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#include "fftease.h"
void fftease_makewindows( t_float *H, t_float *A, t_float *S, int Nw, int N, int I )
{
int i ;
t_float sum ;
for ( i = 0 ; i < Nw ; i++ )
H[i] = A[i] = S[i] = 0.54 - 0.46*cos( TWOPI*i/(Nw - 1) ) ;
if ( Nw > N ) {
t_float x ;
x = -(Nw - 1)/2. ;
for ( i = 0 ; i < Nw ; i++, x += 1. )
if ( x != 0. ) {
A[i] *= N*sin( PI*x/N )/(PI*x) ;
if ( I )
S[i] *= I*sin( PI*x/I )/(PI*x) ;
}
}
for ( sum = i = 0 ; i < Nw ; i++ )
sum += A[i] ;
for ( i = 0 ; i < Nw ; i++ ) {
t_float afac = 2./sum ;
t_float sfac = Nw > N ? 1./afac : afac ;
A[i] *= afac ;
S[i] *= sfac ;
}
if ( Nw <= N && I ) {
for ( sum = i = 0 ; i < Nw ; i += I )
sum += S[i]*S[i] ;
for ( sum = 1./sum, i = 0 ; i < Nw ; i++ )
S[i] *= sum ;
}
}
void fftease_makehamming( t_float *H, t_float *A, t_float *S, int Nw, int N, int I, int odd )
{
int i;
t_float sum ;
if (odd) {
for ( i = 0 ; i < Nw ; i++ )
H[i] = A[i] = S[i] = sqrt(0.54 - 0.46*cos( TWOPI*i/(Nw - 1) ));
}
else {
for ( i = 0 ; i < Nw ; i++ )
H[i] = A[i] = S[i] = 0.54 - 0.46*cos( TWOPI*i/(Nw - 1) );
}
if ( Nw > N ) {
t_float x ;
x = -(Nw - 1)/2. ;
for ( i = 0 ; i < Nw ; i++, x += 1. )
if ( x != 0. ) {
A[i] *= N*sin( PI*x/N )/(PI*x) ;
if ( I )
S[i] *= I*sin( PI*x/I )/(PI*x) ;
}
}
for ( sum = i = 0 ; i < Nw ; i++ )
sum += A[i] ;
for ( i = 0 ; i < Nw ; i++ ) {
t_float afac = 2./sum ;
t_float sfac = Nw > N ? 1./afac : afac ;
A[i] *= afac ;
S[i] *= sfac ;
}
if ( Nw <= N && I ) {
for ( sum = i = 0 ; i < Nw ; i += I )
sum += S[i]*S[i] ;
for ( sum = 1./sum, i = 0 ; i < Nw ; i++ )
S[i] *= sum ;
}
}
void fftease_makehanning( t_float *H, t_float *A, t_float *S, int Nw, int N, int I, int odd )
{
int i;
t_float sum ;
if (odd) {
for ( i = 0 ; i < Nw ; i++ )
H[i] = A[i] = S[i] = sqrt(0.5 * (1. + cos(PI + TWOPI * i / (Nw - 1))));
}
else {
for ( i = 0 ; i < Nw ; i++ )
H[i] = A[i] = S[i] = 0.5 * (1. + cos(PI + TWOPI * i / (Nw - 1)));
}
if ( Nw > N ) {
t_float x ;
x = -(Nw - 1)/2. ;
for ( i = 0 ; i < Nw ; i++, x += 1. )
if ( x != 0. ) {
A[i] *= N*sin( PI*x/N )/(PI*x) ;
if ( I )
S[i] *= I*sin( PI*x/I )/(PI*x) ;
}
}
for ( sum = i = 0 ; i < Nw ; i++ )
sum += A[i] ;
for ( i = 0 ; i < Nw ; i++ ) {
t_float afac = 2./sum ;
t_float sfac = Nw > N ? 1./afac : afac ;
A[i] *= afac ;
S[i] *= sfac ;
}
if ( Nw <= N && I ) {
for ( sum = i = 0 ; i < Nw ; i += I )
sum += S[i]*S[i] ;
for ( sum = 1./sum, i = 0 ; i < Nw ; i++ )
S[i] *= sum ;
}
}
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