ref: 4f9a9087f16b92662389be3dc0589629359ac8a4
dir: /libfaad/fftw/generic.c/
/*
* Copyright (c) 1997-1999 Massachusetts Institute of Technology
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
/*
*
* generic.c -- "generic" codelets. They work for all n (and they are
* slow)
*/
#include <fftw-int.h>
#include <stdlib.h>
void fftw_twiddle_generic(fftw_complex *A, const fftw_complex *W,
int m, int r, int n, int stride)
{
int i, j, k;
const fftw_complex *jp;
fftw_complex *kp;
fftw_complex *tmp = (fftw_complex *)
fftw_malloc(r * sizeof(fftw_complex));
for (i = 0; i < m; ++i) {
for (k = 0, kp = tmp; k < r; ++k, kp++) {
fftw_real r0, i0, rt, it, rw, iw;
int l1 = i + m * k;
int l0;
r0 = i0 = 0.0;
for (j = 0, jp = A + i * stride, l0 = 0; j < r; ++j,
jp += m * stride) {
rw = c_re(W[l0]);
iw = c_im(W[l0]);
rt = c_re(*jp);
it = c_im(*jp);
r0 += rt * rw - it * iw;
i0 += rt * iw + it * rw;
l0 += l1;
if (l0 >= n)
l0 -= n;
}
c_re(*kp) = r0;
c_im(*kp) = i0;
}
for (k = 0, kp = A + i * stride; k < r; ++k, kp += m * stride)
*kp = tmp[k];
}
fftw_free(tmp);
}
void fftwi_twiddle_generic(fftw_complex *A, const fftw_complex *W,
int m, int r, int n, int stride)
{
int i, j, k;
const fftw_complex *jp;
fftw_complex *kp;
fftw_complex *tmp = (fftw_complex *)
fftw_malloc(r * sizeof(fftw_complex));
for (i = 0; i < m; ++i) {
for (k = 0, kp = tmp; k < r; ++k, kp++) {
fftw_real r0, i0, rt, it, rw, iw;
int l1 = i + m * k;
int l0;
r0 = i0 = 0.0;
for (j = 0, jp = A + i * stride, l0 = 0; j < r; ++j,
jp += m * stride) {
rw = c_re(W[l0]);
iw = c_im(W[l0]);
rt = c_re(*jp);
it = c_im(*jp);
r0 += rt * rw + it * iw;
i0 += it * rw - rt * iw;
l0 += l1;
if (l0 >= n)
l0 -= n;
}
c_re(*kp) = r0;
c_im(*kp) = i0;
}
for (k = 0, kp = A + i * stride; k < r; ++k, kp += m * stride)
*kp = tmp[k];
}
fftw_free(tmp);
}