/*

 * 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

 *

 */

#include "rdft/rdft.h"

typedef struct {

     solver super;

} S;

typedef struct {

     plan_rdft2 super;

     plan *cld, *cldrest;

     INT n, vl, nbuf, bufdist;

     INT cs, ivs, ovs;

} P;

/***************************************************************************/

/* FIXME: have alternate copy functions that push a vector loop inside

   the n loops? */

/* copy halfcomplex array r (contiguous) to complex (strided) array rio/iio. */

static void hc2c(INT n, R *r, R *rio, R *iio, INT os)

{

     INT i;

     rio[0] = r[0];

     iio[0] = 0;

     for (i = 1; i + i < n; ++i) {

    rio[i * os] = r[i];

    iio[i * os] = r[n - i];

     }

     if (i + i == n) { /* store the Nyquist frequency */

    rio[i * os] = r[i];

    iio[i * os] = K(0.0);

     }

}

/* reverse of hc2c */

static void c2hc(INT n, R *rio, R *iio, INT is, R *r)

{

     INT i;

     r[0] = rio[0];

     for (i = 1; i + i < n; ++i) {

    r[i] = rio[i * is];

    r[n - i] = iio[i * is];

     }

     if (i + i == n)   /* store the Nyquist frequency */

    r[i] = rio[i * is];

}

/***************************************************************************/

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

{

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

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

     INT i, j, vl = ego->vl, nbuf = ego->nbuf, bufdist = ego->bufdist;

     INT n = ego->n;

     INT ivs = ego->ivs, ovs = ego->ovs, os = ego->cs;

     R *bufs = (R *)MALLOC(sizeof(R) * nbuf * bufdist, BUFFERS);

     plan_rdft2 *cldrest;

     for (i = nbuf; i <= vl; i += nbuf) {

          /* transform to bufs: */

          cld->apply((plan *) cld, r0, bufs);

    r0 += ivs * nbuf; r1 += ivs * nbuf;

          /* copy back */

    for (j = 0; j < nbuf; ++j, cr += ovs, ci += ovs)

         hc2c(n, bufs + j*bufdist, cr, ci, os);

     }

     X(ifree)(bufs);

     /* Do the remaining transforms, if any: */

     cldrest = (plan_rdft2 *) ego->cldrest;

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

}

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

{

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

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

     INT i, j, vl = ego->vl, nbuf = ego->nbuf, bufdist = ego->bufdist;

     INT n = ego->n;

     INT ivs = ego->ivs, ovs = ego->ovs, is = ego->cs;

     R *bufs = (R *)MALLOC(sizeof(R) * nbuf * bufdist, BUFFERS);

     plan_rdft2 *cldrest;

     for (i = nbuf; i <= vl; i += nbuf) {

          /* copy to bufs */

    for (j = 0; j < nbuf; ++j, cr += ivs, ci += ivs)

         c2hc(n, cr, ci, is, bufs + j*bufdist);

          /* transform back: */

          cld->apply((plan *) cld, bufs, r0);

    r0 += ovs * nbuf; r1 += ovs * nbuf;

     }

     X(ifree)(bufs);

     /* Do the remaining transforms, if any: */

     cldrest = (plan_rdft2 *) ego->cldrest;

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

}

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

{

     P *ego = (P *) ego_;

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

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

}

static void destroy(plan *ego_)

{

     P *ego = (P *) ego_;

     X(plan_destroy_internal)(ego->cldrest);

     X(plan_destroy_internal)(ego->cld);

}

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

{

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

     p->print(p, "(rdft2-rdft-%s-%D%v/%D-%D%(%p%)%(%p%))",

        ego->super.apply == apply_r2hc ? "r2hc" : "hc2r",

              ego->n, ego->nbuf,

              ego->vl, ego->bufdist % ego->n,

              ego->cld, ego->cldrest);

}

static INT min_nbuf(const problem_rdft2 *p, INT n, INT vl)

{

     INT is, os, ivs, ovs;

     if (p->r0 != p->cr)

    return 1;

     if (X(rdft2_inplace_strides(p, RNK_MINFTY)))

    return 1;

     A(p->vecsz->rnk == 1); /*  rank 0 and MINFTY are inplace */

     X(rdft2_strides)(p->kind, p->sz->dims, &is, &os);

     X(rdft2_strides)(p->kind, p->vecsz->dims, &ivs, &ovs);

     /* handle one potentially common case: "contiguous" real and

  complex arrays, which overlap because of the differing sizes. */

     if (n * X(iabs)(is) <= X(iabs)(ivs)

   && (n/2 + 1) * X(iabs)(os) <= X(iabs)(ovs)

   && ( ((p->cr - p->ci) <= X(iabs)(os)) || 

        ((p->ci - p->cr) <= X(iabs)(os)) )

   && ivs > 0 && ovs > 0) {

    INT vsmin = X(imin)(ivs, ovs);

    INT vsmax = X(imax)(ivs, ovs);

    return(((vsmax - vsmin) * vl + vsmin - 1) / vsmin);

     }

     return vl; /* punt: just buffer the whole vector */

}

static int applicable0(const problem *p_, const S *ego, const planner *plnr)

{

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

     UNUSED(ego);

     return(1

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

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

      /* FIXME: does it make sense to do R2HCII ? */

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

      /* real strides must allow for reduction to rdft */

      && (2 * (p->r1 - p->r0) ==

    (((p->kind == R2HC) ? p->sz->dims[0].is : p->sz->dims[0].os)))

      && !(X(toobig)(p->sz->dims[0].n) && CONSERVE_MEMORYP(plnr))

    );

}

static int applicable(const problem *p_, const S *ego, const planner *plnr)

{

     const problem_rdft2 *p;

     if (NO_BUFFERINGP(plnr)) return 0;

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

     p = (const problem_rdft2 *) p_;

     if (NO_UGLYP(plnr)) {

    if (p->r0 != p->cr) return 0;

    if (X(toobig)(p->sz->dims[0].n)) return 0;

     }

     return 1;

}

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

{

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

     P *pln;

     plan *cld = (plan *) 0;

     plan *cldrest = (plan *) 0;

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

     R *bufs = (R *) 0;

     INT nbuf = 0, bufdist, n, vl;

     INT ivs, ovs, rs, id, od;

     static const plan_adt padt = {

    X(rdft2_solve), awake, print, destroy

     };

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

          goto nada;

     n = p->sz->dims[0].n;

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

     nbuf = X(imax)(X(nbuf)(n, vl, 0), min_nbuf(p, n, vl));

     bufdist = X(bufdist)(n, vl);

     A(nbuf > 0);

     /* initial allocation for the purpose of planning */

     bufs = (R *) MALLOC(sizeof(R) * nbuf * bufdist, BUFFERS);

     id = ivs * (nbuf * (vl / nbuf));

     od = ovs * (nbuf * (vl / nbuf));

     if (p->kind == R2HC) {

    cld = X(mkplan_f_d)(

         plnr,

         X(mkproblem_rdft_d)(

        X(mktensor_1d)(n, p->sz->dims[0].is/2, 1),

        X(mktensor_1d)(nbuf, ivs, bufdist),

        TAINT(p->r0, ivs * nbuf), bufs, &p->kind),

         0, 0, (p->r0 == p->cr) ? NO_DESTROY_INPUT : 0);

    if (!cld) goto nada;

    X(ifree)(bufs); bufs = 0;

    cldrest = X(mkplan_d)(plnr, 

        X(mkproblem_rdft2_d)(

             X(tensor_copy)(p->sz),

             X(mktensor_1d)(vl % nbuf, ivs, ovs),

             p->r0 + id, p->r1 + id, 

             p->cr + od, p->ci + od,

             p->kind));

    if (!cldrest) goto nada;

    pln = MKPLAN_RDFT2(P, &padt, apply_r2hc);

     } else {

    A(p->kind == HC2R);

    cld = X(mkplan_f_d)(

         plnr,

         X(mkproblem_rdft_d)(

        X(mktensor_1d)(n, 1, p->sz->dims[0].os/2),

        X(mktensor_1d)(nbuf, bufdist, ovs),

        bufs, TAINT(p->r0, ovs * nbuf), &p->kind),

         0, 0, NO_DESTROY_INPUT); /* always ok to destroy bufs */

    if (!cld) goto nada;

    X(ifree)(bufs); bufs = 0;

    cldrest = X(mkplan_d)(plnr, 

        X(mkproblem_rdft2_d)(

             X(tensor_copy)(p->sz),

             X(mktensor_1d)(vl % nbuf, ivs, ovs),

             p->r0 + od, p->r1 + od, 

             p->cr + id, p->ci + id,

             p->kind));

    if (!cldrest) goto nada;

    pln = MKPLAN_RDFT2(P, &padt, apply_hc2r);

     }

     pln->cld = cld;

     pln->cldrest = cldrest;

     pln->n = n;

     pln->vl = vl;

     pln->ivs = ivs;

     pln->ovs = ovs;

     X(rdft2_strides)(p->kind, &p->sz->dims[0], &rs, &pln->cs);

     pln->nbuf = nbuf;

     pln->bufdist = bufdist;

     X(ops_madd)(vl / nbuf, &cld->ops, &cldrest->ops,

     &pln->super.super.ops);

     pln->super.super.ops.other += (p->kind == R2HC ? (n + 2) : n) * vl;

     return &(pln->super.super);

 nada:

     X(ifree0)(bufs);

     X(plan_destroy_internal)(cldrest);

     X(plan_destroy_internal)(cld);

     return (plan *) 0;

}

static solver *mksolver(void)

{

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

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

     return &(slv->super);

}

void X(rdft2_rdft_register)(planner *p)

{

     REGISTER_SOLVER(p, mksolver());

}