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hmm?

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This commit is contained in:
tildearrow 2023-09-07 23:37:17 -05:00
parent a4698dc911
commit d81a181ba5
3 changed files with 33 additions and 3 deletions
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23
src/engine/filter.cpp
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@ -26,6 +26,7 @@ float* DivFilterTables::cubicTable=NULL;
float* DivFilterTables::sincTable=NULL;
float* DivFilterTables::sincTable8=NULL;
float* DivFilterTables::sincIntegralTable=NULL;
float* DivFilterTables::sincIntegralSmallTable=NULL;
// portions from Schism Tracker (scripts/lutgen.c)
// licensed under same license as this program.
@ -106,3 +107,25 @@ float* DivFilterTables::getSincIntegralTable() {
}
return sincIntegralTable;
}
float* DivFilterTables::getSincIntegralSmallTable() {
if (sincIntegralSmallTable==NULL) {
logD("initializing small sinc integral table.");
sincIntegralSmallTable=new float[256];
sincIntegralSmallTable[0]=-0.5f;
for (int i=1; i<256; i++) {
int mapped=((i&31)<<3)|(i>>5);
int mappedPrev=(((i-1)&31)<<3)|((i-1)>>5);
double x=(double)i*M_PI/32.0;
double sinc=sin(x)/x;
sincIntegralSmallTable[mapped]=sincIntegralSmallTable[mappedPrev]+(sinc/32.0);
}
for (int i=0; i<256; i++) {
int mapped=((i&31)<<3)|(i>>5);
sincIntegralSmallTable[mapped]*=pow(cos(M_PI*(double)i/512.0),2.0);
}
}
return sincIntegralSmallTable;
}

7
src/engine/filter.h
View file

@ -23,6 +23,7 @@ class DivFilterTables {
static float* sincTable;
static float* sincTable8;
static float* sincIntegralTable;
static float* sincIntegralSmallTable;
/**
* get a 1024x4 cubic spline table.
@ -47,4 +48,10 @@ class DivFilterTables {
* @return the table.
*/
static float* getSincIntegralTable();
/**
* get a 32x8 one-side sine-windowed sinc integral table.
* @return the table.
*/
static float* getSincIntegralSmallTable();
};