xref: /PHP-8.1/ext/bcmath/libbcmath/src/nearzero.c (revision eb9ad31b)
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 <config.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <ctype.h>
36 #include <stdarg.h>
37 #include "bcmath.h"
38 #include "private.h"
39 
40 /* In some places we need to check if the number NUM is almost zero.
41    Specifically, all but the last digit is 0 and the last digit is 1.
42    Last digit is defined by scale. */
43 
44 char
bc_is_near_zero(num,scale)45 bc_is_near_zero (num, scale)
46      bc_num num;
47      int scale;
48 {
49   int  count;
50   char *nptr;
51 
52   /* Error checking */
53   if (scale > num->n_scale)
54     scale = num->n_scale;
55 
56   /* Initialize */
57   count = num->n_len + scale;
58   nptr = num->n_value;
59 
60   /* The check */
61   while ((count > 0) && (*nptr++ == 0)) count--;
62 
63   if (count != 0 && (count != 1 || *--nptr != 1))
64     return FALSE;
65   else
66     return TRUE;
67 }
68