xref: /illumos-gate/usr/src/boot/libsa/string/strcspn.c (revision 22028508)
1 /*-
2  * Copyright (c) 2005 David Schultz <das@FreeBSD.ORG>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include <sys/types.h>
31 #include <limits.h>
32 #include <string.h>
33 
34 #define	IDX(c)	((u_char)(c) / LONG_BIT)
35 #define	BIT(c)	((u_long)1 << ((u_char)(c) % LONG_BIT))
36 
37 size_t
strcspn(const char * s,const char * charset)38 strcspn(const char *s, const char *charset)
39 {
40 	/*
41 	 * NB: idx and bit are temporaries whose use causes gcc 3.4.2 to
42 	 * generate better code.  Without them, gcc gets a little confused.
43 	 */
44 	const char *s1;
45 	u_long bit;
46 	u_long tbl[(UCHAR_MAX + 1) / LONG_BIT];
47 	int idx;
48 
49 	if(*s == '\0')
50 		return (0);
51 
52 #if LONG_BIT == 64	/* always better to unroll on 64-bit architectures */
53 	tbl[0] = 1;
54 	tbl[3] = tbl[2] = tbl[1] = 0;
55 #else
56 	for (tbl[0] = idx = 1; idx < sizeof(tbl) / sizeof(tbl[0]); idx++)
57 		tbl[idx] = 0;
58 #endif
59 	for (; *charset != '\0'; charset++) {
60 		idx = IDX(*charset);
61 		bit = BIT(*charset);
62 		tbl[idx] |= bit;
63 	}
64 
65 	for(s1 = s; ; s1++) {
66 		idx = IDX(*s1);
67 		bit = BIT(*s1);
68 		if ((tbl[idx] & bit) != 0)
69 			break;
70 	}
71 	return (s1 - s);
72 }
73