xref: /titanic_50/usr/src/lib/libc/port/gen/atoi.c (revision 7257d1b4d25bfac0c802847390e98a464fd787ac)
1  /*
2   * CDDL HEADER START
3   *
4   * The contents of this file are subject to the terms of the
5   * Common Development and Distribution License (the "License").
6   * You may not use this file except in compliance with the License.
7   *
8   * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9   * or http://www.opensolaris.org/os/licensing.
10   * See the License for the specific language governing permissions
11   * and limitations under the License.
12   *
13   * When distributing Covered Code, include this CDDL HEADER in each
14   * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15   * If applicable, add the following below this CDDL HEADER, with the
16   * fields enclosed by brackets "[]" replaced with your own identifying
17   * information: Portions Copyright [yyyy] [name of copyright owner]
18   *
19   * CDDL HEADER END
20   */
21  
22  /*
23   * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24   * Use is subject to license terms.
25   */
26  
27  /*	Copyright (c) 1988 AT&T	*/
28  /*	  All Rights Reserved  	*/
29  
30  #pragma ident	"%Z%%M%	%I%	%E% SMI"
31  
32  #include "lint.h"
33  #include <ctype.h>
34  #include <sys/types.h>
35  #include <stdlib.h>
36  
37  #define	ATOI
38  
39  #ifdef	ATOI
40  typedef int TYPE;
41  #define	NAME	atoi
42  #else
43  typedef long TYPE;
44  #define	NAME	atol
45  #endif
46  
47  TYPE
NAME(const char * p)48  NAME(const char *p)
49  {
50  	TYPE n;
51  	int c, neg = 0;
52  	unsigned char	*up = (unsigned char *)p;
53  
54  	if (!isdigit(c = *up)) {
55  		while (isspace(c))
56  			c = *++up;
57  		switch (c) {
58  		case '-':
59  			neg++;
60  			/* FALLTHROUGH */
61  		case '+':
62  			c = *++up;
63  		}
64  		if (!isdigit(c))
65  			return (0);
66  	}
67  	for (n = '0' - c; isdigit(c = *++up); ) {
68  		n *= 10; /* two steps to avoid unnecessary overflow */
69  		n += '0' - c; /* accum neg to avoid surprises at MAX */
70  	}
71  	return (neg ? n : -n);
72  }
73