/*

 * Copyright (c) 2003, 2007-14 Matteo Frigo

 * Copyright (c) 2003, 2007-14 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

 *

 */

/* plans for RDFT2 of rank >= 2 (multidimensional) */

#include "rdft/rdft.h"

#include "dft/dft.h"

typedef struct {

     solver super;

     int spltrnk;

     const int *buddies;

     size_t nbuddies;

} S;

typedef struct {

     plan_dft super;

     plan *cldr, *cldc;

     const S *solver;

} P;

static void apply_r2hc(const plan *ego_, R *r0, R *r1, R *cr, R *ci)

{

     const P *ego = (const P *) ego_;

     {

    plan_rdft2 *cldr = (plan_rdft2 *) ego->cldr;

    cldr->apply((plan *) cldr, r0, r1, cr, ci);

     }

     {

    plan_dft *cldc = (plan_dft *) ego->cldc;

    cldc->apply((plan *) cldc, cr, ci, cr, ci);

     }

}

static void apply_hc2r(const plan *ego_, R *r0, R *r1, R *cr, R *ci)

{

     const P *ego = (const P *) ego_;

     {

    plan_dft *cldc = (plan_dft *) ego->cldc;

    cldc->apply((plan *) cldc, ci, cr, ci, cr);

     }

     {

    plan_rdft2 *cldr = (plan_rdft2 *) ego->cldr;

    cldr->apply((plan *) cldr, r0, r1, cr, ci);

     }

}

static void awake(plan *ego_, enum wakefulness wakefulness)

{

     P *ego = (P *) ego_;

     X(plan_awake)(ego->cldr, wakefulness);

     X(plan_awake)(ego->cldc, wakefulness);

}

static void destroy(plan *ego_)

{

     P *ego = (P *) ego_;

     X(plan_destroy_internal)(ego->cldr);

     X(plan_destroy_internal)(ego->cldc);

}

static void print(const plan *ego_, printer *p)

{

     const P *ego = (const P *) ego_;

     const S *s = ego->solver;

     p->print(p, "(rdft2-rank>=2/%d%(%p%)%(%p%))", 

        s->spltrnk, ego->cldr, ego->cldc);

}

static int picksplit(const S *ego, const tensor *sz, int *rp)

{

     A(sz->rnk > 1); /* cannot split rnk <= 1 */

     if (!X(pickdim)(ego->spltrnk, ego->buddies, ego->nbuddies, sz, 1, rp))

          return 0;

     *rp += 1; /* convert from dim. index to rank */

     if (*rp >= sz->rnk) /* split must reduce rank */

          return 0;

     return 1;

}

static int applicable0(const solver *ego_, const problem *p_, int *rp,

           const planner *plnr)

{

     const problem_rdft2 *p = (const problem_rdft2 *) p_;

     const S *ego = (const S *)ego_;

     return (1

       && FINITE_RNK(p->sz->rnk) && FINITE_RNK(p->vecsz->rnk)

       /* FIXME: multidimensional R2HCII ? */

       && (p->kind == R2HC || p->kind == HC2R)

       && p->sz->rnk >= 2

       && picksplit(ego, p->sz, rp)

       && (0

     /* can work out-of-place, but HC2R destroys input */

     || (p->r0 != p->cr && 

         (p->kind == R2HC || !NO_DESTROY_INPUTP(plnr)))

     /* FIXME: what are sufficient conditions for inplace? */

     || (p->r0 == p->cr))

    );

}

/* TODO: revise this. */

static int applicable(const solver *ego_, const problem *p_, 

          const planner *plnr, int *rp)

{

     const S *ego = (const S *)ego_;

     if (!applicable0(ego_, p_, rp, plnr)) return 0;

     if (NO_RANK_SPLITSP(plnr) && (ego->spltrnk != ego->buddies[0]))

          return 0;

     if (NO_UGLYP(plnr)) {

    const problem_rdft2 *p = (const problem_rdft2 *) p_;

    /* Heuristic: if the vector stride is greater than the transform

       size, don't use (prefer to do the vector loop first with a

       vrank-geq1 plan). */

    if (p->vecsz->rnk > 0 &&

        X(tensor_min_stride)(p->vecsz) 

        > X(rdft2_tensor_max_index)(p->sz, p->kind))

         return 0;

     }

     return 1;

}

static plan *mkplan(const solver *ego_, const problem *p_, planner *plnr)

{

     const S *ego = (const S *) ego_;

     const problem_rdft2 *p;

     P *pln;

     plan *cldr = 0, *cldc = 0;

     tensor *sz1, *sz2, *vecszi, *sz2i;

     int spltrnk;

     inplace_kind k;

     problem *cldp;

     static const plan_adt padt = {

    X(rdft2_solve), awake, print, destroy

     };

     if (!applicable(ego_, p_, plnr, &spltrnk))

          return (plan *) 0;

     p = (const problem_rdft2 *) p_;

     X(tensor_split)(p->sz, &sz1, spltrnk, &sz2);

     k = p->kind == R2HC ? INPLACE_OS : INPLACE_IS;

     vecszi = X(tensor_copy_inplace)(p->vecsz, k);

     sz2i = X(tensor_copy_inplace)(sz2, k);

     /* complex data is ~half of real */

     sz2i->dims[sz2i->rnk - 1].n = sz2i->dims[sz2i->rnk - 1].n/2 + 1;

     cldr = X(mkplan_d)(plnr, 

           X(mkproblem_rdft2_d)(X(tensor_copy)(sz2),

              X(tensor_append)(p->vecsz, sz1),

              p->r0, p->r1,

              p->cr, p->ci, p->kind));

     if (!cldr) goto nada;

     if (p->kind == R2HC)

    cldp = X(mkproblem_dft_d)(X(tensor_copy_inplace)(sz1, k),

            X(tensor_append)(vecszi, sz2i),

            p->cr, p->ci, p->cr, p->ci);

     else /* HC2R must swap re/im parts to get IDFT */

    cldp = X(mkproblem_dft_d)(X(tensor_copy_inplace)(sz1, k),

            X(tensor_append)(vecszi, sz2i),

            p->ci, p->cr, p->ci, p->cr);

     cldc = X(mkplan_d)(plnr, cldp);

     if (!cldc) goto nada;

     pln = MKPLAN_RDFT2(P, &padt, p->kind == R2HC ? apply_r2hc : apply_hc2r);

     pln->cldr = cldr;

     pln->cldc = cldc;

     pln->solver = ego;

     X(ops_add)(&cldr->ops, &cldc->ops, &pln->super.super.ops);

     X(tensor_destroy4)(sz2i, vecszi, sz2, sz1);

     return &(pln->super.super);

 nada:

     X(plan_destroy_internal)(cldr);

     X(plan_destroy_internal)(cldc);

     X(tensor_destroy4)(sz2i, vecszi, sz2, sz1);

     return (plan *) 0;

}

static solver *mksolver(int spltrnk, const int *buddies, size_t nbuddies)

{

     static const solver_adt sadt = { PROBLEM_RDFT2, mkplan, 0 };

     S *slv = MKSOLVER(S, &sadt);

     slv->spltrnk = spltrnk;

     slv->buddies = buddies;

     slv->nbuddies = nbuddies;

     return &(slv->super);

}

void X(rdft2_rank_geq2_register)(planner *p)

{

     static const int buddies[] = { 1, 0, -2 };

     size_t i;

     for (i = 0; i < NELEM(buddies); ++i)

          REGISTER_SOLVER(p, mksolver(buddies[i], buddies, NELEM(buddies)));

     /* FIXME: Should we try more buddies?  See also dft/rank-geq2. */

}