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78 lines
2.3 KiB
C++
78 lines
2.3 KiB
C++
/* interpolator.h: Does a linear interpolation between the points in the
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supplied samples to a TZX-friendly 3.5MHz
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Copyright (c) 2008 Fredrick Meunier
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$Id$
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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Author contact information:
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E-mail: fredm@spamcop.net
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*/
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#ifndef INTERPOLATOR_H
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#define INTERPOLATOR_H
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#include <math.h>
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#include <libspectrum.h>
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#include "importer/soundfile.h"
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class interpolator {
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public:
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interpolator( libspectrum_byte *samples, size_t samples_length, double rate,
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double source_rate ) :
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source_sample_rate(source_rate),
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sample_rate(rate),
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pulses(samples),
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source_length(samples_length) {
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length = floor( source_length * source_sample_rate/sample_rate );
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}
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double get_length() { return length; }
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libspectrum_byte get_sample( double tstates ) {
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// convert tstates to samples offsets
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double tstate_offset = tstates * sample_rate/source_sample_rate;
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size_t offset1 = (size_t)floor(tstate_offset);
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size_t offset2 = (size_t)ceil(tstate_offset);
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double distance = tstate_offset - offset1;
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// get samples
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libspectrum_byte sample1 = pulses[offset1];
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if( offset2 >= source_length ) offset2 = source_length - 1;
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libspectrum_byte sample2 = pulses[offset2];
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// if we have two samples, allocate final value based on
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// distance between both samples
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int difference = sample2 - sample1;
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return (libspectrum_byte) (sample1 + (difference * distance));
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}
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private:
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double source_sample_rate;
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double sample_rate;
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double length;
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libspectrum_byte *pulses;
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size_t source_length;
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};
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#endif /* #define INTERPOLATOR_H */
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