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/* mpfr_cmp_ui -- compare a floating-point number with a machine integer
Copyright (C) 1999, 2001 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;
if (MPFR_IS_NAN(b)) return 1;
if (MPFR_IS_INF(b)) return (MPFR_SIGN(b) > 0) ? 1 : -1;
/* now b is neither NaN nor +/-Infinity */
if (!MPFR_NOTZERO(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;
else 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;
if (MPFR_IS_NAN(b)) return 1;
si = (i<0) ? -1 : 1; /* sign of i */
if (MPFR_SIGN(b) * i < 0 || MPFR_IS_INF(b)) return MPFR_SIGN(b);
/* both signs differ */
else if (!MPFR_NOTZERO(b) || (i==0)) { /* one is zero */
if (i==0) return ((MPFR_NOTZERO(b)) ? MPFR_SIGN(b) : 0);
else return si; /* b is zero */
}
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 = (mp_limb_t) ((i<0) ? -i : 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;
else 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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