pqc/external/flint-2.4.3/fq_poly_templates/compose_divconquer.c

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2014-05-18 22:03:37 +00:00
/*=============================================================================
This file is part of FLINT.
FLINT 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.
FLINT 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 FLINT; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2012 Sebastian Pancratz
Copyright (C) 2013 Mike Hansen
******************************************************************************/
#ifdef T
#include "templates.h"
void
_TEMPLATE(T, poly_compose_divconquer) (
TEMPLATE(T, struct) * rop,
const TEMPLATE(T, struct) * op1, slong len1,
const TEMPLATE(T, struct) * op2, slong len2,
const TEMPLATE(T, ctx_t) ctx)
{
slong i, j, k, n;
slong *hlen, alloc, powlen;
TEMPLATE(T, struct) * v, **h, *pow, *temp;
if (len1 <= 2 || len2 <= 1)
{
if (len1 == 1)
TEMPLATE(T, set) (rop, op1, ctx);
else if (len2 == 1)
_TEMPLATE(T, TEMPLATE(poly_evaluate, T)) (rop, op1, len1, op2,
ctx);
else /* len1 == 2 */
_TEMPLATE(T, poly_compose_horner) (rop, op1, len1, op2, len2, ctx);
return;
}
/* Initialisation */
hlen = (slong *) flint_malloc(((len1 + 1) / 2) * sizeof(slong));
k = FLINT_CLOG2(len1) - 1;
hlen[0] = hlen[1] = ((1 << k) - 1) * (len2 - 1) + 1;
for (i = k - 1; i > 0; i--)
{
slong hi = (len1 + (1 << i) - 1) / (1 << i);
for (n = (hi + 1) / 2; n < hi; n++)
hlen[n] = ((1 << i) - 1) * (len2 - 1) + 1;
}
powlen = (1 << k) * (len2 - 1) + 1;
alloc = 0;
for (i = 0; i < (len1 + 1) / 2; i++)
alloc += hlen[i];
v = _TEMPLATE(T, vec_init) (alloc + 2 * powlen, ctx);
h = (TEMPLATE(T, struct) **) flint_malloc(((len1 + 1) / 2) *
sizeof(TEMPLATE(T, struct) *));
h[0] = v;
for (i = 0; i < (len1 - 1) / 2; i++)
{
h[i + 1] = h[i] + hlen[i];
hlen[i] = 0;
}
hlen[(len1 - 1) / 2] = 0;
pow = v + alloc;
temp = pow + powlen;
/* Let's start the actual work */
for (i = 0, j = 0; i < len1 / 2; i++, j += 2)
{
if (!TEMPLATE(T, is_zero) (op1 + (j + 1), ctx))
{
_TEMPLATE(T, TEMPLATE(poly_scalar_mul, T)) (h[i], op2, len2,
op1 + j + 1, ctx);
TEMPLATE(T, add) (h[i], h[i], op1 + j, ctx);
hlen[i] = len2;
}
else if (!TEMPLATE(T, is_zero) (op1 + j, ctx))
{
TEMPLATE(T, set) (h[i], op1 + j, ctx);
hlen[i] = 1;
}
}
if ((len1 & WORD(1)))
{
if (!TEMPLATE(T, is_zero) (op1 + j, ctx))
{
TEMPLATE(T, set) (h[i], op1 + j, ctx);
hlen[i] = 1;
}
}
_TEMPLATE(T, poly_sqr) (pow, op2, len2, ctx);
powlen = 2 * len2 - 1;
for (n = (len1 + 1) / 2; n > 2; n = (n + 1) / 2)
{
if (hlen[1] > 0)
{
slong templen = powlen + hlen[1] - 1;
_TEMPLATE(T, poly_mul) (temp, pow, powlen, h[1], hlen[1], ctx);
_TEMPLATE(T, poly_add) (h[0], temp, templen, h[0], hlen[0], ctx);
hlen[0] = FLINT_MAX(hlen[0], templen);
}
for (i = 1; i < n / 2; i++)
{
if (hlen[2 * i + 1] > 0)
{
_TEMPLATE(T, poly_mul) (h[i], pow, powlen, h[2 * i + 1],
hlen[2 * i + 1], ctx);
hlen[i] = hlen[2 * i + 1] + powlen - 1;
}
else
hlen[i] = 0;
_TEMPLATE(T, poly_add) (h[i], h[i], hlen[i], h[2 * i], hlen[2 * i],
ctx);
hlen[i] = FLINT_MAX(hlen[i], hlen[2 * i]);
}
if ((n & WORD(1)))
{
_TEMPLATE(T, poly_set) (h[i], h[2 * i], hlen[2 * i], ctx);
hlen[i] = hlen[2 * i];
}
_TEMPLATE(T, poly_sqr) (temp, pow, powlen, ctx);
powlen += powlen - 1;
{
TEMPLATE(T, struct) * t = pow;
pow = temp;
temp = t;
}
}
_TEMPLATE(T, poly_mul) (rop, pow, powlen, h[1], hlen[1], ctx);
_TEMPLATE(T, poly_add) (rop, rop, hlen[0], h[0], hlen[0], ctx);
_TEMPLATE(T, vec_clear) (v, alloc + 2 * powlen, ctx);
flint_free(h);
flint_free(hlen);
}
void
TEMPLATE(T, poly_compose_divconquer) (TEMPLATE(T, poly_t) rop,
const TEMPLATE(T, poly_t) op1,
const TEMPLATE(T, poly_t) op2,
const TEMPLATE(T, ctx_t) ctx)
{
const slong len1 = op1->length;
const slong len2 = op2->length;
const slong lenr = (len1 - 1) * (len2 - 1) + 1;
if (len1 == 0)
{
TEMPLATE(T, poly_zero) (rop, ctx);
}
else if (len1 == 1 || len2 == 0)
{
TEMPLATE(T, TEMPLATE(poly_set, T)) (rop, op1->coeffs + 0, ctx);
}
else if (rop != op1 && rop != op2)
{
TEMPLATE(T, poly_fit_length) (rop, lenr, ctx);
_TEMPLATE(T, poly_compose_divconquer) (rop->coeffs, op1->coeffs, len1,
op2->coeffs, len2, ctx);
_TEMPLATE(T, poly_set_length) (rop, lenr, ctx);
_TEMPLATE(T, poly_normalise) (rop, ctx);
}
else
{
TEMPLATE(T, poly_t) t;
TEMPLATE(T, poly_init2) (t, lenr, ctx);
_TEMPLATE(T, poly_compose_divconquer) (t->coeffs, op1->coeffs, len1,
op2->coeffs, len2, ctx);
_TEMPLATE(T, poly_set_length) (t, lenr, ctx);
_TEMPLATE(T, poly_normalise) (t, ctx);
TEMPLATE(T, poly_swap) (rop, t, ctx);
TEMPLATE(T, poly_clear) (t, ctx);
}
}
#endif