// Game_Music_Emu https://bitbucket.org/mpyne/game-music-emu/

#include "Dual_Resampler.h"

#include <stdlib.h>

#include <string.h>

/* Copyright (C) 2003-2006 Shay Green. This module 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

module 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 module; if not, write to the Free Software Foundation,

Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */

#include "blargg_source.h"

Dual_Resampler::Dual_Resampler() :

  sample_buf_size(0),

  oversamples_per_frame(-1),

  buf_pos(-1),

  resampler_size(0)

{

}

Dual_Resampler::~Dual_Resampler() { }

blargg_err_t Dual_Resampler::reset( int pairs )

{

  // expand allocations a bit

  RETURN_ERR( sample_buf.resize( (pairs + (pairs >> 2)) * 2 ) );

  resize( pairs );

  resampler_size = oversamples_per_frame + (oversamples_per_frame >> 2);

  return resampler.buffer_size( resampler_size );

}

void Dual_Resampler::resize( int pairs )

{

  int new_sample_buf_size = pairs * 2;

  if ( sample_buf_size != new_sample_buf_size )

  {

    if ( (unsigned) new_sample_buf_size > sample_buf.size() )

    {

      check( false );

      return;

    }

    sample_buf_size = new_sample_buf_size;

    oversamples_per_frame = int (pairs * resampler.ratio()) * 2 + 2;

    clear();

  }

}

void Dual_Resampler::play_frame_( Blip_Buffer& blip_buf, dsample_t* out )

{

  long pair_count = sample_buf_size >> 1;

  blip_time_t blip_time = blip_buf.count_clocks( pair_count );

  int sample_count = oversamples_per_frame - resampler.written();

  int new_count = play_frame( blip_time, sample_count, resampler.buffer() );

  assert( new_count < resampler_size );

  blip_buf.end_frame( blip_time );

  assert( blip_buf.samples_avail() == pair_count );

  resampler.write( new_count );

#ifdef  NDEBUG // Avoid warning when asserts are disabled

  resampler.read( sample_buf.begin(), sample_buf_size );

#else

  long count = resampler.read( sample_buf.begin(), sample_buf_size );

  assert( count == (long) sample_buf_size );

#endif

  mix_samples( blip_buf, out );

  blip_buf.remove_samples( pair_count );

}

void Dual_Resampler::dual_play( long count, dsample_t* out, Blip_Buffer& blip_buf )

{

  // empty extra buffer

  long remain = sample_buf_size - buf_pos;

  if ( remain )

  {

    if ( remain > count )

      remain = count;

    count -= remain;

    memcpy( out, &sample_buf [buf_pos], remain * sizeof *out );

    out += remain;

    buf_pos += remain;

  }

  // entire frames

  while ( count >= (long) sample_buf_size )

  {

    play_frame_( blip_buf, out );

    out += sample_buf_size;

    count -= sample_buf_size;

  }

  // extra

  if ( count )

  {

    play_frame_( blip_buf, sample_buf.begin() );

    buf_pos = count;

    memcpy( out, sample_buf.begin(), count * sizeof *out );

    out += count;

  }

}

void Dual_Resampler::mix_samples( Blip_Buffer& blip_buf, dsample_t* out )

{

  Blip_Reader sn;

  int bass = sn.begin( blip_buf );

  const dsample_t* in = sample_buf.begin();

  for ( int n = sample_buf_size >> 1; n--; )

  {

    int s = sn.read();

    int32_t l = (int32_t) in [0] * 2 + s;

    if ( (int16_t) l != l )

      l = 0x7FFF - (l >> 24);

    sn.next( bass );

    int32_t r = (int32_t) in [1] * 2 + s;

    if ( (int16_t) r != r )

      r = 0x7FFF - (r >> 24);

    in += 2;

    out [0] = l;

    out [1] = r;

    out += 2;

  }

  sn.end( blip_buf );

}