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