/*

 * 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

 *

 */

/* express a twiddle problem in terms of dft + multiplication by

   twiddle factors */

#include "dft/ct.h"

typedef struct {

     ct_solver super;

     INT batchsz;

} S;

typedef struct {

     plan_dftw super;

     INT r, rs, m, ms, v, vs, mb, me;

     INT batchsz;

     plan *cld;

     triggen *t;

     const S *slv;

} P;

#define BATCHDIST(r) ((r) + 16)

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

static void bytwiddle(const P *ego, INT mb, INT me, R *buf, R *rio, R *iio)

{

     INT j, k;

     INT r = ego->r, rs = ego->rs, ms = ego->ms;

     triggen *t = ego->t;

     for (j = 0; j < r; ++j) {

    for (k = mb; k < me; ++k)

         t->rotate(t, j * k,

       rio[j * rs + k * ms],

       iio[j * rs + k * ms],

       &buf[j * 2 + 2 * BATCHDIST(r) * (k - mb) + 0]);

     }

}

static int applicable0(const S *ego,

           INT r, INT irs, INT ors,

           INT m, INT v,

           INT mcount)

{

     return (1

       && v == 1

       && irs == ors

       && mcount >= ego->batchsz

       && mcount % ego->batchsz == 0

       && r >= 64 

       && m >= r

    );

}

static int applicable(const S *ego,

          INT r, INT irs, INT ors,

          INT m, INT v,

          INT mcount,

          const planner *plnr)

{

     if (!applicable0(ego, r, irs, ors, m, v, mcount))

    return 0;

     if (NO_UGLYP(plnr) && m * r < 65536)

    return 0;

     return 1;

}

static void dobatch(const P *ego, INT mb, INT me, R *buf, R *rio, R *iio)

{

     plan_dft *cld;

     INT ms = ego->ms;

     bytwiddle(ego, mb, me, buf, rio, iio);

     cld = (plan_dft *) ego->cld;

     cld->apply(ego->cld, buf, buf + 1, buf, buf + 1);

     X(cpy2d_pair_co)(buf, buf + 1,

          rio + ms * mb, iio + ms * mb,

          me-mb, 2 * BATCHDIST(ego->r), ms,

          ego->r, 2, ego->rs);

}

static void apply(const plan *ego_, R *rio, R *iio)

{

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

     R *buf = (R *) MALLOC(sizeof(R) * 2 * BATCHDIST(ego->r) * ego->batchsz,

         BUFFERS);

     INT m;

     for (m = ego->mb; m < ego->me; m += ego->batchsz)

    dobatch(ego, m, m + ego->batchsz, buf, rio, iio);

     A(m == ego->me);

     X(ifree)(buf);

}

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

{

     P *ego = (P *) ego_;

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

     switch (wakefulness) {

   case SLEEPY:

        X(triggen_destroy)(ego->t); ego->t = 0;

        break;

   default:

        ego->t = X(mktriggen)(AWAKE_SQRTN_TABLE, ego->r * ego->m);

        break;

     }

}

static void destroy(plan *ego_)

{

     P *ego = (P *) ego_;

     X(plan_destroy_internal)(ego->cld);

}

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

{

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

     p->print(p, "(dftw-genericbuf/%D-%D-%D%(%p%))",

        ego->batchsz, ego->r, ego->m, ego->cld);

}

static plan *mkcldw(const ct_solver *ego_,

        INT r, INT irs, INT ors,

        INT m, INT ms,

        INT v, INT ivs, INT ovs,

        INT mstart, INT mcount,

        R *rio, R *iio,

        planner *plnr)

{

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

     P *pln;

     plan *cld = 0;

     R *buf;

     static const plan_adt padt = {

    0, awake, print, destroy

     };

     UNUSED(ivs); UNUSED(ovs); UNUSED(rio); UNUSED(iio);

     A(mstart >= 0 && mstart + mcount <= m);

     if (!applicable(ego, r, irs, ors, m, v, mcount, plnr))

          return (plan *)0;

     buf = (R *) MALLOC(sizeof(R) * 2 * BATCHDIST(r) * ego->batchsz, BUFFERS);

     cld = X(mkplan_d)(plnr,

      X(mkproblem_dft_d)(

           X(mktensor_1d)(r, 2, 2),

           X(mktensor_1d)(ego->batchsz,

              2 * BATCHDIST(r),

              2 * BATCHDIST(r)),

           buf, buf + 1, buf, buf + 1

           )

      );

     X(ifree)(buf);

     if (!cld) goto nada;

     pln = MKPLAN_DFTW(P, &padt, apply);

     pln->slv = ego;

     pln->cld = cld;

     pln->r = r;

     pln->m = m;

     pln->ms = ms;

     pln->rs = irs;

     pln->batchsz = ego->batchsz;

     pln->mb = mstart;

     pln->me = mstart + mcount;

     {

    double n0 = (r - 1) * (mcount - 1);

    pln->super.super.ops = cld->ops;

    pln->super.super.ops.mul += 8 * n0;

    pln->super.super.ops.add += 4 * n0;

    pln->super.super.ops.other += 8 * n0;

     }

     return &(pln->super.super);

 nada:

     X(plan_destroy_internal)(cld);

     return (plan *) 0;

}

static void regsolver(planner *plnr, INT r, INT batchsz)

{

     S *slv = (S *)X(mksolver_ct)(sizeof(S), r, DECDIT, mkcldw, 0);

     slv->batchsz = batchsz;

     REGISTER_SOLVER(plnr, &(slv->super.super));

     if (X(mksolver_ct_hook)) {

    slv = (S *)X(mksolver_ct_hook)(sizeof(S), r, DECDIT, mkcldw, 0);

    slv->batchsz = batchsz;

    REGISTER_SOLVER(plnr, &(slv->super.super));

     }

}

void X(ct_genericbuf_register)(planner *p)

{

     static const INT radices[] = { -1, -2, -4, -8, -16, -32, -64 };

     static const INT batchsizes[] = { 4, 8, 16, 32, 64 };

     unsigned i, j;

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

    for (j = 0; j < sizeof(batchsizes) / sizeof(batchsizes[0]); ++j)

         regsolver(p, radices[i], batchsizes[j]);

}