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/*
* Copyright (c) 1997-1999, 2003 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
*
*/
/* $Id: rexec2.c,v 1.20 2003/03/16 23:43:46 stevenj Exp $ */
/*
* rexec2.c -- alternate rfftw executor, specifically designed for the
* multidimensional transforms. Given an extra work array,
* expects complex data in FFTW_COMPLEX format, and does
* not destroy the input in hc2real transforms.
*/
#include "fftw-int.h"
#include "rfftw.h"
/* copies halfcomplex array in (contiguous) to fftw_complex array out. */
void rfftw_hc2c(int n, fftw_real *in, fftw_complex *out, int ostride)
{
int n2 = (n + 1) / 2;
int i = 1;
c_re(out[0]) = in[0];
c_im(out[0]) = 0.0;
for (; i < ((n2 - 1) & 3) + 1; ++i) {
c_re(out[i * ostride]) = in[i];
c_im(out[i * ostride]) = in[n - i];
}
for (; i < n2; i += 4) {
fftw_real r0, r1, r2, r3;
fftw_real i0, i1, i2, i3;
r0 = in[i];
r1 = in[i + 1];
r2 = in[i + 2];
r3 = in[i + 3];
i3 = in[n - (i + 3)];
i2 = in[n - (i + 2)];
i1 = in[n - (i + 1)];
i0 = in[n - i];
c_re(out[i * ostride]) = r0;
c_im(out[i * ostride]) = i0;
c_re(out[(i + 1) * ostride]) = r1;
c_im(out[(i + 1) * ostride]) = i1;
c_re(out[(i + 2) * ostride]) = r2;
c_im(out[(i + 2) * ostride]) = i2;
c_re(out[(i + 3) * ostride]) = r3;
c_im(out[(i + 3) * ostride]) = i3;
}
if ((n & 1) == 0) { /* store the Nyquist frequency */
c_re(out[n2 * ostride]) = in[n2];
c_im(out[n2 * ostride]) = 0.0;
}
}
/* reverse of rfftw_hc2c */
void rfftw_c2hc(int n, fftw_complex *in, int istride, fftw_real *out)
{
int n2 = (n + 1) / 2;
int i = 1;
out[0] = c_re(in[0]);
for (; i < ((n2 - 1) & 3) + 1; ++i) {
out[i] = c_re(in[i * istride]);
out[n - i] = c_im(in[i * istride]);
}
for (; i < n2; i += 4) {
fftw_real r0, r1, r2, r3;
fftw_real i0, i1, i2, i3;
r0 = c_re(in[i * istride]);
i0 = c_im(in[i * istride]);
r1 = c_re(in[(i + 1) * istride]);
i1 = c_im(in[(i + 1) * istride]);
r2 = c_re(in[(i + 2) * istride]);
i2 = c_im(in[(i + 2) * istride]);
r3 = c_re(in[(i + 3) * istride]);
i3 = c_im(in[(i + 3) * istride]);
out[i] = r0;
out[i + 1] = r1;
out[i + 2] = r2;
out[i + 3] = r3;
out[n - (i + 3)] = i3;
out[n - (i + 2)] = i2;
out[n - (i + 1)] = i1;
out[n - i] = i0;
}
if ((n & 1) == 0) /* store the Nyquist frequency */
out[n2] = c_re(in[n2 * istride]);
}
/*
* in: array of n real numbers (* howmany).
* out: array of n/2 + 1 complex numbers (* howmany).
* work: array of n real numbers (stride 1)
*
* We must have out != in if dist < stride.
*/
void rfftw_real2c_aux(fftw_plan plan, int howmany,
fftw_real *in, int istride, int idist,
fftw_complex *out, int ostride, int odist,
fftw_real *work)
{
fftw_plan_node *p = plan->root;
int j;
switch (p->type) {
case FFTW_REAL2HC:
{
fftw_real2hc_codelet *codelet = p->nodeu.real2hc.codelet;
int n = plan->n;
int n2 = (n & 1) ? 0 : (n + 1) / 2;
HACK_ALIGN_STACK_ODD;
for (j = 0; j < howmany; ++j, out += odist) {
codelet(in + j * idist,
&c_re(*out),
&c_im(*out),
istride, ostride * 2, ostride * 2);
c_im(out[0]) = 0.0;
c_im(out[n2 * ostride]) = 0.0;
}
break;
}
default:
{
int n = plan->n;
fftw_recurse_kind recurse_kind = plan->recurse_kind;
for (j = 0; j < howmany; ++j, in += idist, out += odist) {
rfftw_executor_simple(n, in, work, p, istride, 1,
recurse_kind);
rfftw_hc2c(n, work, out, ostride);
}
break;
}
}
}
/*
* in: array of n/2 + 1 complex numbers (* howmany).
* out: array of n real numbers (* howmany).
* work: array of n real numbers (stride 1)
*
* We must have out != in if dist < stride.
*/
void rfftw_c2real_aux(fftw_plan plan, int howmany,
fftw_complex *in, int istride, int idist,
fftw_real *out, int ostride, int odist,
fftw_real *work)
{
fftw_plan_node *p = plan->root;
switch (p->type) {
case FFTW_HC2REAL:
{
fftw_hc2real_codelet *codelet = p->nodeu.hc2real.codelet;
int j;
HACK_ALIGN_STACK_ODD;
for (j = 0; j < howmany; ++j)
codelet(&c_re(*(in + j * idist)),
&c_im(*(in + j * idist)),
out + j * odist,
istride * 2, istride * 2, ostride);
break;
}
default:
{
int j, n = plan->n;
fftw_recurse_kind recurse_kind = plan->recurse_kind;
for (j = 0; j < howmany; ++j, in += idist, out += odist) {
rfftw_c2hc(n, in, istride, work);
rfftw_executor_simple(n, work, out, p, 1, ostride,
recurse_kind);
}
break;
}
}
}
/*
* The following two functions are similar to the ones above, BUT:
*
* work must contain n * howmany elements (stride 1)
*
* Can handle out == in for any stride/dist.
*/
void rfftw_real2c_overlap_aux(fftw_plan plan, int howmany,
fftw_real *in, int istride, int idist,
fftw_complex *out, int ostride, int odist,
fftw_real *work)
{
int n = plan->n;
int j;
rfftw(plan, howmany, in, istride, idist, work, 1, n);
/* copy from work to out: */
for (j = 0; j < howmany; ++j, work += n, out += odist)
rfftw_hc2c(n, work, out, ostride);
}
void rfftw_c2real_overlap_aux(fftw_plan plan, int howmany,
fftw_complex *in, int istride, int idist,
fftw_real *out, int ostride, int odist,
fftw_real *work)
{
int n = plan->n;
int j;
/* copy from in to work: */
for (j = 0; j < howmany; ++j, in += idist)
rfftw_c2hc(n, in, istride, work + j * n);
rfftw(plan, howmany, work, 1, n, out, ostride, odist);
}
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