// Blip_Buffer 0.4.1. http://www.slack.net/~ant/

 

 #include "Blip_Buffer.h"

 

 #include <assert.h>

 #include <limits.h>

 #include <string.h>

 #include <stdlib.h>

 #include <math.h>

 

 /* Copyright (C) 2003-2007 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 */

 

 // TODO: use scoped for variables in treble_eq()

 

 #ifdef BLARGG_ENABLE_OPTIMIZER

 #include BLARGG_ENABLE_OPTIMIZER

 #endif

 

 int const silent_buf_size = 1; // size used for Silent_Blip_Buffer

 

 Blip_Buffer::Blip_Buffer()

 {

   factor_       = LONG_MAX;

   buffer_       = 0;

   buffer_size_  = 0;

   sample_rate_  = 0;

   bass_shift_   = 0;

   clock_rate_   = 0;

   bass_freq_    = 16;

   length_       = 0;

 

   // assumptions code makes about implementation-defined features

 #ifndef NDEBUG

   // right shift of negative value preserves sign

   buf_t_ i = -0x7FFFFFFE;

   assert( (i >> 1) == -0x3FFFFFFF );

 

   // casting to short truncates to 16 bits and sign-extends

   i = 0x18000;

   assert( (short) i == -0x8000 );

 #endif

 

   Clear();

 }

 

 Blip_Buffer::~Blip_Buffer()

 {

   if ( buffer_size_ != silent_buf_size )

     free( buffer_ );

 }

 

 Silent_Blip_Buffer::Silent_Blip_Buffer()

 {

   factor_      = 0;

   buffer_      = buf;

   buffer_size_ = silent_buf_size;

   clear();

 }

 

 void Blip_Buffer::clear( int entire_buffer )

 {

   offset_       = 0;

   reader_accum_ = 0;

   modified_     = 0;

   if ( buffer_ )

     {

       long count = (entire_buffer ? buffer_size_ : samples_avail());

       memset( buffer_, 0, (count + blip_buffer_extra_) * sizeof (buf_t_) );

     }

 }

 

 Blip_Buffer::blargg_err_t Blip_Buffer::set_sample_rate( long new_rate, int msec )

 {

   if ( buffer_size_ == silent_buf_size )

     {

       assert( 0 );

       return "Internal (tried to resize Silent_Blip_Buffer)";

     }

 

   // start with maximum length that resampled time can represent

   long new_size = (ULONG_MAX >> BLIP_BUFFER_ACCURACY) - blip_buffer_extra_ - 64;

   if ( msec != blip_max_length )

     {

       long s = (new_rate * (msec + 1) + 999) / 1000;

       if ( s < new_size )

 	new_size = s;

       else

 	assert( 0 ); // fails if requested buffer length exceeds limit

     }

 

   if ( buffer_size_ != new_size )

     {

       void* p = realloc( buffer_, (new_size + blip_buffer_extra_) * sizeof *buffer_ );

       if ( !p )

 	return "Out of memory";

       buffer_ = (buf_t_*) p;

     }

 

   buffer_size_ = new_size;

   assert( buffer_size_ != silent_buf_size ); // size should never happen to match this

 

   // update things based on the sample rate

   sample_rate_ = new_rate;

   length_ = new_size * 1000 / new_rate - 1;

   if ( msec )

     assert( length_ == msec ); // ensure length is same as that passed in

 

   // update these since they depend on sample rate

   if ( clock_rate_ )

     clock_rate( clock_rate_ );

   bass_freq( bass_freq_ );

 

   clear();

 

   return 0; // success

 }

 

 blip_resampled_time_t Blip_Buffer::clock_rate_factor( long rate ) const

 {

   double ratio = (double) sample_rate_ / rate;

   blip_long factor = (blip_long) floor( ratio * (1L << BLIP_BUFFER_ACCURACY) + 0.5 );

   assert( factor > 0 || !sample_rate_ ); // fails if clock/output ratio is too large

   return (blip_resampled_time_t) factor;

 }

 

 void Blip_Buffer::bass_freq( int freq )

 {

   bass_freq_ = freq;

   int shift = 31;

   if ( freq > 0 )

     {

       shift = 13;

       long f = (freq << 16) / sample_rate_;

       while ( (f >>= 1) && --shift ) { }

     }

   bass_shift_ = shift;

 }

 

 void Blip_Buffer::end_frame( blip_time_t t )

 {

   offset_ += t * factor_;

   assert( samples_avail() <= (long) buffer_size_ ); // fails if time is past end of buffer

 }

 

 long Blip_Buffer::count_samples( blip_time_t t ) const

 {

   blip_resampled_time_t last_sample  = resampled_time( t ) >> BLIP_BUFFER_ACCURACY;

   blip_resampled_time_t first_sample = offset_ >> BLIP_BUFFER_ACCURACY;

   return long (last_sample - first_sample);

 }

 

 blip_time_t Blip_Buffer::count_clocks( long count ) const

 {

   if ( !factor_ )

     {

       assert( 0 ); // sample rate and clock rates must be set first

       return 0;

     }

 

   if ( count > buffer_size_ )

     count = buffer_size_;

   blip_resampled_time_t time = (blip_resampled_time_t) count << BLIP_BUFFER_ACCURACY;

   return (blip_time_t) ((time - offset_ + factor_ - 1) / factor_);

 }

 

 void Blip_Buffer::remove_samples( long count )

 {

   if ( count )

     {

       remove_silence( count );

 

       // copy remaining samples to beginning and clear old samples

       long remain = samples_avail() + blip_buffer_extra_;

       memmove( buffer_, buffer_ + count, remain * sizeof *buffer_ );

       memset( buffer_ + remain, 0, count * sizeof *buffer_ );

     }

 }

 

 // Blip_Synth_

 

 Blip_Synth_Fast_::Blip_Synth_Fast_()

 {

   buf          = 0;

   last_amp     = 0;

   delta_factor = 0;

 }

 

 void Blip_Synth_Fast_::volume_unit( double new_unit )

 {

   delta_factor = int (new_unit * (1L << blip_sample_bits) + 0.5);

 }

 

 #if !BLIP_BUFFER_FAST

 

 Blip_Synth_::Blip_Synth_( short* p, int w ) :

   impulses( p ),

   width( w )

 {

   volume_unit_ = 0.0;

   kernel_unit  = 0;

   buf          = 0;

   last_amp     = 0;

   delta_factor = 0;

 }

 

 #undef PI

 #define PI 3.1415926535897932384626433832795029

 

 static void gen_sinc( float* out, int count, double oversample, double treble, double cutoff )

 {

   if ( cutoff >= 0.999 )

     cutoff = 0.999;

 

   if ( treble < -300.0 )

     treble = -300.0;

   if ( treble > 5.0 )

     treble = 5.0;

 

   double const maxh = 4096.0;

   double const rolloff = pow( 10.0, 1.0 / (maxh * 20.0) * treble / (1.0 - cutoff) );

   double const pow_a_n = pow( rolloff, maxh - maxh * cutoff );

   double const to_angle = PI / 2 / maxh / oversample;

   for ( int i = 0; i < count; i++ )

     {

       double angle = ((i - count) * 2 + 1) * to_angle;

       double c = rolloff * cos( (maxh - 1.0) * angle ) - cos( maxh * angle );

       double cos_nc_angle = cos( maxh * cutoff * angle );

       double cos_nc1_angle = cos( (maxh * cutoff - 1.0) * angle );

       double cos_angle = cos( angle );

 

       c = c * pow_a_n - rolloff * cos_nc1_angle + cos_nc_angle;

       double d = 1.0 + rolloff * (rolloff - cos_angle - cos_angle);

       double b = 2.0 - cos_angle - cos_angle;

       double a = 1.0 - cos_angle - cos_nc_angle + cos_nc1_angle;

 

       out [i] = (float) ((a * d + c * b) / (b * d)); // a / b + c / d

     }

 }

 

 void blip_eq_t::generate( float* out, int count ) const

 {

   // lower cutoff freq for narrow kernels with their wider transition band

   // (8 points->1.49, 16 points->1.15)

   double oversample = blip_res * 2.25 / count + 0.85;

   double half_rate = sample_rate * 0.5;

   if ( cutoff_freq )

     oversample = half_rate / cutoff_freq;

   double cutoff = rolloff_freq * oversample / half_rate;

 

   gen_sinc( out, count, blip_res * oversample, treble, cutoff );

 

   // apply (half of) hamming window

   double to_fraction = PI / (count - 1);

   for ( int i = count; i--; )

     out [i] *= 0.54f - 0.46f * (float) cos( i * to_fraction );

 }

 

 void Blip_Synth_::adjust_impulse()

 {

   // sum pairs for each phase and add error correction to end of first half

   int const size = impulses_size();

   for ( int p = blip_res; p-- >= blip_res / 2; )

     {

       int p2 = blip_res - 2 - p;

       long error = kernel_unit;

       for ( int i = 1; i < size; i += blip_res )

 	{

 	  error -= impulses [i + p ];

 	  error -= impulses [i + p2];

 	}

       if ( p == p2 )

 	error /= 2; // phase = 0.5 impulse uses same half for both sides

       impulses [size - blip_res + p] += (short) error;

       //printf( "error: %ld\n", error );

     }

 

   //for ( int i = blip_res; i--; printf( "\n" ) )

   //  for ( int j = 0; j < width / 2; j++ )

   //      printf( "%5ld,", impulses [j * blip_res + i + 1] );

 }

 

 void Blip_Synth_::treble_eq( blip_eq_t const& eq )

 {

   float fimpulse [blip_res / 2 * (blip_widest_impulse_ - 1) + blip_res * 2];

 

   int const half_size = blip_res / 2 * (width - 1);

   eq.generate( &fimpulse [blip_res], half_size );

 

   int i;

 

   // need mirror slightly past center for calculation

   for ( i = blip_res; i--; )

     fimpulse [blip_res + half_size + i] = fimpulse [blip_res + half_size - 1 - i];

 

   // starts at 0

   for ( i = 0; i < blip_res; i++ )

     fimpulse [i] = 0.0f;

 

   // find rescale factor

   double total = 0.0;

   for ( i = 0; i < half_size; i++ )

     total += fimpulse [blip_res + i];

 

   //double const base_unit = 44800.0 - 128 * 18; // allows treble up to +0 dB

   //double const base_unit = 37888.0; // allows treble to +5 dB

   double const base_unit = 32768.0; // necessary for blip_unscaled to work

   double rescale = base_unit / 2 / total;

   kernel_unit = (long) base_unit;

 

   // integrate, first difference, rescale, convert to int

   double sum = 0.0;

   double next = 0.0;

   int const size = this->impulses_size();

   for ( i = 0; i < size; i++ )

     {

       impulses [i] = (short) (int) floor( (next - sum) * rescale + 0.5 );

       sum += fimpulse [i];

       next += fimpulse [i + blip_res];

     }

   adjust_impulse();

 

   // volume might require rescaling

   double vol = volume_unit_;

   if ( vol )

     {

       volume_unit_ = 0.0;

       volume_unit( vol );

     }

 }

 

 void Blip_Synth_::volume_unit( double new_unit )

 {

   if ( new_unit != volume_unit_ )

     {

       // use default eq if it hasn't been set yet

       if ( !kernel_unit )

 	treble_eq( -8.0 );

 

       volume_unit_ = new_unit;

       double factor = new_unit * (1L << blip_sample_bits) / kernel_unit;

 

       if ( factor > 0.0 )

 	{

 	  int shift = 0;

 

 	  // if unit is really small, might need to attenuate kernel

 	  while ( factor < 2.0 )

 	    {

 	      shift++;

 	      factor *= 2.0;

 	    }

 

 	  if ( shift )

 	    {

 	      kernel_unit >>= shift;

 	      assert( kernel_unit > 0 ); // fails if volume unit is too low

 

 	      // keep values positive to avoid round-towards-zero of sign-preserving

 	      // right shift for negative values

 	      long offset = 0x8000 + (1 << (shift - 1));

 	      long offset2 = 0x8000 >> shift;

 	      for ( int i = impulses_size(); i--; )

 		impulses [i] = (short) (int) (((impulses [i] + offset) >> shift) - offset2);

 	      adjust_impulse();

 	    }

 	}

       delta_factor = (int) floor( factor + 0.5 );

       //printf( "delta_factor: %d, kernel_unit: %d\n", delta_factor, kernel_unit );

     }

 }

 #endif

 

 long Blip_Buffer::read_samples( blip_sample_t* out_, long max_samples, int stereo )

 {

   long count = samples_avail();

   if ( count > max_samples )

     count = max_samples;

 

   if ( count )

     {

       int const bass = BLIP_READER_BASS( *this );

       BLIP_READER_BEGIN( reader, *this );

       BLIP_READER_ADJ_( reader, count );

       blip_sample_t* BLIP_RESTRICT out = out_ + count;

       blip_long offset = (blip_long) -count;

 

       if ( !stereo )

 	{

 	  do

 	    {

 	      blip_long s = BLIP_READER_READ( reader );

 	      BLIP_READER_NEXT_IDX_( reader, bass, offset );

 	      BLIP_CLAMP( s, s );

 	      out [offset] = (blip_sample_t) s;

 	    }

 	  while ( ++offset );

 	}

       else

 	{

 	  do

 	    {

 	      blip_long s = BLIP_READER_READ( reader );

 	      BLIP_READER_NEXT_IDX_( reader, bass, offset );

 	      BLIP_CLAMP( s, s );

 	      out [offset * 2] = (blip_sample_t) s;

 	    }

 	  while ( ++offset );

 	}

 

       BLIP_READER_END( reader, *this );

 

       remove_samples( count );

     }

   return count;

 }

 

 void Blip_Buffer::mix_samples( blip_sample_t const* in, long count )

 {

   if ( buffer_size_ == silent_buf_size )

     {

       assert( 0 );

       return;

     }

 

   buf_t_* out = buffer_ + (offset_ >> BLIP_BUFFER_ACCURACY) + blip_widest_impulse_ / 2;

 

   int const sample_shift = blip_sample_bits - 16;

   int prev = 0;

   while ( count-- )

     {

       blip_long s = (blip_long) *in++ << sample_shift;

       *out += s - prev;

       prev = s;

       ++out;

     }

   *out -= prev;

 }

 

 blip_ulong const subsample_mask = (1L << BLIP_BUFFER_ACCURACY) - 1;

 

 void Blip_Buffer::save_state( blip_buffer_state_t* out )

 {

   assert( samples_avail() == 0 );

   out->offset_       = offset_;

   out->reader_accum_ = reader_accum_;

   memcpy( out->buf, &buffer_ [offset_ >> BLIP_BUFFER_ACCURACY], sizeof out->buf );

 }

 

 void Blip_Buffer::load_state( blip_buffer_state_t const& in )

 {

   clear( false );

 

   offset_       = in.offset_;

   reader_accum_ = in.reader_accum_;

   memcpy( buffer_, in.buf, sizeof in.buf );

 }