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

58 lines
2.0 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
******************************************************************************/
#define ulong ulongxx /* interferes with system includes */
#include <math.h>
#undef ulong
#define ulong mp_limb_t
#include <gmp.h>
#include "flint.h"
#include "ulong_extras.h"
int mod64[64] = {1,1,0,0,1,0,0,0,0,1,0,0,0,0,0,0,1,1,0,0,0,
0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,1,0,0,0,0,1,
0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0};
int mod65[65] = {1,1,0,0,1,0,0,0,0,1,1,0,0,0,1,0,1,0,0,0,0,0,
0,0,0,1,1,0,0,1,1,0,0,0,0,1,1,0,0,1,1,0,0,0,
0,0,0,0,0,1,0,1,0,0,0,1,1,0,0,0,0,1,0,0,1};
int mod63[63] = {1,1,0,0,1,0,0,1,0,1,0,0,0,0,1,0,1,0,1,0,0,
0,1,0,0,1,0,0,1,0,0,0,0,0,0,1,1,1,0,0,0,0,
0,1,0,0,1,0,0,1,0,0,0,0,0,0,1,0,1,0,0,0,0};
int n_is_square(mp_limb_t x)
{
mp_limb_t sq;
if (!mod64[x % UWORD(64)]) return 0;
if (!mod63[x % UWORD(63)]) return 0;
if (!mod65[x % UWORD(65)]) return 0;
sq = (mp_limb_t) (sqrt((double) x) + 0.5);
return (x == sq*sq);
}