pqc/external/flint-2.4.3/long_extras/randtest.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) 2010 Sebastian Pancratz
******************************************************************************/
#include <limits.h>
#include <gmp.h>
#include "flint.h"
#include "fmpz.h"
#include "ulong_extras.h"
mp_limb_signed_t z_randtest(flint_rand_t state)
{
mp_limb_t m;
mp_limb_signed_t z;
m = n_randlimb(state);
if (m & UWORD(7))
{
z = n_randbits(state, n_randint(state, FLINT_BITS));
}
else
{
m >>= 3;
switch (m % UWORD(7))
{
case 0: z = 0; break;
case 1: z = 1; break;
case 2: z = -1; break;
case 3: z = COEFF_MAX; break;
case 4: z = COEFF_MIN; break;
case 5: z = WORD_MAX; break;
case 6: z = WORD_MIN; break;
default: z = 0;
}
}
return z;
}
mp_limb_signed_t z_randtest_not_zero(flint_rand_t state)
{
mp_limb_signed_t z;
while ((z = z_randtest(state)) == 0) ;
return z;
}