/*

 * 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 ct_solver S;

typedef struct {

     plan_dftw super;

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

     plan *cld;

     twid *td;

     const S *slv;

     int dec;

} P;

static void mktwiddle(P *ego, enum wakefulness wakefulness)

{

     static const tw_instr tw[] = { { TW_FULL, 0, 0 }, { TW_NEXT, 1, 0 } };

     /* note that R and M are swapped, to allow for sequential

  access both to data and twiddles */

     X(twiddle_awake)(wakefulness, &ego->td, tw,

          ego->r * ego->m, ego->m, ego->r);

}

static void bytwiddle(const P *ego, R *rio, R *iio)

{

     INT iv, ir, im;

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

     INT m = ego->m, mb = ego->mb, me = ego->me, ms = ego->ms;

     INT v = ego->v, vs = ego->vs;

     const R *W = ego->td->W;

     mb += (mb == 0); /* skip m=0 iteration */

     for (iv = 0; iv < v; ++iv) {

    for (ir = 1; ir < r; ++ir) {

         for (im = mb; im < me; ++im) {

        R *pr = rio + ms * im + rs * ir;

        R *pi = iio + ms * im + rs * ir;

        E xr = *pr;

        E xi = *pi;

        E wr = W[2 * im + (2 * (m-1)) * ir - 2];

        E wi = W[2 * im + (2 * (m-1)) * ir - 1];

        *pr = xr * wr + xi * wi;

        *pi = xi * wr - xr * wi;

         }

    }

    rio += vs;

    iio += vs;

     }

}

static int applicable(INT irs, INT ors, INT ivs, INT ovs,

          const planner *plnr)

{

     return (1

       && irs == ors

       && ivs == ovs

       && !NO_SLOWP(plnr)

    );

}

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

{

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

     plan_dft *cld;

     INT dm = ego->ms * ego->mb;

     bytwiddle(ego, rio, iio);

     cld = (plan_dft *) ego->cld;

     cld->apply(ego->cld, rio + dm, iio + dm, rio + dm, iio + dm);

}

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

{

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

     plan_dft *cld;

     INT dm = ego->ms * ego->mb;

     cld = (plan_dft *) ego->cld;

     cld->apply(ego->cld, rio + dm, iio + dm, rio + dm, iio + dm);

     bytwiddle(ego, rio, iio);

}

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

{

     P *ego = (P *) ego_;

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

     mktwiddle(ego, wakefulness);

}

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-generic-%s-%D-%D%v%(%p%))",

        ego->dec == DECDIT ? "dit" : "dif",

        ego->r, ego->m, ego->v, 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;

     INT dm = ms * mstart;

     static const plan_adt padt = {

    0, awake, print, destroy

     };

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

     if (!applicable(irs, ors, ivs, ovs, plnr))

          return (plan *)0;

     cld = X(mkplan_d)(plnr,

      X(mkproblem_dft_d)(

           X(mktensor_1d)(r, irs, irs),

           X(mktensor_2d)(mcount, ms, ms, v, ivs, ivs),

           rio + dm, iio + dm, rio + dm, iio + dm)

      );

     if (!cld) goto nada;

     pln = MKPLAN_DFTW(P, &padt, ego->dec == DECDIT ? apply_dit : apply_dif);

     pln->slv = ego;

     pln->cld = cld;

     pln->r = r;

     pln->rs = irs;

     pln->m = m;

     pln->ms = ms;

     pln->v = v;

     pln->vs = ivs;

     pln->mb = mstart;

     pln->me = mstart + mcount;

     pln->dec = ego->dec;

     pln->td = 0;

     {

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

    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 dec)

{

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

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

     if (X(mksolver_ct_hook)) {

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

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

     }

}

void X(ct_generic_register)(planner *p)

{

     regsolver(p, 0, DECDIT);

     regsolver(p, 0, DECDIF);

}