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/* mpfr_cmp_ui -- compare a floating-point number with a machine integer
Copyright 1999, 2001, 2002 Free Software Foundation, Inc.
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 "longlong.h"
#include "mpfr.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
*/
int
mpfr_cmp_ui_2exp (mpfr_srcptr b, unsigned long int i, int f)
{
int e, k, bn;
mp_limb_t c, *bp;
MPFR_ASSERTN(!MPFR_IS_NAN(b));
if (MPFR_IS_INF(b))
return MPFR_SIGN(b);
/* now b is neither NaN nor +/-Infinity */
if (MPFR_IS_ZERO(b))
return i ? -1 : 0;
else if (MPFR_SIGN(b) < 0)
return -1;
/* now b>0 */
else if (i == 0)
return 1;
else
{ /* b>0, i>0 */
e = MPFR_EXP(b); /* 2^(e-1) <= b < 2^e */
if (e > f + BITS_PER_MP_LIMB)
return 1;
c = (mp_limb_t) i;
count_leading_zeros(k, c);
k = f + BITS_PER_MP_LIMB - k; /* 2^(k-1) <= i*2^f < 2^k */
if (k != e)
return e - k;
/* now k=e */
c <<= f + BITS_PER_MP_LIMB - k;
bn = (MPFR_PREC(b) - 1) / BITS_PER_MP_LIMB;
bp = MPFR_MANT(b) + bn;
if (*bp > c)
return 1;
if (*bp < c)
return -1;
/* most significant limbs agree, check remaining limbs from b */
while (--bn >= 0)
if (*--bp)
return 1;
return 0;
}
}
/* returns a positive value if b>i*2^f,
a negative value if b<i*2^f,
zero if b=i*2^f
*/
int
mpfr_cmp_si_2exp (mpfr_srcptr b, long int i, int f)
{
int e, k, bn, si;
mp_limb_t c, *bp;
MPFR_ASSERTN(!MPFR_IS_NAN(b));
si = i < 0 ? -1 : 1; /* sign of i */
if (MPFR_IS_INF(b) || (MPFR_NOTZERO(b) && MPFR_SIGN(b) != si))
return MPFR_SIGN(b);
/* both signs differ */
else if (MPFR_IS_ZERO(b) || i == 0)
return i == 0 ? (MPFR_IS_ZERO(b) ? 0 : MPFR_SIGN(b)) : -si;
else
{ /* b and i are of same sign */
e = MPFR_EXP(b); /* 2^(e-1) <= b < 2^e */
if (e > f + BITS_PER_MP_LIMB)
return si;
c = i < 0 ? - (mp_limb_t) i : (mp_limb_t) i;
count_leading_zeros(k, c);
k = f + BITS_PER_MP_LIMB - k; /* 2^(k-1) <= i*2^f < 2^k */
if (k != e)
return si * (e - k);
/* now k = e */
c <<= f + BITS_PER_MP_LIMB - k;
bn = (MPFR_PREC(b) - 1) / BITS_PER_MP_LIMB;
bp = MPFR_MANT(b) + bn;
if (*bp > c)
return si;
if (*bp < c)
return -si;
/* most significant limbs agree, check remaining limbs from b */
while (--bn >= 0)
if (*--bp)
return si;
return 0;
}
}
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