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

82 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) 2012 Fredrik Johansson
******************************************************************************/
#include "fmpq.h"
int
_fmpq_cmp(const fmpz_t p, const fmpz_t q, const fmpz_t r, const fmpz_t s)
{
int s1, s2, res;
mp_bitcnt_t bp, bq, br, bs;
fmpz_t t, u;
if (fmpz_equal(q, s))
return fmpz_cmp(p, r);
s1 = fmpz_sgn(p);
s2 = fmpz_sgn(r);
if (s1 != s2)
return s1 < s2 ? -1 : 1;
if (s1 == 0)
return -s2;
if (s2 == 0)
return -s1;
bp = fmpz_bits(p);
bq = fmpz_bits(q);
br = fmpz_bits(r);
bs = fmpz_bits(s);
if (bp + bs + 1 < br + bq)
return -s1;
if (bp + bs > br + bq + 1)
return s1;
fmpz_init(t);
fmpz_init(u);
fmpz_mul(t, p, s);
fmpz_mul(u, q, r);
res = fmpz_cmp(t, u);
fmpz_clear(t);
fmpz_clear(u);
return res;
}
int
fmpq_cmp(const fmpq_t x, const fmpq_t y)
{
return _fmpq_cmp(fmpq_numref(x), fmpq_denref(x),
fmpq_numref(y), fmpq_denref(y));
}