pqc/external/flint-2.4.3/fmpz/multi_mod_ui.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"
void
fmpz_multi_mod_ui_basecase(mp_limb_t * out, const fmpz_t in, mp_srcptr primes,
slong num_primes)
{
slong i;
for (i = 0; i < num_primes; i++)
{
out[i] = fmpz_fdiv_ui(in, primes[i]);
}
}
void
fmpz_multi_mod_ui(mp_limb_t * out, const fmpz_t in, const fmpz_comb_t comb,
fmpz_comb_temp_t temp)
{
slong i, j;
slong n = comb->n;
slong log_comb;
slong stride;
slong num;
slong num_primes = comb->num_primes;
fmpz ** comb_temp = temp->comb_temp;
if (num_primes == 1)
{
out[0] = fmpz_fdiv_ui(in, comb->primes[0]);
return;
}
log_comb = n - 1;
/* Find level in comb with entries bigger than the input integer */
log_comb = 0;
if (fmpz_sgn(in) < 0)
{
while ((fmpz_bits(in) >= fmpz_bits(comb->comb[log_comb]) - 1)
&& (log_comb < comb->n - 1)) log_comb++;
}
else
{
while (fmpz_cmpabs(in, comb->comb[log_comb]) >= 0 &&
(log_comb < comb->n - 1))
log_comb++;
}
num = (WORD(1) << (n - log_comb - 1));
/* Set each entry of this level of temp to the input integer */
for (i = 0; i < num; i++)
{
fmpz_set(comb_temp[log_comb] + i, in);
}
log_comb--;
num *= 2;
/* Fill in other entries of temp by taking entries of temp
at higher level mod pairs from comb */
/* keep going until we reach the basecase */
while (log_comb > FLINT_FMPZ_LOG_MULTI_MOD_CUTOFF)
{
for (i = 0, j = 0; i < num; i += 2, j++)
{
fmpz_mod(comb_temp[log_comb] + i, comb_temp[log_comb + 1] + j,
comb->comb[log_comb] + i);
fmpz_mod(comb_temp[log_comb] + i + 1, comb_temp[log_comb + 1] + j,
comb->comb[log_comb] + i + 1);
}
num *= 2;
log_comb--;
}
/* Do basecase */
num /= 2;
log_comb++;
stride = (WORD(1) << (log_comb + 1));
for (i = 0, j = 0; j < num_primes; i++, j += stride)
{
fmpz_multi_mod_ui_basecase(out + j, comb_temp[log_comb] + i,
comb->primes + j, FLINT_MIN(stride, num_primes - j));
}
}