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GUI: sample resampling

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tildearrow 2022-03-20 03:14:00 -05:00
parent 90a18611cd
commit 03cb910e93
6 changed files with 517 additions and 4 deletions
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88
src/engine/filter.cpp Normal file
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/**
* Furnace Tracker - multi-system chiptune tracker
* Copyright (C) 2021-2022 tildearrow and contributors
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <stddef.h>
#define _USE_MATH_DEFINES
#include <math.h>
#include "filter.h"
#include "../ta-log.h"
float* DivFilterTables::cubicTable=NULL;
float* DivFilterTables::sincTable=NULL;
float* DivFilterTables::sincIntegralTable=NULL;
// portions from Schism Tracker (scripts/lutgen.c)
// licensed under same license as this program.
float* DivFilterTables::getCubicTable() {
if (cubicTable==NULL) {
logD("initializing cubic spline table.\n");
cubicTable=new float[4096];
for (int i=0; i<1024; i++) {
float x=(float)i/1024.0;
cubicTable[(i<<2)]=-0.5*pow(x,3)+1.0*pow(x,2)-0.5*x;
cubicTable[1+(i<<2)]=1.5*pow(x,3)-2.5*pow(x,2)+1.0;
cubicTable[2+(i<<2)]=-1.5*pow(x,3)+2.0*pow(x,2)+0.5*x;
cubicTable[3+(i<<2)]=0.5*pow(x,3)-0.5*pow(x,2);
}
}
return cubicTable;
}
float* DivFilterTables:: getSincTable() {
if (sincTable==NULL) {
logD("initializing sinc table.\n");
sincTable=new float[65536];
sincTable[0]=1.0f;
for (int i=1; i<65536; i++) {
int mapped=((i&8191)<<3)|(i>>13);
double x=(double)i*M_PI/8192.0;
sincTable[mapped]=sin(x)/x;
}
for (int i=0; i<65536; i++) {
int mapped=((i&8191)<<3)|(i>>13);
sincTable[mapped]*=pow(cos(M_PI*(double)i/131072.0),2.0);
}
}
return sincTable;
}
float* DivFilterTables::getSincIntegralTable() {
if (sincIntegralTable==NULL) {
logD("initializing sinc integral table.\n");
sincIntegralTable=new float[65536];
sincIntegralTable[0]=-0.5f;
for (int i=1; i<65536; i++) {
int mapped=((i&8191)<<3)|(i>>13);
int mappedPrev=(((i-1)&8191)<<3)|((i-1)>>13);
double x=(double)i*M_PI/8192.0;
double sinc=sin(x)/x;
sincIntegralTable[mapped]=sincIntegralTable[mappedPrev]+(sinc/8192.0);
}
for (int i=0; i<65536; i++) {
int mapped=((i&8191)<<3)|(i>>13);
sincIntegralTable[mapped]*=pow(cos(M_PI*(double)i/131072.0),2.0);
}
}
return sincIntegralTable;
}