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/* mpfr_cmp_si_2exp -- compare a floating-point number with a signed
machine integer multiplied by a power of 2
Copyright 1999, 2001-2021 Free Software Foundation, Inc.
Contributed by the AriC and Caramba projects, INRIA.
This file is part of the GNU MPFR Library.
The GNU 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 3 of the License, or (at your
option) any later version.
The GNU 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 GNU MPFR Library; see the file COPYING.LESSER. If not, see
https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
#define MPFR_NEED_LONGLONG_H
#include "mpfr-impl.h"
/* returns a positive value if b > i*2^f,
a negative value if b < i*2^f,
zero if b = i*2^f.
b must not be NaN.
*/
int
mpfr_cmp_si_2exp (mpfr_srcptr b, long int i, mpfr_exp_t f)
{
int si;
si = i < 0 ? -1 : 1; /* sign of i */
if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (b)))
{
if (MPFR_IS_INF(b))
return MPFR_INT_SIGN(b);
else if (MPFR_IS_ZERO(b))
return i != 0 ? -si : 0;
/* NAN */
MPFR_SET_ERANGEFLAG ();
return 0;
}
else if (MPFR_SIGN(b) != si || i == 0)
return MPFR_INT_SIGN (b);
else /* b and i are of same sign si */
#ifdef MPFR_LONG_WITHIN_LIMB
{
mpfr_exp_t e;
unsigned long ai;
int k;
mp_size_t bn;
mp_limb_t c, *bp;
ai = SAFE_ABS(unsigned long, i);
/* ai must be representable in a mp_limb_t */
MPFR_ASSERTN(ai == (mp_limb_t) ai);
e = MPFR_GET_EXP (b); /* 2^(e-1) <= b < 2^e */
if (e <= f)
return -si;
if (f < MPFR_EMAX_MAX - GMP_NUMB_BITS &&
e > f + GMP_NUMB_BITS)
return si;
/* now f < e <= f + GMP_NUMB_BITS */
c = (mp_limb_t) ai;
count_leading_zeros(k, c);
if ((int) (e - f) > GMP_NUMB_BITS - k)
return si;
if ((int) (e - f) < GMP_NUMB_BITS - k)
return -si;
/* now b and i*2^f have the same exponent */
c <<= k;
bn = (MPFR_PREC(b) - 1) / GMP_NUMB_BITS;
bp = MPFR_MANT(b);
if (bp[bn] > c)
return si;
if (bp[bn] < c)
return -si;
/* most significant limbs agree, check remaining limbs from b */
while (bn > 0)
if (bp[--bn])
return si;
return 0;
}
#else
{
mpfr_t uu;
int ret;
MPFR_SAVE_EXPO_DECL (expo);
mpfr_init2 (uu, sizeof (unsigned long) * CHAR_BIT);
/* Warning: i*2^f might be outside the current exponent range! */
MPFR_SAVE_EXPO_MARK (expo);
mpfr_set_si_2exp (uu, i, f, MPFR_RNDZ);
MPFR_SAVE_EXPO_FREE (expo);
ret = mpfr_cmp (b, uu);
mpfr_clear (uu);
return ret;
}
#endif /* MPFR_LONG_WITHIN_LIMB */
}
#undef mpfr_cmp_si
int
mpfr_cmp_si (mpfr_srcptr b, long int i)
{
return mpfr_cmp_si_2exp (b, i, 0);
}
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