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/* mpfr_eq -- Compare two floats up to a specified bit #.
Copyright 1999, 2001, 2003 Free Software Foundation, Inc.
(Copied from GNU MP, file mpf_eq.)
This file is part of the MPFR Library.
The MPFR Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.
The MPFR Library 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 Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the MPFR Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include <stdio.h>
#include "gmp.h"
#include "gmp-impl.h"
#include "mpfr.h"
#include "mpfr-impl.h"
/* return non-zero if the first n_bits bits of u, v are equal,
0 otherwise */
int
mpfr_eq (mpfr_srcptr u, mpfr_srcptr v, unsigned long int n_bits)
{
mp_srcptr up, vp;
mp_size_t usize, vsize, size, i;
mp_exp_t uexp, vexp;
int k;
if (MPFR_ARE_SINGULAR(u, v))
{
if (MPFR_IS_NAN(u) || MPFR_IS_NAN(v))
return 0; /* non equal */
else if (MPFR_IS_INF(u) && MPFR_IS_INF(v))
return (MPFR_SIGN(u) == MPFR_SIGN(v));
else if (MPFR_IS_ZERO(u) && MPFR_IS_ZERO(v))
return 1;
else
return 0;
}
/* 1. Are the signs different? */
if (MPFR_SIGN(u) != MPFR_SIGN(v))
return 0;
uexp = MPFR_GET_EXP (u);
vexp = MPFR_GET_EXP (v);
/* 2. Are the exponents different? */
if (uexp != vexp)
return 0; /* no bit agree */
usize = (MPFR_PREC(u) - 1) / BITS_PER_MP_LIMB + 1;
vsize = (MPFR_PREC(v) - 1) / BITS_PER_MP_LIMB + 1;
up = MPFR_MANT(u);
vp = MPFR_MANT(v);
if (usize > vsize)
{
if ((unsigned long) vsize * BITS_PER_MP_LIMB < n_bits)
{
k = usize - vsize - 1;
while (k >= 0 && !up[k]) --k;
if (k >= 0)
return 0; /* surely too different */
}
size = vsize;
}
else if (vsize > usize)
{
if ((unsigned long) usize * BITS_PER_MP_LIMB < n_bits)
{
k = vsize - usize - 1;
while (k >= 0 && !vp[k]) --k;
if (k >= 0)
return 0; /* surely too different */
}
size = usize;
}
else
{
size = usize;
}
/* now size = min (usize, vsize) */
if ((unsigned long)size > (n_bits + BITS_PER_MP_LIMB-1) / BITS_PER_MP_LIMB)
size = (n_bits + BITS_PER_MP_LIMB-1) / BITS_PER_MP_LIMB;
up += usize - size;
vp += vsize - size;
for (i = size - 1; i > 0 && n_bits >= BITS_PER_MP_LIMB; i--)
{
if (up[i] != vp[i])
return 0;
n_bits -= BITS_PER_MP_LIMB;
}
/* now either i=0 or n_bits<BITS_PER_MP_LIMB */
if (n_bits > BITS_PER_MP_LIMB)
return mpfr_cmp (u, v) == 0;
if (n_bits & (BITS_PER_MP_LIMB - 1))
return (up[i] >> (BITS_PER_MP_LIMB - (n_bits & (BITS_PER_MP_LIMB - 1))) ==
vp[i] >> (BITS_PER_MP_LIMB - (n_bits & (BITS_PER_MP_LIMB - 1))));
else
return (up[i] == vp[i]);
}
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