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718112a8fe
Currently none of these is being used, but eventually they will, once more code gets ported over. So it's better to have them right away and avoid editing the project file too much, only to revert that later.
460 lines
12 KiB
C++
460 lines
12 KiB
C++
// Blip_Buffer 0.4.1. http://www.slack.net/~ant/
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#include "Blip_Buffer.h"
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#include <assert.h>
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#include <limits.h>
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#include <string.h>
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#include <stdlib.h>
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#include <math.h>
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/* Copyright (C) 2003-2006 Shay Green. This module is free software; you
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can redistribute it and/or modify it under the terms of the GNU Lesser
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General Public License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version. This
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module is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
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details. You should have received a copy of the GNU Lesser General Public
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License along with this module; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
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#ifdef BLARGG_ENABLE_OPTIMIZER
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#include BLARGG_ENABLE_OPTIMIZER
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#endif
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int const silent_buf_size = 1; // size used for Silent_Blip_Buffer
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Blip_Buffer::Blip_Buffer()
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{
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factor_ = (blip_ulong)-1 / 2;
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offset_ = 0;
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buffer_ = 0;
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buffer_size_ = 0;
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sample_rate_ = 0;
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reader_accum_ = 0;
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bass_shift_ = 0;
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clock_rate_ = 0;
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bass_freq_ = 16;
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length_ = 0;
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// assumptions code makes about implementation-defined features
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#ifndef NDEBUG
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// right shift of negative value preserves sign
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buf_t_ i = -0x7FFFFFFE;
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assert( (i >> 1) == -0x3FFFFFFF );
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// casting to short truncates to 16 bits and sign-extends
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i = 0x18000;
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assert( (short) i == -0x8000 );
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#endif
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}
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Blip_Buffer::~Blip_Buffer()
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{
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if ( buffer_size_ != silent_buf_size )
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free( buffer_ );
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}
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Silent_Blip_Buffer::Silent_Blip_Buffer()
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{
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factor_ = 0;
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buffer_ = buf;
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buffer_size_ = silent_buf_size;
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memset( buf, 0, sizeof buf ); // in case machine takes exception for signed overflow
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}
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void Blip_Buffer::clear( int entire_buffer )
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{
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offset_ = 0;
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reader_accum_ = 0;
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modified_ = 0;
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if ( buffer_ )
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{
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long count = (entire_buffer ? buffer_size_ : samples_avail());
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memset( buffer_, 0, (count + blip_buffer_extra_) * sizeof (buf_t_) );
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}
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}
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Blip_Buffer::blargg_err_t Blip_Buffer::set_sample_rate( long new_rate, int msec )
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{
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if ( buffer_size_ == silent_buf_size )
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{
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assert( 0 );
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return "Internal (tried to resize Silent_Blip_Buffer)";
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}
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// start with maximum length that resampled time can represent
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long new_size = (UINT_MAX >> BLIP_BUFFER_ACCURACY) - blip_buffer_extra_ - 64;
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if ( msec != blip_max_length )
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{
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long s = (new_rate * (msec + 1) + 999) / 1000;
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if ( s < new_size )
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new_size = s;
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else
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assert( 0 ); // fails if requested buffer length exceeds limit
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}
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if ( buffer_size_ != new_size )
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{
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void* p = realloc( buffer_, (new_size + blip_buffer_extra_) * sizeof *buffer_ );
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if ( !p )
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return "Out of memory";
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buffer_ = (buf_t_*) p;
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}
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buffer_size_ = new_size;
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assert( buffer_size_ != silent_buf_size );
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// update things based on the sample rate
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sample_rate_ = new_rate;
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length_ = new_size * 1000 / new_rate - 1;
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if ( msec )
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assert( length_ == msec ); // ensure length is same as that passed in
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if ( clock_rate_ )
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clock_rate( clock_rate_ );
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bass_freq( bass_freq_ );
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clear();
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return 0; // success
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}
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blip_resampled_time_t Blip_Buffer::clock_rate_factor( long rate ) const
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{
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double ratio = (double) sample_rate_ / rate;
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blip_long factor = (blip_long) floor( ratio * (1L << BLIP_BUFFER_ACCURACY) + 0.5 );
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assert( factor > 0 || !sample_rate_ ); // fails if clock/output ratio is too large
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return (blip_resampled_time_t) factor;
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}
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void Blip_Buffer::bass_freq( int freq )
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{
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bass_freq_ = freq;
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int shift = 31;
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if ( freq > 0 )
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{
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shift = 13;
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long f = (freq << 16) / sample_rate_;
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while ( (f >>= 1) && --shift ) { }
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}
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bass_shift_ = shift;
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}
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void Blip_Buffer::end_frame( blip_time_t t )
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{
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offset_ += t * factor_;
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assert( samples_avail() <= (long) buffer_size_ ); // time outside buffer length
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}
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void Blip_Buffer::remove_silence( long count )
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{
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assert( count <= samples_avail() ); // tried to remove more samples than available
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offset_ -= (blip_resampled_time_t) count << BLIP_BUFFER_ACCURACY;
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}
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long Blip_Buffer::count_samples( blip_time_t t ) const
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{
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unsigned long last_sample = resampled_time( t ) >> BLIP_BUFFER_ACCURACY;
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unsigned long first_sample = offset_ >> BLIP_BUFFER_ACCURACY;
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return (long) (last_sample - first_sample);
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}
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blip_time_t Blip_Buffer::count_clocks( long count ) const
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{
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if ( !factor_ )
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{
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assert( 0 ); // sample rate and clock rates must be set first
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return 0;
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}
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if ( count > buffer_size_ )
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count = buffer_size_;
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blip_resampled_time_t time = (blip_resampled_time_t) count << BLIP_BUFFER_ACCURACY;
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return (blip_time_t) ((time - offset_ + factor_ - 1) / factor_);
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}
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void Blip_Buffer::remove_samples( long count )
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{
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if ( count )
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{
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remove_silence( count );
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// copy remaining samples to beginning and clear old samples
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long remain = samples_avail() + blip_buffer_extra_;
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memmove( buffer_, buffer_ + count, remain * sizeof *buffer_ );
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memset( buffer_ + remain, 0, count * sizeof *buffer_ );
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}
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}
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// Blip_Synth_
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Blip_Synth_Fast_::Blip_Synth_Fast_()
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{
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buf = 0;
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last_amp = 0;
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delta_factor = 0;
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}
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void Blip_Synth_Fast_::volume_unit( double new_unit )
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{
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delta_factor = int (new_unit * (1L << blip_sample_bits) + 0.5);
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}
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#if !BLIP_BUFFER_FAST
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Blip_Synth_::Blip_Synth_( short* p, int w ) :
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impulses( p ),
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width( w )
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{
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volume_unit_ = 0.0;
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kernel_unit = 0;
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buf = 0;
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last_amp = 0;
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delta_factor = 0;
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}
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#undef PI
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#define PI 3.1415926535897932384626433832795029
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static void gen_sinc( float* out, int count, double oversample, double treble, double cutoff )
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{
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if ( cutoff >= 0.999 )
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cutoff = 0.999;
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if ( treble < -300.0 )
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treble = -300.0;
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if ( treble > 5.0 )
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treble = 5.0;
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double const maxh = 4096.0;
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double const rolloff = pow( 10.0, 1.0 / (maxh * 20.0) * treble / (1.0 - cutoff) );
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double const pow_a_n = pow( rolloff, maxh - maxh * cutoff );
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double const to_angle = PI / 2 / maxh / oversample;
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for ( int i = 0; i < count; i++ )
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{
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double angle = ((i - count) * 2 + 1) * to_angle;
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double angle_maxh = angle * maxh;
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double angle_maxh_mid = angle_maxh * cutoff;
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double y = maxh;
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// 0 to Fs/2*cutoff, flat
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if ( angle_maxh_mid ) // unstable at t=0
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y *= sin( angle_maxh_mid ) / angle_maxh_mid;
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// Fs/2*cutoff to Fs/2, logarithmic rolloff
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double cosa = cos( angle );
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double den = 1 + rolloff * (rolloff - cosa - cosa);
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// Becomes unstable when rolloff is near 1.0 and t is near 0,
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// which is the only time den becomes small
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if ( den > 1e-13 )
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{
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double num =
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(cos( angle_maxh - angle ) * rolloff - cos( angle_maxh )) * pow_a_n -
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cos( angle_maxh_mid - angle ) * rolloff + cos( angle_maxh_mid );
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y = y * cutoff + num / den;
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}
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out [i] = (float) y;
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}
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}
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void blip_eq_t::generate( float* out, int count ) const
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{
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// lower cutoff freq for narrow kernels with their wider transition band
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// (8 points->1.49, 16 points->1.15)
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double oversample = blip_res * 2.25 / count + 0.85;
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double half_rate = sample_rate * 0.5;
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if ( cutoff_freq )
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oversample = half_rate / cutoff_freq;
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double cutoff = rolloff_freq * oversample / half_rate;
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gen_sinc( out, count, blip_res * oversample, treble, cutoff );
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// apply (half of) hamming window
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double to_fraction = PI / (count - 1);
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for ( int i = count; i--; )
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out [i] *= 0.54f - 0.46f * (float) cos( i * to_fraction );
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}
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void Blip_Synth_::adjust_impulse()
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{
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// sum pairs for each phase and add error correction to end of first half
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int const size = impulses_size();
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for ( int p = blip_res; p-- >= blip_res / 2; )
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{
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int p2 = blip_res - 2 - p;
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long error = kernel_unit;
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for ( int i = 1; i < size; i += blip_res )
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{
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error -= impulses [i + p ];
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error -= impulses [i + p2];
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}
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if ( p == p2 )
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error /= 2; // phase = 0.5 impulse uses same half for both sides
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impulses [size - blip_res + p] += (short) error;
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//printf( "error: %ld\n", error );
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}
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//for ( int i = blip_res; i--; printf( "\n" ) )
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// for ( int j = 0; j < width / 2; j++ )
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// printf( "%5ld,", impulses [j * blip_res + i + 1] );
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}
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void Blip_Synth_::treble_eq( blip_eq_t const& eq )
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{
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float fimpulse [blip_res / 2 * (blip_widest_impulse_ - 1) + blip_res * 2];
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int const half_size = blip_res / 2 * (width - 1);
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eq.generate( &fimpulse [blip_res], half_size );
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int i;
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// need mirror slightly past center for calculation
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for ( i = blip_res; i--; )
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fimpulse [blip_res + half_size + i] = fimpulse [blip_res + half_size - 1 - i];
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// starts at 0
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for ( i = 0; i < blip_res; i++ )
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fimpulse [i] = 0.0f;
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// find rescale factor
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double total = 0.0;
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for ( i = 0; i < half_size; i++ )
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total += fimpulse [blip_res + i];
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//double const base_unit = 44800.0 - 128 * 18; // allows treble up to +0 dB
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//double const base_unit = 37888.0; // allows treble to +5 dB
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double const base_unit = 32768.0; // necessary for blip_unscaled to work
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double rescale = base_unit / 2 / total;
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kernel_unit = (long) base_unit;
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// integrate, first difference, rescale, convert to int
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double sum = 0.0;
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double next = 0.0;
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int const impulses_size = this->impulses_size();
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for ( i = 0; i < impulses_size; i++ )
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{
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impulses [i] = (short) floor( (next - sum) * rescale + 0.5 );
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sum += fimpulse [i];
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next += fimpulse [i + blip_res];
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}
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adjust_impulse();
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// volume might require rescaling
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double vol = volume_unit_;
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if ( vol )
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{
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volume_unit_ = 0.0;
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volume_unit( vol );
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}
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}
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void Blip_Synth_::volume_unit( double new_unit )
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{
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if ( new_unit != volume_unit_ )
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{
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// use default eq if it hasn't been set yet
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if ( !kernel_unit )
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treble_eq( -8.0 );
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volume_unit_ = new_unit;
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double factor = new_unit * (1L << blip_sample_bits) / kernel_unit;
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if ( factor > 0.0 )
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{
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int shift = 0;
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// if unit is really small, might need to attenuate kernel
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while ( factor < 2.0 )
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{
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shift++;
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factor *= 2.0;
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}
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if ( shift )
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{
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kernel_unit >>= shift;
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assert( kernel_unit > 0 ); // fails if volume unit is too low
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// keep values positive to avoid round-towards-zero of sign-preserving
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// right shift for negative values
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long offset = 0x8000 + (1 << (shift - 1));
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long offset2 = 0x8000 >> shift;
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for ( int i = impulses_size(); i--; )
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impulses [i] = (short) (((impulses [i] + offset) >> shift) - offset2);
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adjust_impulse();
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}
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}
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delta_factor = (int) floor( factor + 0.5 );
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//printf( "delta_factor: %d, kernel_unit: %d\n", delta_factor, kernel_unit );
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}
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}
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#endif
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long Blip_Buffer::read_samples( blip_sample_t* BLIP_RESTRICT out, long max_samples, int stereo )
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{
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long count = samples_avail();
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if ( count > max_samples )
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count = max_samples;
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if ( count )
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{
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int const bass = BLIP_READER_BASS( *this );
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BLIP_READER_BEGIN( reader, *this );
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if ( !stereo )
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{
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for ( blip_long n = count; n; --n )
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{
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blip_long s = BLIP_READER_READ( reader );
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if ( (blip_sample_t) s != s )
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s = 0x7FFF - (s >> 24);
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*out++ = (blip_sample_t) s;
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BLIP_READER_NEXT( reader, bass );
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}
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}
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else
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{
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for ( blip_long n = count; n; --n )
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{
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blip_long s = BLIP_READER_READ( reader );
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if ( (blip_sample_t) s != s )
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s = 0x7FFF - (s >> 24);
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*out = (blip_sample_t) s;
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out += 2;
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BLIP_READER_NEXT( reader, bass );
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}
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}
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BLIP_READER_END( reader, *this );
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remove_samples( count );
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}
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return count;
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}
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void Blip_Buffer::mix_samples( blip_sample_t const* in, long count )
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{
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if ( buffer_size_ == silent_buf_size )
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{
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assert( 0 );
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return;
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}
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buf_t_* out = buffer_ + (offset_ >> BLIP_BUFFER_ACCURACY) + blip_widest_impulse_ / 2;
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int const sample_shift = blip_sample_bits - 16;
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int prev = 0;
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while ( count-- )
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{
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blip_long s = (blip_long) *in++ << sample_shift;
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*out += s - prev;
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prev = s;
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++out;
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}
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*out -= prev;
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}
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