NetBSD/lib/libc/string/strpbrk.c
joerg 2ca83a6a31 Replace O(nm) versions of strspn, strcspn and strpbrk with O(n+m)
implementations based on the suggestions I made for DragonFly's libc
ages ago. For charset with more than one entry and iterating over the
first two characters of s, this is consistently faster on amd64.
2008-02-22 13:32:19 +00:00

56 lines
1.9 KiB
C

/* $NetBSD: strpbrk.c,v 1.13 2008/02/22 13:32:19 joerg Exp $ */
/*-
* Copyright (c) 2008 Joerg Sonnenberger
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: strpbrk.c,v 1.13 2008/02/22 13:32:19 joerg Exp $");
#include <assert.h>
#include <inttypes.h>
#include <limits.h>
#include <string.h>
char *
strpbrk(const char *s, const char *charset)
{
static const size_t idx[8] = { 1, 2, 4, 8, 16, 32, 64, 128 };
uint8_t set[32];
_DIAGASSERT(s != NULL);
_DIAGASSERT(charset != NULL);
memset(set, 0, sizeof(set));
for (; *charset != '\0'; ++charset)
set[*charset >> 3] |= idx[*charset & 7];
for (; *s != '\0'; ++s) {
if (set[*s >> 3] & idx[*s & 7])
return __UNCONST(s);
}
return NULL;
}