227 lines
6.1 KiB
C
227 lines
6.1 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 <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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#include "blargg_source.h"
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void Blip_init( struct Blip_Buffer* this )
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{
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this->factor_ = UINT_MAX/2 + 1;;
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this->buffer_center_ = NULL;
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this->buffer_size_ = 0;
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this->sample_rate_ = 0;
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this->bass_shift_ = 0;
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this->clock_rate_ = 0;
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this->bass_freq_ = 16;
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this->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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Blip_clear( this );
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}
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void Blip_clear( struct Blip_Buffer* this )
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{
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bool const entire_buffer = true;
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this->offset_ = 0;
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this->reader_accum_ = 0;
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this->modified = false;
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#if 0 // this is redundant as buffer is static and triggers -Waddress
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if ( this->buffer_ )
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#endif
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{
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int count = (entire_buffer ? this->buffer_size_ : Blip_samples_avail( this ));
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memset( this->buffer_, 0, (count + blip_buffer_extra_) * sizeof (delta_t) );
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}
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}
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blargg_err_t Blip_set_sample_rate( struct Blip_Buffer* this, int new_rate, int msec )
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{
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// Limit to maximum size that resampled time can represent
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int max_size = (((blip_resampled_time_t) -1) >> BLIP_BUFFER_ACCURACY) -
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blip_buffer_extra_ - 64; // TODO: -64 isn't needed
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int new_size = (new_rate * (msec + 1) + 999) / 1000;
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if ( new_size > max_size )
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new_size = max_size;
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// Resize buffer
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if ( this->buffer_size_ != new_size ) {
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this->buffer_center_ = this->buffer_ + BLIP_MAX_QUALITY/2;
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this->buffer_size_ = new_size;
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}
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// update things based on the sample rate
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this->sample_rate_ = new_rate;
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this->length_ = new_size * 1000 / new_rate - 1;
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if ( this->clock_rate_ )
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Blip_set_clock_rate( this, this->clock_rate_ );
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Blip_bass_freq( this, this->bass_freq_ );
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Blip_clear( this );
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return 0; // success
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}
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blip_resampled_time_t Blip_clock_rate_factor( struct Blip_Buffer* this, int rate )
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{
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int factor = (int) ( this->sample_rate_ * (1LL << BLIP_BUFFER_ACCURACY) / rate);
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assert( factor > 0 || !this->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_bass_freq( struct Blip_Buffer* this, int freq )
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{
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this->bass_freq_ = freq;
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int shift = 31;
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if ( freq > 0 && this->sample_rate_ )
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{
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shift = 13;
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int f = (freq << 16) / this->sample_rate_;
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while ( (f >>= 1) && --shift ) { }
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}
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this->bass_shift_ = shift;
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}
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void Blip_end_frame( struct Blip_Buffer* this, blip_time_t t )
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{
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this->offset_ += t * this->factor_;
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assert( Blip_samples_avail( this ) <= (int) this->buffer_size_ ); // time outside buffer length
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}
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int Blip_count_samples( struct Blip_Buffer* this, blip_time_t t )
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{
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blip_resampled_time_t last_sample = Blip_resampled_time( this, t ) >> BLIP_BUFFER_ACCURACY;
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blip_resampled_time_t first_sample = this->offset_ >> BLIP_BUFFER_ACCURACY;
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return (int) (last_sample - first_sample);
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}
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blip_time_t Blip_count_clocks( struct Blip_Buffer* this, int count )
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{
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if ( count > this->buffer_size_ )
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count = this->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 - this->offset_ + this->factor_ - 1) / this->factor_);
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}
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void Blip_remove_samples( struct Blip_Buffer* this, int count )
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{
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if ( count )
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{
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Blip_remove_silence( this, count );
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// copy remaining samples to beginning and clear old samples
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int remain = Blip_samples_avail( this ) + blip_buffer_extra_;
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memmove( this->buffer_, this->buffer_ + count, remain * sizeof *this->buffer_ );
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memset( this->buffer_ + remain, 0, count * sizeof *this->buffer_ );
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}
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}
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int Blip_read_samples( struct Blip_Buffer* this, blip_sample_t out_ [], int max_samples, bool stereo )
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{
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int count = Blip_samples_avail( this );
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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 = this->bass_shift_;
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delta_t const* reader = this->buffer_ + count;
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int reader_sum = this->reader_accum_;
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blip_sample_t* BLARGG_RESTRICT out = out_ + count;
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if ( stereo )
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out += count;
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int offset = -count;
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if ( !stereo )
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{
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do
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{
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int s = reader_sum >> delta_bits;
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reader_sum -= reader_sum >> bass;
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reader_sum += reader [offset];
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BLIP_CLAMP( s, s );
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out [offset] = (blip_sample_t) s;
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}
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while ( ++offset );
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}
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else
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{
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do
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{
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int s = reader_sum >> delta_bits;
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reader_sum -= reader_sum >> bass;
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reader_sum += reader [offset];
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BLIP_CLAMP( s, s );
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out [offset * 2] = (blip_sample_t) s;
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}
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while ( ++offset );
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}
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this->reader_accum_ = reader_sum;
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Blip_remove_samples( this, count );
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}
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return count;
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}
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void Blip_mix_samples( struct Blip_Buffer* this, blip_sample_t const in [], int count )
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{
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delta_t* out = this->buffer_center_ + (this->offset_ >> BLIP_BUFFER_ACCURACY);
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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 >= 0 )
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{
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int s = *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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// Blip_Synth
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void volume_unit( struct Blip_Synth* this, int new_unit )
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{
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this->delta_factor = (int) (new_unit * (1LL << blip_sample_bits) / FP_ONE_VOLUME);
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}
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void Synth_init( struct Blip_Synth* this )
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{
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this->buf = 0;
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this->last_amp = 0;
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this->delta_factor = 0;
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}
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