pqc/external/flint-2.4.3/fmpz/randm.c
2014-05-24 23:16:06 +02:00

56 lines
1.8 KiB
C

/*=============================================================================
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) 2009 William Hart
Copyright (C) 2010, 2012 Sebastian Pancratz
******************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <gmp.h>
#include "flint.h"
#include "ulong_extras.h"
#include "fmpz.h"
void
fmpz_randm(fmpz_t f, flint_rand_t state, const fmpz_t m)
{
mp_bitcnt_t bits = fmpz_bits(m);
int sgn = fmpz_sgn(m);
if (bits <= FLINT_BITS - 2)
{
_fmpz_demote(f);
*f = (sgn >= 0) ? n_randint(state, *m) : - n_randint(state, -(*m));
}
else
{
__mpz_struct *mpz_ptr = _fmpz_promote(f);
_flint_rand_init_gmp(state);
mpz_urandomm(mpz_ptr, state->gmp_state, COEFF_TO_PTR(*m));
if (sgn < 0)
mpz_neg(mpz_ptr, mpz_ptr);
_fmpz_demote_val(f);
}
}