xref: /titanic_51/usr/src/boot/lib/libc/string/strspn.c (revision 4a5d661a82b942b6538acd26209d959ce98b593a)
1*4a5d661aSToomas Soome /*-
2*4a5d661aSToomas Soome  * Copyright (c) 2005 David Schultz <das@FreeBSD.ORG>
3*4a5d661aSToomas Soome  * All rights reserved.
4*4a5d661aSToomas Soome  *
5*4a5d661aSToomas Soome  * Redistribution and use in source and binary forms, with or without
6*4a5d661aSToomas Soome  * modification, are permitted provided that the following conditions
7*4a5d661aSToomas Soome  * are met:
8*4a5d661aSToomas Soome  * 1. Redistributions of source code must retain the above copyright
9*4a5d661aSToomas Soome  *    notice, this list of conditions and the following disclaimer.
10*4a5d661aSToomas Soome  * 2. Redistributions in binary form must reproduce the above copyright
11*4a5d661aSToomas Soome  *    notice, this list of conditions and the following disclaimer in the
12*4a5d661aSToomas Soome  *    documentation and/or other materials provided with the distribution.
13*4a5d661aSToomas Soome  *
14*4a5d661aSToomas Soome  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15*4a5d661aSToomas Soome  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16*4a5d661aSToomas Soome  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17*4a5d661aSToomas Soome  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18*4a5d661aSToomas Soome  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19*4a5d661aSToomas Soome  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20*4a5d661aSToomas Soome  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21*4a5d661aSToomas Soome  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22*4a5d661aSToomas Soome  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23*4a5d661aSToomas Soome  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24*4a5d661aSToomas Soome  * SUCH DAMAGE.
25*4a5d661aSToomas Soome  */
26*4a5d661aSToomas Soome 
27*4a5d661aSToomas Soome #include <sys/cdefs.h>
28*4a5d661aSToomas Soome __FBSDID("$FreeBSD$");
29*4a5d661aSToomas Soome 
30*4a5d661aSToomas Soome #include <sys/types.h>
31*4a5d661aSToomas Soome #include <limits.h>
32*4a5d661aSToomas Soome #include <string.h>
33*4a5d661aSToomas Soome 
34*4a5d661aSToomas Soome #define	IDX(c)	((u_char)(c) / LONG_BIT)
35*4a5d661aSToomas Soome #define	BIT(c)	((u_long)1 << ((u_char)(c) % LONG_BIT))
36*4a5d661aSToomas Soome 
37*4a5d661aSToomas Soome size_t
38*4a5d661aSToomas Soome strspn(const char *s, const char *charset)
39*4a5d661aSToomas Soome {
40*4a5d661aSToomas Soome 	/*
41*4a5d661aSToomas Soome 	 * NB: idx and bit are temporaries whose use causes gcc 3.4.2 to
42*4a5d661aSToomas Soome 	 * generate better code.  Without them, gcc gets a little confused.
43*4a5d661aSToomas Soome 	 */
44*4a5d661aSToomas Soome 	const char *s1;
45*4a5d661aSToomas Soome 	u_long bit;
46*4a5d661aSToomas Soome 	u_long tbl[(UCHAR_MAX + 1) / LONG_BIT];
47*4a5d661aSToomas Soome 	int idx;
48*4a5d661aSToomas Soome 
49*4a5d661aSToomas Soome 	if(*s == '\0')
50*4a5d661aSToomas Soome 		return (0);
51*4a5d661aSToomas Soome 
52*4a5d661aSToomas Soome #if LONG_BIT == 64	/* always better to unroll on 64-bit architectures */
53*4a5d661aSToomas Soome 	tbl[3] = tbl[2] = tbl[1] = tbl[0] = 0;
54*4a5d661aSToomas Soome #else
55*4a5d661aSToomas Soome 	for (idx = 0; idx < sizeof(tbl) / sizeof(tbl[0]); idx++)
56*4a5d661aSToomas Soome 		tbl[idx] = 0;
57*4a5d661aSToomas Soome #endif
58*4a5d661aSToomas Soome 	for (; *charset != '\0'; charset++) {
59*4a5d661aSToomas Soome 		idx = IDX(*charset);
60*4a5d661aSToomas Soome 		bit = BIT(*charset);
61*4a5d661aSToomas Soome 		tbl[idx] |= bit;
62*4a5d661aSToomas Soome 	}
63*4a5d661aSToomas Soome 
64*4a5d661aSToomas Soome 	for(s1 = s; ; s1++) {
65*4a5d661aSToomas Soome 		idx = IDX(*s1);
66*4a5d661aSToomas Soome 		bit = BIT(*s1);
67*4a5d661aSToomas Soome 		if ((tbl[idx] & bit) == 0)
68*4a5d661aSToomas Soome 			break;
69*4a5d661aSToomas Soome 	}
70*4a5d661aSToomas Soome 	return (s1 - s);
71*4a5d661aSToomas Soome }
72