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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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