1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
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/types.h>
30 #include <limits.h>
31 #include <string.h>
32
33 #define IDX(c) ((u_char)(c) / LONG_BIT)
34 #define BIT(c) ((u_long)1 << ((u_char)(c) % LONG_BIT))
35
36 size_t
strspn(const char * s,const char * charset)37 strspn(const char *s, const char *charset)
38 {
39 /*
40 * NB: idx and bit are temporaries whose use causes gcc 3.4.2 to
41 * generate better code. Without them, gcc gets a little confused.
42 */
43 const char *s1;
44 u_long bit;
45 u_long tbl[(UCHAR_MAX + 1) / LONG_BIT];
46 int idx;
47
48 if(*s == '\0')
49 return (0);
50
51 #if LONG_BIT == 64 /* always better to unroll on 64-bit architectures */
52 tbl[3] = tbl[2] = tbl[1] = tbl[0] = 0;
53 #else
54 for (idx = 0; idx < sizeof(tbl) / sizeof(tbl[0]); idx++)
55 tbl[idx] = 0;
56 #endif
57 for (; *charset != '\0'; charset++) {
58 idx = IDX(*charset);
59 bit = BIT(*charset);
60 tbl[idx] |= bit;
61 }
62
63 for(s1 = s; ; s1++) {
64 idx = IDX(*s1);
65 bit = BIT(*s1);
66 if ((tbl[idx] & bit) == 0)
67 break;
68 }
69 return (s1 - s);
70 }
71