pqc/external/flint-2.4.3/fmpz/comb_init.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) 2008, 2009, William Hart
Copyright (C) 2010 Fredrik Johansson
******************************************************************************/
#include <gmp.h>
#include "flint.h"
#include "ulong_extras.h"
#include "fmpz.h"
#include "nmod_vec.h"
#include "fmpz_vec.h"
void fmpz_comb_temp_init(fmpz_comb_temp_t temp, const fmpz_comb_t comb)
{
slong n, i, j;
/* Allocate space for comb_temp */
temp->n = n = comb->n;
temp->comb_temp = (fmpz **) flint_malloc(n * sizeof(fmpz *));
j = (WORD(1) << (n - 1));
for (i = 0; i < n; i++)
{
temp->comb_temp[i] = _fmpz_vec_init(j);
j /= 2;
}
fmpz_init(temp->temp);
fmpz_init(temp->temp2);
}
void
fmpz_comb_init(fmpz_comb_t comb, mp_srcptr primes, slong num_primes)
{
slong i, j;
slong n, num;
ulong log_comb, log_res;
fmpz_t temp, temp2;
comb->primes = primes;
comb->num_primes = num_primes;
n = FLINT_BIT_COUNT(num_primes);
comb->n = n;
/* Create nmod_poly modulus information */
comb->mod = (nmod_t *) flint_malloc(sizeof(nmod_t) * num_primes);
for (i = 0; i < num_primes; i++)
nmod_init(&comb->mod[i], primes[i]);
/* Nothing to do */
if (n == 0)
return;
/* Allocate space for comb and res */
comb->comb = (fmpz **) flint_malloc(n * sizeof(fmpz *));
comb->res = (fmpz **) flint_malloc(n * sizeof(fmpz *));
/* Size of top level */
j = (WORD(1) << (n - 1));
/* Initialise arrays at each level */
for (i = 0; i < n; i++)
{
comb->comb[i] = _fmpz_vec_init(j);
comb->res[i] = _fmpz_vec_init(j);
j /= 2;
}
/* Compute products of pairs of primes and place in comb */
for (i = 0, j = 0; i + 2 <= num_primes; i += 2, j++)
{
fmpz_set_ui(comb->comb[0] + j, primes[i]);
fmpz_mul_ui(comb->comb[0] + j, comb->comb[0] + j, primes[i+1]);
}
/* In case number of primes is odd */
if (i < num_primes)
{
fmpz_set_ui(comb->comb[0] + j, primes[i]);
i += 2;
j++;
}
/* Set the rest of the entries on that row of the comb to 1 */
num = (WORD(1) << n);
for (; i < num; i += 2, j++)
{
fmpz_one(comb->comb[0] + j);
}
/* Compute rest of comb by multiplying in pairs */
log_comb = 1;
num /= 2;
while (num >= 2)
{
for (i = 0, j = 0; i < num; i += 2, j++)
{
fmpz_mul(comb->comb[log_comb] + j, comb->comb[log_comb-1] + i,
comb->comb[log_comb-1] + i + 1);
}
log_comb++;
num /= 2;
}
/* Compute inverses from pairs of primes */
fmpz_init(temp);
fmpz_init(temp2);
for (i = 0, j = 0; i + 2 <= num_primes; i += 2, j++)
{
fmpz_set_ui(temp, primes[i]);
fmpz_set_ui(temp2, primes[i+1]);
fmpz_invmod(comb->res[0] + j, temp, temp2);
}
fmpz_clear(temp);
fmpz_clear(temp2);
/* Compute remaining inverses, each level
combining pairs from the level below */
log_res = 1;
num = (WORD(1) << (n - 1));
while (log_res < n)
{
for (i = 0, j = 0; i < num; i += 2, j++)
{
fmpz_invmod(comb->res[log_res] + j, comb->comb[log_res-1] + i,
comb->comb[log_res-1] + i + 1);
}
log_res++;
num /= 2;
}
}