xref: /php-src/ext/bcmath/libbcmath/src/zero.c (revision e56ed6e1)
1 /* zero.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 "bcmath.h"
33 #include <stdbool.h>
34 #include <stddef.h>
35 
36 /* In some places we need to check if the number NUM is zero. */
37 
bc_is_zero_for_scale(bc_num num,size_t scale)38 bool bc_is_zero_for_scale(bc_num num, size_t scale)
39 {
40 	size_t count;
41 	char *nptr;
42 
43 	/* Quick check. */
44 	if (num == BCG(_zero_)) {
45 		return true;
46 	}
47 
48 	/* Initialize */
49 	count = num->n_len + scale;
50 	nptr = num->n_value;
51 
52 	/* The check */
53 	while ((count > 0) && (*nptr++ == 0)) count--;
54 
55 	return count == 0;
56 }
57 
bc_is_zero(bc_num num)58 bool bc_is_zero(bc_num num)
59 {
60 	return bc_is_zero_for_scale(num, num->n_scale);
61 }
62