118 lines
3.0 KiB
C
118 lines
3.0 KiB
C
/* mpf_ceil, mpf_floor -- round an mpf to an integer.
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Copyright 2001, 2004 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include "gmp.h"
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#include "gmp-impl.h"
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/* dir==1 for ceil, dir==-1 for floor
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Notice the use of prec+1 ensures mpf_ceil and mpf_floor are equivalent to
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mpf_set if u is already an integer. */
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static void __gmpf_ceil_or_floor _PROTO ((REGPARM_2_1 (mpf_ptr r, mpf_srcptr u, int dir))) REGPARM_ATTR (1);
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#define mpf_ceil_or_floor(r,u,dir) __gmpf_ceil_or_floor (REGPARM_2_1 (r, u, dir))
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REGPARM_ATTR (1) static void
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mpf_ceil_or_floor (mpf_ptr r, mpf_srcptr u, int dir)
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{
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mp_ptr rp, up, p;
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mp_size_t size, asize, prec;
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mp_exp_t exp;
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size = SIZ(u);
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if (size == 0)
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{
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zero:
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SIZ(r) = 0;
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EXP(r) = 0;
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return;
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}
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rp = PTR(r);
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exp = EXP(u);
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if (exp <= 0)
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{
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/* u is only a fraction */
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if ((size ^ dir) < 0)
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goto zero;
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rp[0] = 1;
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EXP(r) = 1;
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SIZ(r) = dir;
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return;
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}
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EXP(r) = exp;
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up = PTR(u);
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asize = ABS (size);
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up += asize;
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/* skip fraction part of u */
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asize = MIN (asize, exp);
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/* don't lose precision in the copy */
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prec = PREC (r) + 1;
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/* skip excess over target precision */
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asize = MIN (asize, prec);
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up -= asize;
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if ((size ^ dir) >= 0)
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{
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/* rounding direction matches sign, must increment if ignored part is
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non-zero */
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for (p = PTR(u); p != up; p++)
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{
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if (*p != 0)
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{
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if (mpn_add_1 (rp, up, asize, CNST_LIMB(1)))
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{
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/* was all 0xFF..FFs, which have become zeros, giving just
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a carry */
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rp[0] = 1;
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asize = 1;
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EXP(r)++;
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}
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SIZ(r) = (size >= 0 ? asize : -asize);
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return;
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}
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}
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}
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SIZ(r) = (size >= 0 ? asize : -asize);
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if (rp != up)
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MPN_COPY_INCR (rp, up, asize);
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}
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void
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mpf_ceil (mpf_ptr r, mpf_srcptr u)
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{
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mpf_ceil_or_floor (r, u, 1);
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}
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void
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mpf_floor (mpf_ptr r, mpf_srcptr u)
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{
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mpf_ceil_or_floor (r, u, -1);
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}
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