/*

 * 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

 *

 */

/* direct DFT solver, if we have a codelet */

#include "dft/dft.h"

typedef struct {

     solver super;

     const kdft_desc *desc;

     kdft k;

     int bufferedp;

} S;

typedef struct {

     plan_dft super;

     stride is, os, bufstride;

     INT n, vl, ivs, ovs;

     kdft k;

     const S *slv;

} P;

static void dobatch(const P *ego, R *ri, R *ii, R *ro, R *io, 

        R *buf, INT batchsz)

{

     X(cpy2d_pair_ci)(ri, ii, buf, buf+1,

          ego->n, WS(ego->is, 1), WS(ego->bufstride, 1),

          batchsz, ego->ivs, 2);

     if (IABS(WS(ego->os, 1)) < IABS(ego->ovs)) {

    /* transform directly to output */

    ego->k(buf, buf+1, ro, io, 

     ego->bufstride, ego->os, batchsz, 2, ego->ovs);

     } else {

    /* transform to buffer and copy back */

    ego->k(buf, buf+1, buf, buf+1, 

     ego->bufstride, ego->bufstride, batchsz, 2, 2);

    X(cpy2d_pair_co)(buf, buf+1, ro, io,

         ego->n, WS(ego->bufstride, 1), WS(ego->os, 1), 

         batchsz, 2, ego->ovs);

     }

}

static INT compute_batchsize(INT n)

{

     /* round up to multiple of 4 */

     n += 3;

     n &= -4;

     return (n + 2);

}

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

{

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

     R *buf;

     INT vl = ego->vl, n = ego->n, batchsz = compute_batchsize(n);

     INT i;

     size_t bufsz = n * batchsz * 2 * sizeof(R);

     BUF_ALLOC(R *, buf, bufsz);

     for (i = 0; i < vl - batchsz; i += batchsz) {

    dobatch(ego, ri, ii, ro, io, buf, batchsz);

    ri += batchsz * ego->ivs; ii += batchsz * ego->ivs;

    ro += batchsz * ego->ovs; io += batchsz * ego->ovs;

     }

     dobatch(ego, ri, ii, ro, io, buf, vl - i);

     BUF_FREE(buf, bufsz);

}

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

{

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

     ASSERT_ALIGNED_DOUBLE;

     ego->k(ri, ii, ro, io, ego->is, ego->os, ego->vl, ego->ivs, ego->ovs);

}

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

{

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

     INT vl = ego->vl;

     ASSERT_ALIGNED_DOUBLE;

     /* for 4-way SIMD when VL is odd: iterate over an

  even vector length VL, and then execute the last

  iteration as a 2-vector with vector stride 0. */

     ego->k(ri, ii, ro, io, ego->is, ego->os, vl - 1, ego->ivs, ego->ovs);

     ego->k(ri + (vl - 1) * ego->ivs, ii + (vl - 1) * ego->ivs,

      ro + (vl - 1) * ego->ovs, io + (vl - 1) * ego->ovs,

      ego->is, ego->os, 1, 0, 0);

}

static void destroy(plan *ego_)

{

     P *ego = (P *) ego_;

     X(stride_destroy)(ego->is);

     X(stride_destroy)(ego->os);

     X(stride_destroy)(ego->bufstride);

}

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

{

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

     const S *s = ego->slv;

     const kdft_desc *d = s->desc;

     if (ego->slv->bufferedp)

    p->print(p, "(dft-directbuf/%D-%D%v \"%s\")", 

       compute_batchsize(d->sz), d->sz, ego->vl, d->nam);

     else

    p->print(p, "(dft-direct-%D%v \"%s\")", d->sz, ego->vl, d->nam);

}

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

        const planner *plnr)

{

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

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

     const kdft_desc *d = ego->desc;

     INT vl;

     INT ivs, ovs;

     INT batchsz;

     return (

    1

    && p->sz->rnk == 1

    && p->vecsz->rnk == 1

    && p->sz->dims[0].n == d->sz

    /* check strides etc */

    && X(tensor_tornk1)(p->vecsz, &vl, &ivs, &ovs)

    /* UGLY if IS <= IVS */

    && !(NO_UGLYP(plnr) &&

         X(iabs)(p->sz->dims[0].is) <= X(iabs)(ivs))

    && (batchsz = compute_batchsize(d->sz), 1)

    && (d->genus->okp(d, 0, ((const R *)0) + 1, p->ro, p->io,

          2 * batchsz, p->sz->dims[0].os,

          batchsz, 2, ovs, plnr))

    && (d->genus->okp(d, 0, ((const R *)0) + 1, p->ro, p->io,

          2 * batchsz, p->sz->dims[0].os,

          vl % batchsz, 2, ovs, plnr))

    && (0

        /* can operate out-of-place */

        || p->ri != p->ro

        /* can operate in-place as long as strides are the same */

        || X(tensor_inplace_strides2)(p->sz, p->vecsz)

        /* can do it if the problem fits in the buffer, no matter

     what the strides are */

        || vl <= batchsz

         )

    );

}

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

          const planner *plnr, int *extra_iterp)

{

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

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

     const kdft_desc *d = ego->desc;

     INT vl;

     INT ivs, ovs;

     return (

    1

    && p->sz->rnk == 1

    && p->vecsz->rnk <= 1

    && p->sz->dims[0].n == d->sz

    /* check strides etc */

    && X(tensor_tornk1)(p->vecsz, &vl, &ivs, &ovs)

    && ((*extra_iterp = 0,

         (d->genus->okp(d, p->ri, p->ii, p->ro, p->io,

            p->sz->dims[0].is, p->sz->dims[0].os,

            vl, ivs, ovs, plnr)))

        ||

        (*extra_iterp = 1,

         ((d->genus->okp(d, p->ri, p->ii, p->ro, p->io,

             p->sz->dims[0].is, p->sz->dims[0].os,

             vl - 1, ivs, ovs, plnr))

    &&

    (d->genus->okp(d, p->ri, p->ii, p->ro, p->io,

             p->sz->dims[0].is, p->sz->dims[0].os,

             2, 0, 0, plnr)))))

    && (0

        /* can operate out-of-place */

        || p->ri != p->ro

        /* can always compute one transform */

        || vl == 1

        /* can operate in-place as long as strides are the same */

        || X(tensor_inplace_strides2)(p->sz, p->vecsz)

         )

    );

}

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

{

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

     P *pln;

     const problem_dft *p;

     iodim *d;

     const kdft_desc *e = ego->desc;

     static const plan_adt padt = {

    X(dft_solve), X(null_awake), print, destroy

     };

     UNUSED(plnr);

     if (ego->bufferedp) {

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

         return (plan *)0;

    pln = MKPLAN_DFT(P, &padt, apply_buf);

     } else {

    int extra_iterp = 0;

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

         return (plan *)0;

    pln = MKPLAN_DFT(P, &padt, extra_iterp ? apply_extra_iter : apply);

     }

     p = (const problem_dft *) p_;

     d = p->sz->dims;

     pln->k = ego->k;

     pln->n = d[0].n;

     pln->is = X(mkstride)(pln->n, d[0].is);

     pln->os = X(mkstride)(pln->n, d[0].os);

     pln->bufstride = X(mkstride)(pln->n, 2 * compute_batchsize(pln->n));

     X(tensor_tornk1)(p->vecsz, &pln->vl, &pln->ivs, &pln->ovs);

     pln->slv = ego;

     X(ops_zero)(&pln->super.super.ops);

     X(ops_madd2)(pln->vl / e->genus->vl, &e->ops, &pln->super.super.ops);

     if (ego->bufferedp) 

    pln->super.super.ops.other += 4 * pln->n * pln->vl;

     pln->super.super.could_prune_now_p = !ego->bufferedp;

     return &(pln->super.super);

}

static solver *mksolver(kdft k, const kdft_desc *desc, int bufferedp)

{

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

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

     slv->k = k;

     slv->desc = desc;

     slv->bufferedp = bufferedp;

     return &(slv->super);

}

solver *X(mksolver_dft_direct)(kdft k, const kdft_desc *desc)

{

     return mksolver(k, desc, 0);

}

solver *X(mksolver_dft_directbuf)(kdft k, const kdft_desc *desc)

{

     return mksolver(k, desc, 1);

}