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/cdefs.h>
30#include <sys/libkern.h>
31#include <sys/limits.h>
32#include <sys/types.h>
33
34#define	IDX(c)	((u_char)(c) / LONG_BIT)
35#define	BIT(c)	((u_long)1 << ((u_char)(c) % LONG_BIT))
36
37size_t
38strspn(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[3] = tbl[2] = tbl[1] = tbl[0] = 0;
54#else
55	for (idx = 0; idx < sizeof(tbl) / sizeof(tbl[0]); idx++)
56		tbl[idx] = 0;
57#endif
58	for (; *charset != '\0'; charset++) {
59		idx = IDX(*charset);
60		bit = BIT(*charset);
61		tbl[idx] |= bit;
62	}
63
64	for(s1 = s; ; s1++) {
65		idx = IDX(*s1);
66		bit = BIT(*s1);
67		if ((tbl[idx] & bit) == 0)
68			break;
69	}
70	return (s1 - s);
71}
72