FreeBSD/Linux Kernel Cross Reference
sys/libkern/strcspn.c
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: src/sys/libkern/strcspn.c,v 1.1 2008/08/15 04:07:22 kmacy Exp $");
29
30 #include <sys/libkern.h>
31 #include <sys/types.h>
32 #include <sys/limits.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
38 strcspn(const char * __restrict s, const char * __restrict 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
|