mirror of
https://github.com/tildearrow/furnace.git
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250 lines
6.3 KiB
C
250 lines
6.3 KiB
C
/*
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* Copyright (c) 2003, 2007-14 Matteo Frigo
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* Copyright (c) 2003, 2007-14 Massachusetts Institute of Technology
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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#include "dft/dft.h"
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typedef struct {
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solver super;
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} S;
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typedef struct {
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plan_dft super;
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INT n; /* problem size */
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INT nb; /* size of convolution */
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R *w; /* lambda k . exp(2*pi*i*k^2/(2*n)) */
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R *W; /* DFT(w) */
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plan *cldf;
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INT is, os;
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} P;
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static void bluestein_sequence(enum wakefulness wakefulness, INT n, R *w)
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{
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INT k, ksq, n2 = 2 * n;
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triggen *t = X(mktriggen)(wakefulness, n2);
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ksq = 0;
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for (k = 0; k < n; ++k) {
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t->cexp(t, ksq, w+2*k);
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/* careful with overflow */
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ksq += 2*k + 1; while (ksq > n2) ksq -= n2;
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}
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X(triggen_destroy)(t);
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}
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static void mktwiddle(enum wakefulness wakefulness, P *p)
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{
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INT i;
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INT n = p->n, nb = p->nb;
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R *w, *W;
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E nbf = (E)nb;
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p->w = w = (R *) MALLOC(2 * n * sizeof(R), TWIDDLES);
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p->W = W = (R *) MALLOC(2 * nb * sizeof(R), TWIDDLES);
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bluestein_sequence(wakefulness, n, w);
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for (i = 0; i < nb; ++i)
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W[2*i] = W[2*i+1] = K(0.0);
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W[0] = w[0] / nbf;
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W[1] = w[1] / nbf;
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for (i = 1; i < n; ++i) {
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W[2*i] = W[2*(nb-i)] = w[2*i] / nbf;
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W[2*i+1] = W[2*(nb-i)+1] = w[2*i+1] / nbf;
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}
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{
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plan_dft *cldf = (plan_dft *)p->cldf;
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/* cldf must be awake */
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cldf->apply(p->cldf, W, W+1, W, W+1);
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}
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}
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static void apply(const plan *ego_, R *ri, R *ii, R *ro, R *io)
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{
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const P *ego = (const P *) ego_;
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INT i, n = ego->n, nb = ego->nb, is = ego->is, os = ego->os;
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R *w = ego->w, *W = ego->W;
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R *b = (R *) MALLOC(2 * nb * sizeof(R), BUFFERS);
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/* multiply input by conjugate bluestein sequence */
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for (i = 0; i < n; ++i) {
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E xr = ri[i*is], xi = ii[i*is];
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E wr = w[2*i], wi = w[2*i+1];
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b[2*i] = xr * wr + xi * wi;
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b[2*i+1] = xi * wr - xr * wi;
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}
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for (; i < nb; ++i) b[2*i] = b[2*i+1] = K(0.0);
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/* convolution: FFT */
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{
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plan_dft *cldf = (plan_dft *)ego->cldf;
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cldf->apply(ego->cldf, b, b+1, b, b+1);
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}
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/* convolution: pointwise multiplication */
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for (i = 0; i < nb; ++i) {
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E xr = b[2*i], xi = b[2*i+1];
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E wr = W[2*i], wi = W[2*i+1];
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b[2*i] = xi * wr + xr * wi;
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b[2*i+1] = xr * wr - xi * wi;
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}
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/* convolution: IFFT by FFT with real/imag input/output swapped */
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{
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plan_dft *cldf = (plan_dft *)ego->cldf;
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cldf->apply(ego->cldf, b, b+1, b, b+1);
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}
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/* multiply output by conjugate bluestein sequence */
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for (i = 0; i < n; ++i) {
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E xi = b[2*i], xr = b[2*i+1];
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E wr = w[2*i], wi = w[2*i+1];
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ro[i*os] = xr * wr + xi * wi;
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io[i*os] = xi * wr - xr * wi;
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}
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X(ifree)(b);
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}
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static void awake(plan *ego_, enum wakefulness wakefulness)
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{
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P *ego = (P *) ego_;
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X(plan_awake)(ego->cldf, wakefulness);
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switch (wakefulness) {
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case SLEEPY:
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X(ifree0)(ego->w); ego->w = 0;
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X(ifree0)(ego->W); ego->W = 0;
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break;
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default:
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A(!ego->w);
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mktwiddle(wakefulness, ego);
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break;
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}
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}
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static int applicable(const solver *ego, const problem *p_,
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const planner *plnr)
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{
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const problem_dft *p = (const problem_dft *) p_;
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UNUSED(ego);
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return (1
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&& p->sz->rnk == 1
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&& p->vecsz->rnk == 0
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/* FIXME: allow other sizes */
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&& X(is_prime)(p->sz->dims[0].n)
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/* FIXME: avoid infinite recursion of bluestein with itself.
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This works because all factors in child problems are 2, 3, 5 */
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&& p->sz->dims[0].n > 16
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&& CIMPLIES(NO_SLOWP(plnr), p->sz->dims[0].n > BLUESTEIN_MAX_SLOW)
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);
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}
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static void destroy(plan *ego_)
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{
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P *ego = (P *) ego_;
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X(plan_destroy_internal)(ego->cldf);
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}
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static void print(const plan *ego_, printer *p)
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{
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const P *ego = (const P *)ego_;
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p->print(p, "(dft-bluestein-%D/%D%(%p%))",
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ego->n, ego->nb, ego->cldf);
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}
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static INT choose_transform_size(INT minsz)
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{
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while (!X(factors_into_small_primes)(minsz))
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++minsz;
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return minsz;
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}
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static plan *mkplan(const solver *ego, const problem *p_, planner *plnr)
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{
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const problem_dft *p = (const problem_dft *) p_;
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P *pln;
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INT n, nb;
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plan *cldf = 0;
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R *buf = (R *) 0;
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static const plan_adt padt = {
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X(dft_solve), awake, print, destroy
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};
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if (!applicable(ego, p_, plnr))
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return (plan *) 0;
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n = p->sz->dims[0].n;
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nb = choose_transform_size(2 * n - 1);
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buf = (R *) MALLOC(2 * nb * sizeof(R), BUFFERS);
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cldf = X(mkplan_f_d)(plnr,
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X(mkproblem_dft_d)(X(mktensor_1d)(nb, 2, 2),
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X(mktensor_1d)(1, 0, 0),
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buf, buf+1,
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buf, buf+1),
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NO_SLOW, 0, 0);
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if (!cldf) goto nada;
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X(ifree)(buf);
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pln = MKPLAN_DFT(P, &padt, apply);
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pln->n = n;
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pln->nb = nb;
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pln->w = 0;
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pln->W = 0;
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pln->cldf = cldf;
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pln->is = p->sz->dims[0].is;
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pln->os = p->sz->dims[0].os;
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X(ops_add)(&cldf->ops, &cldf->ops, &pln->super.super.ops);
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pln->super.super.ops.add += 4 * n + 2 * nb;
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pln->super.super.ops.mul += 8 * n + 4 * nb;
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pln->super.super.ops.other += 6 * (n + nb);
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return &(pln->super.super);
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nada:
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X(ifree0)(buf);
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X(plan_destroy_internal)(cldf);
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return (plan *)0;
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}
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static solver *mksolver(void)
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{
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static const solver_adt sadt = { PROBLEM_DFT, mkplan, 0 };
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S *slv = MKSOLVER(S, &sadt);
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return &(slv->super);
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}
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void X(dft_bluestein_register)(planner *p)
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{
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REGISTER_SOLVER(p, mksolver());
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}
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