/*

 * 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 hc2hc problem in terms of rdft + multiplication by

   twiddle factors */

#include "rdft/hc2hc.h"

typedef hc2hc_solver S;

typedef struct {

     plan_hc2hc super;

     INT r, m, s, vl, vs, mstart1, mcount1;

     plan *cld0;

     plan *cld;

     twid *td;

} P;

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

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

{

     static const tw_instr tw[] = { { TW_HALF, 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 *IO, R sign)

{

     INT i, j, k;

     INT r = ego->r, m = ego->m, s = ego->s, vl = ego->vl, vs = ego->vs;

     INT ms = m * s;

     INT mstart1 = ego->mstart1, mcount1 = ego->mcount1;

     INT wrem = 2 * ((m-1)/2 - mcount1);

     for (i = 0; i < vl; ++i, IO += vs) {

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

    A(m % 2 == 1);

    for (k = 1, W += (m - 1) + 2*(mstart1-1); k < r; ++k) {

         /* pr := IO + (j + mstart1) * s + k * ms */

         R *pr = IO + mstart1 * s + k * ms;

         /* pi := IO + (m - j - mstart1) * s + k * ms */

         R *pi = IO - mstart1 * s + (k + 1) * ms;

         for (j = 0; j < mcount1; ++j, pr += s, pi -= s) {

        E xr = *pr;

        E xi = *pi;

        E wr = W[0];

        E wi = sign * W[1];

        *pr = xr * wr - xi * wi;

        *pi = xi * wr + xr * wi;

        W += 2;

         }

         W += wrem;

    }

     }

}

static void swapri(R *IO, INT r, INT m, INT s, INT jstart, INT jend)

{

     INT k;

     INT ms = m * s;

     INT js = jstart * s;

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

    /* pr := IO + (m - j) * s + k * ms */

    R *pr = IO + (k + 1) * ms - js;

    /* pi := IO + (m - j) * s + (r - 1 - k) * ms */

    R *pi = IO + (r - k) * ms - js;

    INT j;

    for (j = jstart; j < jend; j += 1, pr -= s, pi -= s) {

         R t = *pr;

         *pr = *pi;

         *pi = t;

    }

     }

}

static void reorder_dit(const P *ego, R *IO)

{

     INT i, k;

     INT r = ego->r, m = ego->m, s = ego->s, vl = ego->vl, vs = ego->vs;

     INT ms = m * s;

     INT mstart1 = ego->mstart1, mend1 = mstart1 + ego->mcount1;

     for (i = 0; i < vl; ++i, IO += vs) {

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

         R *p0 = IO + k * ms;

         R *p1 = IO + (r - k) * ms;

         INT j;

         for (j = mstart1; j < mend1; ++j) {

        E rp, ip, im, rm;

        rp = p0[j * s];

        im = p1[ms - j * s];

        rm = p1[j * s];

        ip = p0[ms - j * s];

        p0[j * s] = rp - im;

        p1[ms - j * s] = rp + im;

        p1[j * s] = rm - ip;

        p0[ms - j * s] = ip + rm;

         }

    }

    swapri(IO, r, m, s, mstart1, mend1);

     }

}

static void reorder_dif(const P *ego, R *IO)

{

     INT i, k;

     INT r = ego->r, m = ego->m, s = ego->s, vl = ego->vl, vs = ego->vs;

     INT ms = m * s;

     INT mstart1 = ego->mstart1, mend1 = mstart1 + ego->mcount1;

     for (i = 0; i < vl; ++i, IO += vs) {

    swapri(IO, r, m, s, mstart1, mend1);

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

         R *p0 = IO + k * ms;

         R *p1 = IO + (r - k) * ms;

         const R half = K(0.5);

         INT j;

         for (j = mstart1; j < mend1; ++j) {

        E rp, ip, im, rm;

        rp = half * p0[j * s];

        im = half * p1[ms - j * s];

        rm = half * p1[j * s];

        ip = half * p0[ms - j * s];

        p0[j * s] = rp + im;

        p1[ms - j * s] = im - rp;

        p1[j * s] = rm + ip;

        p0[ms - j * s] = ip - rm;

         }

    }

     }

}

static int applicable(rdft_kind kind, INT r, INT m, const planner *plnr)

{

     return (1 

       && (kind == R2HC || kind == HC2R)

       && (m % 2)

       && (r % 2)

       && !NO_SLOWP(plnr)

    );

}

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

static void apply_dit(const plan *ego_, R *IO)

{

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

     INT start;

     plan_rdft *cld, *cld0;

     bytwiddle(ego, IO, K(-1.0));

     cld0 = (plan_rdft *) ego->cld0;

     cld0->apply(ego->cld0, IO, IO);

     start = ego->mstart1 * ego->s;

     cld = (plan_rdft *) ego->cld;

     cld->apply(ego->cld, IO + start, IO + start);

     reorder_dit(ego, IO);

}

static void apply_dif(const plan *ego_, R *IO)

{

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

     INT start;

     plan_rdft *cld, *cld0;

     reorder_dif(ego, IO);

     cld0 = (plan_rdft *) ego->cld0;

     cld0->apply(ego->cld0, IO, IO);

     start = ego->mstart1 * ego->s;

     cld = (plan_rdft *) ego->cld;

     cld->apply(ego->cld, IO + start, IO + start);

     bytwiddle(ego, IO, K(1.0));

}

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

{

     P *ego = (P *) ego_;

     X(plan_awake)(ego->cld0, wakefulness);

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

     mktwiddle(ego, wakefulness);

}

static void destroy(plan *ego_)

{

     P *ego = (P *) ego_;

     X(plan_destroy_internal)(ego->cld);

     X(plan_destroy_internal)(ego->cld0);

}

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

{

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

     p->print(p, "(hc2hc-generic-%s-%D-%D%v%(%p%)%(%p%))", 

        ego->super.apply == apply_dit ? "dit" : "dif",

        ego->r, ego->m, ego->vl, ego->cld0, ego->cld);

}

static plan *mkcldw(const hc2hc_solver *ego_, 

        rdft_kind kind, INT r, INT m, INT s, INT vl, INT vs, 

        INT mstart, INT mcount,

        R *IO, planner *plnr)

{

     P *pln;

     plan *cld0 = 0, *cld = 0;

     INT mstart1, mcount1, mstride;

     static const plan_adt padt = {

    0, awake, print, destroy

     };

     UNUSED(ego_);

     A(mstart >= 0 && mcount > 0 && mstart + mcount <= (m+2)/2);

     if (!applicable(kind, r, m, plnr))

          return (plan *)0;

     A(m % 2);

     mstart1 = mstart + (mstart == 0);

     mcount1 = mcount - (mstart == 0);

     mstride = m - (mstart + mcount - 1) - mstart1;

     /* 0th (DC) transform (vl of these), if mstart == 0 */

     cld0 = X(mkplan_d)(plnr, 

      X(mkproblem_rdft_1_d)(

           mstart == 0 ? X(mktensor_1d)(r, m * s, m * s)

           : X(mktensor_0d)(),

           X(mktensor_1d)(vl, vs, vs),

           IO, IO, kind)

      );

     if (!cld0) goto nada;

     /* twiddle transforms: there are 2 x mcount1 x vl of these

  (where 2 corresponds to the real and imaginary parts) ...

        the 2 x mcount1 loops are combined if mstart=0 and mcount=(m+2)/2. */

     cld = X(mkplan_d)(plnr, 

      X(mkproblem_rdft_1_d)(

           X(mktensor_1d)(r, m * s, m * s),

           X(mktensor_3d)(2, mstride * s, mstride * s,

              mcount1, s, s, 

              vl, vs, vs),

           IO + s * mstart1, IO + s * mstart1, kind)

                  );

     if (!cld) goto nada;

     pln = MKPLAN_HC2HC(P, &padt, (kind == R2HC) ? apply_dit : apply_dif);

     pln->cld = cld;

     pln->cld0 = cld0;

     pln->r = r;

     pln->m = m;

     pln->s = s;

     pln->vl = vl;

     pln->vs = vs;

     pln->td = 0;

     pln->mstart1 = mstart1;

     pln->mcount1 = mcount1;

     {

    double n0 = 0.5 * (r - 1) * (2 * mcount1) * vl;

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

    pln->super.super.ops.mul += (kind == R2HC ? 5.0 : 7.0) * n0;

    pln->super.super.ops.add += 4.0 * n0;

    pln->super.super.ops.other += 11.0 * n0;

     }

     return &(pln->super.super);

 nada:

     X(plan_destroy_internal)(cld);

     X(plan_destroy_internal)(cld0);

     return (plan *) 0;

}

static void regsolver(planner *plnr, INT r)

{

     S *slv = (S *)X(mksolver_hc2hc)(sizeof(S), r, mkcldw);

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

     if (X(mksolver_hc2hc_hook)) {

    slv = (S *)X(mksolver_hc2hc_hook)(sizeof(S), r, mkcldw);

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

     }

}

void X(hc2hc_generic_register)(planner *p)

{

     regsolver(p, 0);

}