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libc: Use musl's optimized memchr

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Parentheses added to HASZERO macro to avoid a GCC warning.

Reviewed by:	kib, mjg
Obtained from:	musl (snapshot at commit 4d0a82170a)
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D17631
This commit is contained in:
Ed Maste 2019-09-02 13:56:44 +00:00
parent ebea9e6d8f
commit 6b62f42434
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=351700
1 changed files with 40 additions and 41 deletions
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81
lib/libc/string/memchr.c
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@ -1,55 +1,54 @@
/*-
* SPDX-License-Identifier: BSD-3-Clause
* SPDX-License-Identifier: MIT
*
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
* Copyright (c) 2005-2014 Rich Felker, et al.
*
* This code is derived from software contributed to Berkeley by
* Chris Torek.
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* 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.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)memchr.c 8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <string.h>
#include <stdint.h>
#include <limits.h>
void *
memchr(const void *s, int c, size_t n)
#define SS (sizeof(size_t))
#define ALIGN (sizeof(size_t)-1)
#define ONES ((size_t)-1/UCHAR_MAX)
#define HIGHS (ONES * (UCHAR_MAX/2+1))
#define HASZERO(x) (((x)-ONES) & ~(x) & HIGHS)
void *memchr(const void *src, int c, size_t n)
{
if (n != 0) {
const unsigned char *p = s;
do {
if (*p++ == (unsigned char)c)
return ((void *)(p - 1));
} while (--n != 0);
const unsigned char *s = src;
c = (unsigned char)c;
#ifdef __GNUC__
for (; ((uintptr_t)s & ALIGN) && n && *s != c; s++, n--);
if (n && *s != c) {
typedef size_t __attribute__((__may_alias__)) word;
const word *w;
size_t k = ONES * c;
for (w = (const void *)s; n>=SS && !HASZERO(*w^k); w++, n-=SS);
s = (const void *)w;
}
return (NULL);
#endif
for (; n && *s != c; s++, n--);
return n ? (void *)s : 0;
}