furnace/extern/fftw/kernel/twiddle.c

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/*
* 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
*
*/
/* Twiddle manipulation */
#include "kernel/ifftw.h"
#include <math.h>
#define HASHSZ 109
/* hash table of known twiddle factors */
static twid *twlist[HASHSZ];
static INT hash(INT n, INT r)
{
INT h = n * 17 + r;
if (h < 0) h = -h;
return (h % HASHSZ);
}
static int equal_instr(const tw_instr *p, const tw_instr *q)
{
if (p == q)
return 1;
for (;; ++p, ++q) {
if (p->op != q->op)
return 0;
switch (p->op) {
case TW_NEXT:
return (p->v == q->v); /* p->i is ignored */
case TW_FULL:
case TW_HALF:
if (p->v != q->v) return 0; /* p->i is ignored */
break;
default:
if (p->v != q->v || p->i != q->i) return 0;
break;
}
}
A(0 /* can't happen */);
}
static int ok_twid(const twid *t,
enum wakefulness wakefulness,
const tw_instr *q, INT n, INT r, INT m)
{
return (wakefulness == t->wakefulness &&
n == t->n &&
r == t->r &&
m <= t->m &&
equal_instr(t->instr, q));
}
static twid *lookup(enum wakefulness wakefulness,
const tw_instr *q, INT n, INT r, INT m)
{
twid *p;
for (p = twlist[hash(n,r)];
p && !ok_twid(p, wakefulness, q, n, r, m);
p = p->cdr)
;
return p;
}
static INT twlen0(INT r, const tw_instr *p, INT *vl)
{
INT ntwiddle = 0;
/* compute length of bytecode program */
A(r > 0);
for ( ; p->op != TW_NEXT; ++p) {
switch (p->op) {
case TW_FULL:
ntwiddle += (r - 1) * 2;
break;
case TW_HALF:
ntwiddle += (r - 1);
break;
case TW_CEXP:
ntwiddle += 2;
break;
case TW_COS:
case TW_SIN:
ntwiddle += 1;
break;
}
}
*vl = (INT)p->v;
return ntwiddle;
}
INT X(twiddle_length)(INT r, const tw_instr *p)
{
INT vl;
return twlen0(r, p, &vl);
}
static R *compute(enum wakefulness wakefulness,
const tw_instr *instr, INT n, INT r, INT m)
{
INT ntwiddle, j, vl;
R *W, *W0;
const tw_instr *p;
triggen *t = X(mktriggen)(wakefulness, n);
p = instr;
ntwiddle = twlen0(r, p, &vl);
A(m % vl == 0);
W0 = W = (R *)MALLOC((ntwiddle * (m / vl)) * sizeof(R), TWIDDLES);
for (j = 0; j < m; j += vl) {
for (p = instr; p->op != TW_NEXT; ++p) {
switch (p->op) {
case TW_FULL: {
INT i;
for (i = 1; i < r; ++i) {
A((j + (INT)p->v) * i < n);
A((j + (INT)p->v) * i > -n);
t->cexp(t, (j + (INT)p->v) * i, W);
W += 2;
}
break;
}
case TW_HALF: {
INT i;
A((r % 2) == 1);
for (i = 1; i + i < r; ++i) {
t->cexp(t, MULMOD(i, (j + (INT)p->v), n), W);
W += 2;
}
break;
}
case TW_COS: {
R d[2];
A((j + (INT)p->v) * p->i < n);
A((j + (INT)p->v) * p->i > -n);
t->cexp(t, (j + (INT)p->v) * (INT)p->i, d);
*W++ = d[0];
break;
}
case TW_SIN: {
R d[2];
A((j + (INT)p->v) * p->i < n);
A((j + (INT)p->v) * p->i > -n);
t->cexp(t, (j + (INT)p->v) * (INT)p->i, d);
*W++ = d[1];
break;
}
case TW_CEXP:
A((j + (INT)p->v) * p->i < n);
A((j + (INT)p->v) * p->i > -n);
t->cexp(t, (j + (INT)p->v) * (INT)p->i, W);
W += 2;
break;
}
}
}
X(triggen_destroy)(t);
return W0;
}
static void mktwiddle(enum wakefulness wakefulness,
twid **pp, const tw_instr *instr, INT n, INT r, INT m)
{
twid *p;
INT h;
if ((p = lookup(wakefulness, instr, n, r, m))) {
++p->refcnt;
} else {
p = (twid *) MALLOC(sizeof(twid), TWIDDLES);
p->n = n;
p->r = r;
p->m = m;
p->instr = instr;
p->refcnt = 1;
p->wakefulness = wakefulness;
p->W = compute(wakefulness, instr, n, r, m);
/* cons! onto twlist */
h = hash(n, r);
p->cdr = twlist[h];
twlist[h] = p;
}
*pp = p;
}
static void twiddle_destroy(twid **pp)
{
twid *p = *pp;
twid **q;
if ((--p->refcnt) == 0) {
/* remove p from twiddle list */
for (q = &twlist[hash(p->n, p->r)]; *q; q = &((*q)->cdr)) {
if (*q == p) {
*q = p->cdr;
X(ifree)(p->W);
X(ifree)(p);
*pp = 0;
return;
}
}
A(0 /* can't happen */ );
}
}
void X(twiddle_awake)(enum wakefulness wakefulness, twid **pp,
const tw_instr *instr, INT n, INT r, INT m)
{
switch (wakefulness) {
case SLEEPY:
twiddle_destroy(pp);
break;
default:
mktwiddle(wakefulness, pp, instr, n, r, m);
break;
}
}