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