROR_ERROR, "Couldn't open sound device: %s",
                SDL_GetError() );
      return 1;
    }
  } else {
    *stereoptr = received.channels == 1 ? 0 : 1;
  }

  hz = (float)machine_current->timings.processor_speed /
              machine_current->timings.tstates_per_frame;
  sound_framesiz = *freqptr / hz;
  sound_framesiz <<= 1;

  if( ( error = sfifo_init( &sound_fifo, NUM_FRAMES
                                         * received.channels
                                         * sound_framesiz + 1 ) ) ) {
    ui_error( UI_ERROR_ERROR, "Problem initialising sound fifo: %s",
              strerror ( error ) );
    return 1;
  }

  /* wait to run sound until we have some sound to play */
  audio_output_started = 0;

  return 0;
}

void
sound_lowlevel_end( void )
{
  SDL_PauseAudio( 1 );
  SDL_LockAudio();
  SDL_CloseAudio();
  SDL_QuitSubSystem( SDL_INIT_AUDIO );
  sfifo_flush( &sound_fifo );
  sfifo_close( &sound_fifo );
}

/* Copy data to fifo */
void
sound_lowlevel_frame( libspectrum_signed_word *data, int len )
{
  int i = 0;

  /* Convert to bytes */
  libspectrum_signed_byte* bytes = (libspectrum_signed_byte*)data;
  len <<= 1;

  while( len ) {
    if( ( i = sfifo_write( &sound_fifo, bytes, len ) ) < 0 ) {
      break;
    } else if (!i) {
      SDL_Delay(10);
    }
    bytes += i;
    len -= i;
  }
  if( i < 0 ) {
    ui_error( UI_ERROR_ERROR, "Couldn't write sound fifo: %s\n",
              strerror( i ) );
  }

  if( !audio_output_started ) {
    SDL_PauseAudio( 0 );
    audio_output_started = 1;
  }
}

/* Write len samples from fifo into stream */
void
sdlwrite( void *userdata, Uint8 *stream, int len )
{
  int f;

  /* Read input_size bytes from fifo into sound stream */
  while( ( f = sfifo_read( &sound_fifo, stream, len ) ) > 0 ) {
    stream += f;
    len -= f;
  }

  /* If we ran out of sound, make do with silence :( */
  if( f < 0 ) {
    for( f=0; f<len; f++ ) {
      *stream++ = 0;
    }
    return;
  }
}

#endif			/* #ifdef SOUND_SDL */