1/* mpf_ceil, mpf_floor -- round an mpf to an integer.
2
3Copyright 2001, 2004, 2012 Free Software Foundation, Inc.
4
5This file is part of the GNU MP Library.
6
7The GNU MP Library is free software; you can redistribute it and/or modify
8it under the terms of either:
9
10  * the GNU Lesser General Public License as published by the Free
11    Software Foundation; either version 3 of the License, or (at your
12    option) any later version.
13
14or
15
16  * the GNU General Public License as published by the Free Software
17    Foundation; either version 2 of the License, or (at your option) any
18    later version.
19
20or both in parallel, as here.
21
22The GNU MP Library is distributed in the hope that it will be useful, but
23WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
24or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
25for more details.
26
27You should have received copies of the GNU General Public License and the
28GNU Lesser General Public License along with the GNU MP Library.  If not,
29see https://www.gnu.org/licenses/.  */
30
31#include "gmp-impl.h"
32
33
34/* dir==1 for ceil, dir==-1 for floor
35
36   Notice the use of prec+1 ensures mpf_ceil and mpf_floor are equivalent to
37   mpf_set if u is already an integer.  */
38
39static void __gmpf_ceil_or_floor (REGPARM_2_1 (mpf_ptr, mpf_srcptr, int)) REGPARM_ATTR (1);
40#define mpf_ceil_or_floor(r,u,dir)  __gmpf_ceil_or_floor (REGPARM_2_1 (r, u, dir))
41
42REGPARM_ATTR (1) static void
43mpf_ceil_or_floor (mpf_ptr r, mpf_srcptr u, int dir)
44{
45  mp_ptr     rp, up, p;
46  mp_size_t  size, asize, prec;
47  mp_exp_t   exp;
48
49  size = SIZ(u);
50  if (size == 0)
51    {
52    zero:
53      SIZ(r) = 0;
54      EXP(r) = 0;
55      return;
56    }
57
58  rp = PTR(r);
59  exp = EXP(u);
60  if (exp <= 0)
61    {
62      /* u is only a fraction */
63      if ((size ^ dir) < 0)
64        goto zero;
65      rp[0] = 1;
66      EXP(r) = 1;
67      SIZ(r) = dir;
68      return;
69    }
70  EXP(r) = exp;
71
72  up = PTR(u);
73  asize = ABS (size);
74  up += asize;
75
76  /* skip fraction part of u */
77  asize = MIN (asize, exp);
78
79  /* don't lose precision in the copy */
80  prec = PREC (r) + 1;
81
82  /* skip excess over target precision */
83  asize = MIN (asize, prec);
84
85  up -= asize;
86
87  if ((size ^ dir) >= 0)
88    {
89      /* rounding direction matches sign, must increment if ignored part is
90         non-zero */
91      for (p = PTR(u); p != up; p++)
92        {
93          if (*p != 0)
94            {
95              if (mpn_add_1 (rp, up, asize, CNST_LIMB(1)))
96                {
97                  /* was all 0xFF..FFs, which have become zeros, giving just
98                     a carry */
99                  rp[0] = 1;
100                  asize = 1;
101                  EXP(r)++;
102                }
103              SIZ(r) = (size >= 0 ? asize : -asize);
104              return;
105            }
106        }
107    }
108
109  SIZ(r) = (size >= 0 ? asize : -asize);
110  if (rp != up)
111    MPN_COPY_INCR (rp, up, asize);
112}
113
114
115void
116mpf_ceil (mpf_ptr r, mpf_srcptr u)
117{
118  mpf_ceil_or_floor (r, u, 1);
119}
120
121void
122mpf_floor (mpf_ptr r, mpf_srcptr u)
123{
124  mpf_ceil_or_floor (r, u, -1);
125}
126