From 0ed7a8b68dd73e2b0473b8127aeca99f3bac9061 Mon Sep 17 00:00:00 2001 From: Thomas Grill Date: Wed, 1 Apr 2009 21:13:09 +0000 Subject: cleaned up grill externals - replaced with svn:externals to svn.grrrr.org/ext/trunk/ svn path=/trunk/; revision=10951 --- externals/grill/fftease/src/fft.c | 157 -------------------------------------- 1 file changed, 157 deletions(-) delete mode 100644 externals/grill/fftease/src/fft.c (limited to 'externals/grill/fftease/src/fft.c') diff --git a/externals/grill/fftease/src/fft.c b/externals/grill/fftease/src/fft.c deleted file mode 100644 index 844cddd5..00000000 --- a/externals/grill/fftease/src/fft.c +++ /dev/null @@ -1,157 +0,0 @@ -#include "pv.h" - - -/* If forward is true, rfft replaces 2*N real data points in x with - N complex values representing the positive frequency half of their - Fourier spectrum, with x[1] replaced with the real part of the Nyquist - frequency value. If forward is false, rfft expects x to contain a - positive frequency spectrum arranged as before, and replaces it with - 2*N real values. N MUST be a power of 2. */ -static void -bitreverse( float *x, int N ); - -static float sqr(float x) { return x*x; } - -void pv_rfft( float *x, int N, int forward ) -{ - float c1,c2, - h1r,h1i, - h2r,h2i, - wr,wi, - wpr,wpi, - temp, - theta; - float xr,xi; - int i, - i1,i2,i3,i4, - N2p1; - static int first = 1; - - if ( first ) { - - first = 0; - } - theta = PV_PI/N; - wr = 1.; - wi = 0.; - c1 = 0.5; - if ( forward ) { - c2 = -0.5; - pv_cfft( x, N, forward ); - xr = x[0]; - xi = x[1]; - } else { - c2 = 0.5; - theta = -theta; - xr = x[1]; - xi = 0.; - x[1] = 0.; - } - wpr = -2.*sqr( sin( 0.5*theta )); - wpi = sin( theta ); - N2p1 = (N<<1) + 1; - for ( i = 0; i <= N>>1; i++ ) { - i1 = i<<1; - i2 = i1 + 1; - i3 = N2p1 - i2; - i4 = i3 + 1; - if ( i == 0 ) { - h1r = c1*(x[i1] + xr ); - h1i = c1*(x[i2] - xi ); - h2r = -c2*(x[i2] + xi ); - h2i = c2*(x[i1] - xr ); - x[i1] = h1r + wr*h2r - wi*h2i; - x[i2] = h1i + wr*h2i + wi*h2r; - xr = h1r - wr*h2r + wi*h2i; - xi = -h1i + wr*h2i + wi*h2r; - } else { - h1r = c1*(x[i1] + x[i3] ); - h1i = c1*(x[i2] - x[i4] ); - h2r = -c2*(x[i2] + x[i4] ); - h2i = c2*(x[i1] - x[i3] ); - x[i1] = h1r + wr*h2r - wi*h2i; - x[i2] = h1i + wr*h2i + wi*h2r; - x[i3] = h1r - wr*h2r + wi*h2i; - x[i4] = -h1i + wr*h2i + wi*h2r; - } - wr = (temp = wr)*wpr - wi*wpi + wr; - wi = wi*wpr + temp*wpi + wi; - } - if ( forward ) - x[1] = xr; - else - pv_cfft( x, N, forward ); -} - -/* cfft replaces float array x containing NC complex values - (2*NC float values alternating real, imagininary, etc.) - by its Fourier transform if forward is true, or by its - inverse Fourier transform if forward is false, using a - recursive Fast Fourier transform method due to Danielson - and Lanczos. NC MUST be a power of 2. */ - -void pv_cfft( float *x, int NC, int forward ) -{ - float wr,wi, - wpr,wpi, - theta, - scale; - int mmax, - ND, - m, - i,j, - delta; - - ND = NC<<1; - bitreverse( x, ND ); - for ( mmax = 2; mmax < ND; mmax = delta ) { - delta = mmax<<1; - theta = PV_2PI/( forward? mmax : -mmax ); - wpr = -2.*sqr( sin( 0.5*theta )); - wpi = sin( theta ); - wr = 1.; - wi = 0.; - for ( m = 0; m < mmax; m += 2 ) { - register float rtemp, itemp; - for ( i = m; i < ND; i += delta ) { - j = i + mmax; - rtemp = wr*x[j] - wi*x[j+1]; - itemp = wr*x[j+1] + wi*x[j]; - x[j] = x[i] - rtemp; - x[j+1] = x[i+1] - itemp; - x[i] += rtemp; - x[i+1] += itemp; - } - wr = (rtemp = wr)*wpr - wi*wpi + wr; - wi = wi*wpr + rtemp*wpi + wi; - } - } - -/* scale output */ - - scale = forward ? 1./ND : 2.; - { register float *xi=x, *xe=x+ND; - while ( xi < xe ) - *xi++ *= scale; - } -} - -/* bitreverse places float array x containing N/2 complex values - into bit-reversed order */ - -void bitreverse( float *x, int N ) -{ - float rtemp,itemp; - int i,j, - m; - - for ( i = j = 0; i < N; i += 2, j += m ) { - if ( j > i ) { - rtemp = x[j]; itemp = x[j+1]; /* complex exchange */ - x[j] = x[i]; x[j+1] = x[i+1]; - x[i] = rtemp; x[i+1] = itemp; - } - for ( m = N>>1; m >= 2 && j >= m; m >>= 1 ) - j -= m; - } -} -- cgit v1.2.1