/*

 * 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

 *

 */

/* solvers/plans for vectors of small DFT's that cannot be done

   in-place directly.  Use a rank-0 plan to rearrange the data

   before or after the transform.  Can also change an out-of-place

   plan into a copy + in-place (where the in-place transform

   is e.g. unit stride). */

/* FIXME: merge with rank-geq2.c(?), since this is just a special case

   of a rank split where the first/second transform has rank 0. */

#include "dft/dft.h"

typedef problem *(*mkcld_t) (const problem_dft *p);

typedef struct {

     dftapply apply;

     problem *(*mkcld)(const problem_dft *p);

     const char *nam;

} ndrct_adt;

typedef struct {

     solver super;

     const ndrct_adt *adt;

} S;

typedef struct {

     plan_dft super;

     plan *cldcpy, *cld;

     const S *slv;

} P;

/*-----------------------------------------------------------------------*/

/* first rearrange, then transform */

static void apply_before(const plan *ego_, R *ri, R *ii, R *ro, R *io)

{

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

     {

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

          cldcpy->apply(ego->cldcpy, ri, ii, ro, io);

     }

     {

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

          cld->apply(ego->cld, ro, io, ro, io);

     }

}

static problem *mkcld_before(const problem_dft *p)

{

     return X(mkproblem_dft_d)(X(tensor_copy_inplace)(p->sz, INPLACE_OS),

             X(tensor_copy_inplace)(p->vecsz, INPLACE_OS),

             p->ro, p->io, p->ro, p->io);

}

static const ndrct_adt adt_before =

{

     apply_before, mkcld_before, "dft-indirect-before"

};

/*-----------------------------------------------------------------------*/

/* first transform, then rearrange */

static void apply_after(const plan *ego_, R *ri, R *ii, R *ro, R *io)

{

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

     {

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

          cld->apply(ego->cld, ri, ii, ri, ii);

     }

     {

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

          cldcpy->apply(ego->cldcpy, ri, ii, ro, io);

     }

}

static problem *mkcld_after(const problem_dft *p)

{

     return X(mkproblem_dft_d)(X(tensor_copy_inplace)(p->sz, INPLACE_IS),

             X(tensor_copy_inplace)(p->vecsz, INPLACE_IS),

             p->ri, p->ii, p->ri, p->ii);

}

static const ndrct_adt adt_after =

{

     apply_after, mkcld_after, "dft-indirect-after"

};

/*-----------------------------------------------------------------------*/

static void destroy(plan *ego_)

{

     P *ego = (P *) ego_;

     X(plan_destroy_internal)(ego->cld);

     X(plan_destroy_internal)(ego->cldcpy);

}

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

{

     P *ego = (P *) ego_;

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

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

}

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

{

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

     const S *s = ego->slv;

     p->print(p, "(%s%(%p%)%(%p%))", s->adt->nam, ego->cld, ego->cldcpy);

}

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

           const planner *plnr)

{

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

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

     return (1

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

       /* problem must be a nontrivial transform, not just a copy */

       && p->sz->rnk > 0

       && (0

     /* problem must be in-place & require some

        rearrangement of the data; to prevent

        infinite loops with indirect-transpose, we

        further require that at least some transform

        strides must decrease */

     || (p->ri == p->ro

         && !X(tensor_inplace_strides2)(p->sz, p->vecsz)

         && X(tensor_strides_decrease)(

        p->sz, p->vecsz,

        ego->adt->apply == apply_after ? 

        INPLACE_IS : INPLACE_OS))

     /* or problem must be out of place, transforming

        from stride 1/2 to bigger stride, for apply_after */

     || (p->ri != p->ro && ego->adt->apply == apply_after

         && !NO_DESTROY_INPUTP(plnr)

         && X(tensor_min_istride)(p->sz) <= 2

         && X(tensor_min_ostride)(p->sz) > 2)

     /* or problem must be out of place, transforming

        to stride 1/2 from bigger stride, for apply_before */

     || (p->ri != p->ro && ego->adt->apply == apply_before

         && X(tensor_min_ostride)(p->sz) <= 2

         && X(tensor_min_istride)(p->sz) > 2)

      )

    );

}

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

          const planner *plnr)

{

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

     {

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

    if (NO_INDIRECT_OP_P(plnr) && p->ri != p->ro) return 0;

     }

     return 1;

}

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

{

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

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

     P *pln;

     plan *cld = 0, *cldcpy = 0;

     static const plan_adt padt = {

    X(dft_solve), awake, print, destroy

     };

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

          return (plan *) 0;

     cldcpy =

    X(mkplan_d)(plnr, 

          X(mkproblem_dft_d)(X(mktensor_0d)(),

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

           p->ri, p->ii, p->ro, p->io));

     if (!cldcpy) goto nada;

     cld = X(mkplan_f_d)(plnr, ego->adt->mkcld(p), NO_BUFFERING, 0, 0);

     if (!cld) goto nada;

     pln = MKPLAN_DFT(P, &padt, ego->adt->apply);

     pln->cld = cld;

     pln->cldcpy = cldcpy;

     pln->slv = ego;

     X(ops_add)(&cld->ops, &cldcpy->ops, &pln->super.super.ops);

     return &(pln->super.super);

 nada:

     X(plan_destroy_internal)(cld);

     X(plan_destroy_internal)(cldcpy);

     return (plan *)0;

}

static solver *mksolver(const ndrct_adt *adt)

{

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

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

     slv->adt = adt;

     return &(slv->super);

}

void X(dft_indirect_register)(planner *p)

{

     unsigned i;

     static const ndrct_adt *const adts[] = {

    &adt_before, &adt_after

     };

     for (i = 0; i < sizeof(adts) / sizeof(adts[0]); ++i)

          REGISTER_SOLVER(p, mksolver(adts[i]));

}