xref: /PHP-7.3/ext/bcmath/libbcmath/src/nearzero.c (revision 1c850bfc)
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.  (COPYING.LIB)
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 <assert.h>
35 #include <stdlib.h>
36 #include <ctype.h>
37 #include <stdarg.h>
38 #include "bcmath.h"
39 #include "private.h"
40 
41 /* In some places we need to check if the number NUM is almost zero.
42    Specifically, all but the last digit is 0 and the last digit is 1.
43    Last digit is defined by scale. */
44 
45 char
bc_is_near_zero(num,scale)46 bc_is_near_zero (num, scale)
47      bc_num num;
48      int scale;
49 {
50   int  count;
51   char *nptr;
52 
53   /* Error checking */
54   if (scale > num->n_scale)
55     scale = num->n_scale;
56 
57   /* Initialize */
58   count = num->n_len + scale;
59   nptr = num->n_value;
60 
61   /* The check */
62   while ((count > 0) && (*nptr++ == 0)) count--;
63 
64   if (count != 0 && (count != 1 || *--nptr != 1))
65     return FALSE;
66   else
67     return TRUE;
68 }
69