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rfftwnd.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
 *
 */

/* $Id: rfftwnd.c,v 1.33 1999/11/02 23:52:02 stevenj Exp $ */

#include <fftw-int.h>
#include <rfftw.h>

/********************** prototypes for rexec2 routines **********************/

extern 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);
extern 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);
extern 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);
extern 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);

/********************** Initializing the RFFTWND Plan ***********************/

/*
 * Create an fftwnd_plan specialized for specific arrays.  (These
 * arrays are ignored, however, if they are NULL or if the flags
 * do not include FFTW_MEASURE.)  The main advantage of being
 * provided arrays like this is that we can do runtime timing
 * measurements of our options, without worrying about allocating
 * excessive scratch space. 
 */
fftwnd_plan rfftwnd_create_plan_specific(int rank, const int *n,
                               fftw_direction dir, int flags,
                               fftw_real *in, int istride,
                               fftw_real *out, int ostride)
{
     fftwnd_plan p;
     int i;
     int rflags = flags & ~FFTW_IN_PLACE;
     /* note that we always do rfftw transforms out-of-place in rexec2.c */

     if (flags & FFTW_IN_PLACE) {
        out = NULL;
        ostride = istride;
     }
     istride = ostride = 1;   /* 
                         * strides don't work yet, since it is not 
                         * clear whether they apply to real 
                         * or complex data 
                         */

     if (!(p = fftwnd_create_plan_aux(rank, n, dir, flags)))
        return 0;

     for (i = 0; i < rank - 1; ++i)
        p->n_after[i] = (n[rank - 1]/2 + 1) * (p->n_after[i] / n[rank - 1]);
     if (rank > 0)
        p->n[rank - 1] = n[rank - 1] / 2 + 1;

     p->plans = fftwnd_new_plan_array(rank);
     if (rank > 0 && !p->plans) {
        rfftwnd_destroy_plan(p);
        return 0;
     }
     if (rank > 0) {
        p->plans[rank - 1] = rfftw_create_plan(n[rank - 1], dir, rflags);
        if (!p->plans[rank - 1]) {
             rfftwnd_destroy_plan(p);
             return 0;
        }
     }
     if (rank > 1) {
        if (!(flags & FFTW_MEASURE) || in == 0
            || (!p->is_in_place && out == 0)) {
             if (!fftwnd_create_plans_generic(p->plans, rank - 1, n,
                                 dir, flags | FFTW_IN_PLACE)) {
                rfftwnd_destroy_plan(p);
                return 0;
             }
        } else if (dir == FFTW_COMPLEX_TO_REAL || (flags & FFTW_IN_PLACE)) {
             if (!fftwnd_create_plans_specific(p->plans, rank - 1, n,
                                     p->n_after,
                                    dir, flags | FFTW_IN_PLACE,
                                     (fftw_complex *) in,
                                     istride,
                                     0, 0)) {
                rfftwnd_destroy_plan(p);
                return 0;
             }
        } else {
             if (!fftwnd_create_plans_specific(p->plans, rank - 1, n,
                                     p->n_after,
                                    dir, flags | FFTW_IN_PLACE,
                                     (fftw_complex *) out,
                                     ostride,
                                     0, 0)) {
                rfftwnd_destroy_plan(p);
                return 0;
             }
        }
     }
     p->nbuffers = 0;
     p->nwork = fftwnd_work_size(rank, p->n, flags | FFTW_IN_PLACE,
                         p->nbuffers + 1);
     if (p->nwork && !(flags & FFTW_THREADSAFE)) {
        p->work = (fftw_complex *) fftw_malloc(p->nwork
                                     * sizeof(fftw_complex));
        if (!p->work) {
             rfftwnd_destroy_plan(p);
             return 0;
        }
     }
     return p;
}

fftwnd_plan rfftw2d_create_plan_specific(int nx, int ny,
                               fftw_direction dir, int flags,
                               fftw_real *in, int istride,
                               fftw_real *out, int ostride)
{
     int n[2];

     n[0] = nx;
     n[1] = ny;

     return rfftwnd_create_plan_specific(2, n, dir, flags,
                               in, istride, out, ostride);
}

fftwnd_plan rfftw3d_create_plan_specific(int nx, int ny, int nz,
                               fftw_direction dir, int flags,
                               fftw_real *in, int istride,
                               fftw_real *out, int ostride)
{
     int n[3];

     n[0] = nx;
     n[1] = ny;
     n[2] = nz;

     return rfftwnd_create_plan_specific(3, n, dir, flags,
                               in, istride, out, ostride);
}

/* Create a generic fftwnd plan: */

fftwnd_plan rfftwnd_create_plan(int rank, const int *n,
                        fftw_direction dir, int flags)
{
     return rfftwnd_create_plan_specific(rank, n, dir, flags, 0, 1, 0, 1);
}

fftwnd_plan rfftw2d_create_plan(int nx, int ny,
                        fftw_direction dir, int flags)
{
     return rfftw2d_create_plan_specific(nx, ny, dir, flags, 0, 1, 0, 1);
}

fftwnd_plan rfftw3d_create_plan(int nx, int ny, int nz,
                        fftw_direction dir, int flags)
{
     return rfftw3d_create_plan_specific(nx, ny, nz, dir, flags, 0, 1, 0, 1);
}

/************************ Freeing the RFFTWND Plan ************************/

void rfftwnd_destroy_plan(fftwnd_plan plan)
{
     fftwnd_destroy_plan(plan);
}

/************************ Printing the RFFTWND Plan ************************/

void rfftwnd_fprint_plan(FILE *f, fftwnd_plan plan)
{
     fftwnd_fprint_plan(f, plan);
}

void rfftwnd_print_plan(fftwnd_plan plan)
{
     rfftwnd_fprint_plan(stdout, plan);
}

/*********** Computing the N-Dimensional FFT: Auxiliary Routines ************/

void rfftwnd_real2c_aux(fftwnd_plan p, int cur_dim,
                  fftw_real *in, int istride,
                  fftw_complex *out, int ostride,
                  fftw_real *work)
{
     int n_after = p->n_after[cur_dim], n = p->n[cur_dim];

     if (cur_dim == p->rank - 2) {
        /* just do the last dimension directly: */
        if (p->is_in_place)
             rfftw_real2c_aux(p->plans[p->rank - 1], n,
                        in, istride, (n_after * istride) * 2,
                        out, istride, n_after * istride,
                        work);
        else
             rfftw_real2c_aux(p->plans[p->rank - 1], n,
                   in, istride, p->plans[p->rank - 1]->n * istride,
                        out, ostride, n_after * ostride,
                        work);
     } else {                 /* we have at least two dimensions to go */
        int nr = p->plans[p->rank - 1]->n;
        int n_after_r = p->is_in_place ? n_after * 2 
             : nr * (n_after / (nr/2 + 1));
        int i;

        /* 
         * process the subsequent dimensions recursively, in hyperslabs,
         * to get maximum locality: 
         */
        for (i = 0; i < n; ++i)
             rfftwnd_real2c_aux(p, cur_dim + 1,
                          in + i * n_after_r * istride, istride,
                       out + i * n_after * ostride, ostride, work);
     }

     /* do the current dimension (in-place): */
     fftw(p->plans[cur_dim], n_after,
        out, n_after * ostride, ostride,
        (fftw_complex *) work, 1, 0);
     /* I hate this cast */
}

void rfftwnd_c2real_aux(fftwnd_plan p, int cur_dim,
                  fftw_complex *in, int istride,
                  fftw_real *out, int ostride,
                  fftw_real *work)
{
     int n_after = p->n_after[cur_dim], n = p->n[cur_dim];

     /* do the current dimension (in-place): */
     fftw(p->plans[cur_dim], n_after,
        in, n_after * istride, istride,
        (fftw_complex *) work, 1, 0);

     if (cur_dim == p->rank - 2) {
        /* just do the last dimension directly: */
        if (p->is_in_place)
             rfftw_c2real_aux(p->plans[p->rank - 1], n,
                        in, istride, n_after * istride,
                        out, istride, (n_after * istride) * 2,
                        work);
        else
             rfftw_c2real_aux(p->plans[p->rank - 1], n,
                        in, istride, n_after * istride,
                  out, ostride, p->plans[p->rank - 1]->n * ostride,
                        work);
     } else {                 /* we have at least two dimensions to go */
        int nr = p->plans[p->rank - 1]->n;
        int n_after_r = p->is_in_place ? n_after * 2 : 
             nr * (n_after / (nr/2 + 1));
        int i;

        /* 
         * process the subsequent dimensions recursively, in hyperslabs,
         * to get maximum locality: 
         */
        for (i = 0; i < n; ++i)
             rfftwnd_c2real_aux(p, cur_dim + 1,
                          in + i * n_after * istride, istride,
                     out + i * n_after_r * ostride, ostride, work);
     }
}

/*
 * alternate version of rfftwnd_aux -- this version pushes the howmany
 * loop down to the leaves of the computation, for greater locality
 * in cases where dist < stride.  It is also required for correctness
 * if in==out, and we must call a special version of the executor.
 * Note that work must point to 'howmany' copies of its data
 * if in == out. 
 */

void rfftwnd_real2c_aux_howmany(fftwnd_plan p, int cur_dim,
                        int howmany,
                        fftw_real *in, int istride, int idist,
                        fftw_complex *out, int ostride, int odist,
                        fftw_complex *work)
{
     int n_after = p->n_after[cur_dim], n = p->n[cur_dim];
     int k;

     if (cur_dim == p->rank - 2) {
        /* just do the last dimension directly: */
        if (p->is_in_place)
             for (k = 0; k < n; ++k)
                rfftw_real2c_overlap_aux(p->plans[p->rank - 1], howmany,
                              in + (k * n_after * istride) * 2,
                                   istride, idist,
                                 out + (k * n_after * ostride),
                                   ostride, odist,
                                   (fftw_real *) work);
        else {
             int nlast = p->plans[p->rank - 1]->n;
             for (k = 0; k < n; ++k)
                rfftw_real2c_aux(p->plans[p->rank - 1], howmany,
                             in + k * nlast * istride,
                             istride, idist,
                             out + k * n_after * ostride,
                             ostride, odist,
                             (fftw_real *) work);
        }
     } else {                 /* we have at least two dimensions to go */
        int nr = p->plans[p->rank - 1]->n;
        int n_after_r = p->is_in_place ? n_after * 2 : 
             nr * (n_after / (nr/2 + 1));
        int i;

        /* 
         * process the subsequent dimensions recursively, in hyperslabs,
         * to get maximum locality: 
         */
        for (i = 0; i < n; ++i)
             rfftwnd_real2c_aux_howmany(p, cur_dim + 1, howmany,
                      in + i * n_after_r * istride, istride, idist,
                       out + i * n_after * ostride, ostride, odist,
                                work);
     }

     /* do the current dimension (in-place): */
     for (k = 0; k < n_after; ++k)
        fftw(p->plans[cur_dim], howmany,
             out + k * ostride, n_after * ostride, odist,
             work, 1, 0);
}

void rfftwnd_c2real_aux_howmany(fftwnd_plan p, int cur_dim,
                        int howmany,
                        fftw_complex *in, int istride, int idist,
                        fftw_real *out, int ostride, int odist,
                        fftw_complex *work)
{
     int n_after = p->n_after[cur_dim], n = p->n[cur_dim];
     int k;

     /* do the current dimension (in-place): */
     for (k = 0; k < n_after; ++k)
        fftw(p->plans[cur_dim], howmany,
             in + k * istride, n_after * istride, idist,
             work, 1, 0);

     if (cur_dim == p->rank - 2) {
        /* just do the last dimension directly: */
        if (p->is_in_place)
             for (k = 0; k < n; ++k)
                rfftw_c2real_overlap_aux(p->plans[p->rank - 1], howmany,
                                   in + (k * n_after * istride),
                                   istride, idist,
                               out + (k * n_after * ostride) * 2,
                                   ostride, odist,
                                   (fftw_real *) work);
        else {
             int nlast = p->plans[p->rank - 1]->n;
             for (k = 0; k < n; ++k)
                rfftw_c2real_aux(p->plans[p->rank - 1], howmany,
                             in + k * n_after * istride,
                             istride, idist,
                             out + k * nlast * ostride,
                             ostride, odist,
                             (fftw_real *) work);
        }
     } else {                 /* we have at least two dimensions to go */
        int nr = p->plans[p->rank - 1]->n;
        int n_after_r = p->is_in_place ? n_after * 2
             : nr * (n_after / (nr/2 + 1));
        int i;

        /* 
         * process the subsequent dimensions recursively, in hyperslabs,
         * to get maximum locality: 
         */
        for (i = 0; i < n; ++i)
             rfftwnd_c2real_aux_howmany(p, cur_dim + 1, howmany,
                        in + i * n_after * istride, istride, idist,
                     out + i * n_after_r * ostride, ostride, odist,
                                work);
     }
}

/********** Computing the N-Dimensional FFT: User-Visible Routines **********/

void rfftwnd_real_to_complex(fftwnd_plan p, int howmany,
                       fftw_real *in, int istride, int idist,
                       fftw_complex *out, int ostride, int odist)
{
     fftw_complex *work = p->work;
     int rank = p->rank;
     int free_work = 0;

     if (p->dir != FFTW_REAL_TO_COMPLEX)
        fftw_die("rfftwnd_real_to_complex with complex-to-real plan");

#ifdef FFTW_DEBUG
     if (p->rank > 0 && (p->plans[0]->flags & FFTW_THREADSAFE)
       && p->nwork && p->work)
        fftw_die("bug with FFTW_THREADSAFE flag");
#endif

     if (p->is_in_place) {
        ostride = istride;
        odist = (idist == 1 && idist < istride) ? 1 : (idist / 2);  /* ugh */
        out = (fftw_complex *) in;
        if (howmany > 1 && istride > idist && rank > 0) {
             int new_nwork;

             new_nwork = p->n[rank - 1] * howmany;
             if (new_nwork > p->nwork) {
                work = (fftw_complex *)
                  fftw_malloc(sizeof(fftw_complex) * new_nwork);
                if (!work)
                   fftw_die("error allocating work array");
                free_work = 1;
             }
        }
     }
     if (p->nwork && !work) {
        work = (fftw_complex *) fftw_malloc(sizeof(fftw_complex) * p->nwork);
        free_work = 1;
     }
     switch (rank) {
       case 0:
            break;
       case 1:
            if (p->is_in_place && howmany > 1 && istride > idist)
               rfftw_real2c_overlap_aux(p->plans[0], howmany,
                                  in, istride, idist,
                                  out, ostride, odist,
                                  (fftw_real *) work);
            else
               rfftw_real2c_aux(p->plans[0], howmany,
                            in, istride, idist,
                            out, ostride, odist,
                            (fftw_real *) work);
            break;
       default:         /* rank >= 2 */
            {
               if (howmany > 1 && ostride > odist)
                  rfftwnd_real2c_aux_howmany(p, 0, howmany,
                                       in, istride, idist,
                                       out, ostride, odist,
                                       work);
               else {
                  int i;

                  for (i = 0; i < howmany; ++i)
                       rfftwnd_real2c_aux(p, 0,
                                    in + i * idist, istride,
                                    out + i * odist, ostride,
                                    (fftw_real *) work);
               }
            }
     }

     if (free_work)
        fftw_free(work);
}

void rfftwnd_complex_to_real(fftwnd_plan p, int howmany,
                       fftw_complex *in, int istride, int idist,
                       fftw_real *out, int ostride, int odist)
{
     fftw_complex *work = p->work;
     int rank = p->rank;
     int free_work = 0;

     if (p->dir != FFTW_COMPLEX_TO_REAL)
        fftw_die("rfftwnd_complex_to_real with real-to-complex plan");

#ifdef FFTW_DEBUG
     if (p->rank > 0 && (p->plans[0]->flags & FFTW_THREADSAFE)
       && p->nwork && p->work)
        fftw_die("bug with FFTW_THREADSAFE flag");
#endif

     if (p->is_in_place) {
        ostride = istride;
        odist = idist;
        odist = (idist == 1 && idist < istride) ? 1 : (idist * 2);  /* ugh */
        out = (fftw_real *) in;
        if (howmany > 1 && istride > idist && rank > 0) {
             int new_nwork = p->n[rank - 1] * howmany;
             if (new_nwork > p->nwork) {
                work = (fftw_complex *)
                  fftw_malloc(sizeof(fftw_complex) * new_nwork);
                if (!work)
                   fftw_die("error allocating work array");
                free_work = 1;
             }
        }
     }
     if (p->nwork && !work) {
        work = (fftw_complex *) fftw_malloc(sizeof(fftw_complex) * p->nwork);
        free_work = 1;
     }
     switch (rank) {
       case 0:
            break;
       case 1:
            if (p->is_in_place && howmany > 1 && istride > idist)
               rfftw_c2real_overlap_aux(p->plans[0], howmany,
                                  in, istride, idist,
                                  out, ostride, odist,
                                  (fftw_real *) work);
            else
               rfftw_c2real_aux(p->plans[0], howmany,
                            in, istride, idist,
                            out, ostride, odist,
                            (fftw_real *) work);
            break;
       default:         /* rank >= 2 */
            {
               if (howmany > 1 && ostride > odist)
                  rfftwnd_c2real_aux_howmany(p, 0, howmany,
                                       in, istride, idist,
                                       out, ostride, odist,
                                       work);
               else {
                  int i;

                  for (i = 0; i < howmany; ++i)
                       rfftwnd_c2real_aux(p, 0,
                                    in + i * idist, istride,
                                    out + i * odist, ostride,
                                    (fftw_real *) work);
               }
            }
     }

     if (free_work)
        fftw_free(work);
}

void rfftwnd_one_real_to_complex(fftwnd_plan p,
                         fftw_real *in, fftw_complex *out)
{
     rfftwnd_real_to_complex(p, 1, in, 1, 1, out, 1, 1);
}

void rfftwnd_one_complex_to_real(fftwnd_plan p,
                         fftw_complex *in, fftw_real *out)
{
     rfftwnd_complex_to_real(p, 1, in, 1, 1, out, 1, 1);
}

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