1 /* nearzero.c: bcmath library file. */
2 /*
3 Copyright (C) 1991, 1992, 1993, 1994, 1997 Free Software Foundation, Inc.
4 Copyright (C) 2000 Philip A. Nelson
5
6 This library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2 of the License, or (at your option) any later version.
10
11 This library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details. (LICENSE)
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with this library; if not, write to:
18
19 The Free Software Foundation, Inc.
20 59 Temple Place, Suite 330
21 Boston, MA 02111-1307 USA.
22
23 You may contact the author by:
24 e-mail: philnelson@acm.org
25 us-mail: Philip A. Nelson
26 Computer Science Department, 9062
27 Western Washington University
28 Bellingham, WA 98226-9062
29
30 *************************************************************************/
31
32 #include <stdbool.h>
33 #include "bcmath.h"
34 #include <stddef.h>
35
36 /* In some places we need to check if the number NUM is almost zero.
37 Specifically, all but the last digit is 0 and the last digit is 1.
38 Last digit is defined by scale. */
39
bc_is_near_zero(bc_num num,size_t scale)40 bool bc_is_near_zero(bc_num num, size_t scale)
41 {
42 /* Error checking */
43 if (scale > num->n_scale) {
44 scale = num->n_scale;
45 }
46
47 /* Initialize */
48 size_t count = num->n_len + scale;
49 const char *nptr = num->n_value;
50
51 /* The check */
52 while ((count > 0) && (*nptr++ == 0)) {
53 count--;
54 }
55
56 return count == 0 || (count == 1 && *--nptr == 1);
57 }
58
