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/* mpf_ceil, mpf_floor -- round an mpf to an integer.
Copyright 2001, 2004 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP 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 MP 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 MP Library. If not, see http://www.gnu.org/licenses/. */
#include "gmp.h"
#include "gmp-impl.h"
/* dir==1 for ceil, dir==-1 for floor
Notice the use of prec+1 ensures mpf_ceil and mpf_floor are equivalent to
mpf_set if u is already an integer. */
static void __gmpf_ceil_or_floor __GMP_PROTO ((REGPARM_2_1 (mpf_ptr, mpf_srcptr, int))) REGPARM_ATTR (1);
#define mpf_ceil_or_floor(r,u,dir) __gmpf_ceil_or_floor (REGPARM_2_1 (r, u, dir))
REGPARM_ATTR (1) static void
mpf_ceil_or_floor (mpf_ptr r, mpf_srcptr u, int dir)
{
mp_ptr rp, up, p;
mp_size_t size, asize, prec;
mp_exp_t exp;
size = SIZ(u);
if (size == 0)
{
zero:
SIZ(r) = 0;
EXP(r) = 0;
return;
}
rp = PTR(r);
exp = EXP(u);
if (exp <= 0)
{
/* u is only a fraction */
if ((size ^ dir) < 0)
goto zero;
rp[0] = 1;
EXP(r) = 1;
SIZ(r) = dir;
return;
}
EXP(r) = exp;
up = PTR(u);
asize = ABS (size);
up += asize;
/* skip fraction part of u */
asize = MIN (asize, exp);
/* don't lose precision in the copy */
prec = PREC (r) + 1;
/* skip excess over target precision */
asize = MIN (asize, prec);
up -= asize;
if ((size ^ dir) >= 0)
{
/* rounding direction matches sign, must increment if ignored part is
non-zero */
for (p = PTR(u); p != up; p++)
{
if (*p != 0)
{
if (mpn_add_1 (rp, up, asize, CNST_LIMB(1)))
{
/* was all 0xFF..FFs, which have become zeros, giving just
a carry */
rp[0] = 1;
asize = 1;
EXP(r)++;
}
SIZ(r) = (size >= 0 ? asize : -asize);
return;
}
}
}
SIZ(r) = (size >= 0 ? asize : -asize);
if (rp != up)
MPN_COPY_INCR (rp, up, asize);
}
void
mpf_ceil (mpf_ptr r, mpf_srcptr u)
{
mpf_ceil_or_floor (r, u, 1);
}
void
mpf_floor (mpf_ptr r, mpf_srcptr u)
{
mpf_ceil_or_floor (r, u, -1);
}
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