NetBSD/lib/libc/string/memset.c

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/* $NetBSD: memset.c,v 1.14 1999/09/20 04:39:45 lukem Exp $ */
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/*-
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* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
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*
* This code is derived from software contributed to Berkeley by
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* Mike Hibler and Chris Torek.
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*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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.
*
* 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.
*/
#include <sys/cdefs.h>
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#if defined(LIBC_SCCS) && !defined(lint)
#if 0
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static char sccsid[] = "@(#)memset.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: memset.c,v 1.14 1999/09/20 04:39:45 lukem Exp $");
#endif
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#endif /* LIBC_SCCS and not lint */
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#include <sys/types.h>
#if !defined(_KERNEL) && !defined(_STANDALONE)
#include <assert.h>
#include <limits.h>
#include <string.h>
#else
#include <lib/libkern/libkern.h>
#include <machine/limits.h>
#define _DIAGASSERT(x) (void)0
#endif
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#define wsize sizeof(u_int)
#define wmask (wsize - 1)
#ifdef BZERO
#define RETURN return
#define VAL 0
#define WIDEVAL 0
void
bzero(dst0, length)
void *dst0;
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size_t length;
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#else
#define RETURN return (dst0)
#define VAL c0
#define WIDEVAL c
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void *
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memset(dst0, c0, length)
void *dst0;
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int c0;
size_t length;
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#endif
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{
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size_t t;
#ifndef BZERO
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u_int c;
#endif
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u_char *dst;
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_DIAGASSERT(dst0 != 0);
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dst = dst0;
/*
* If not enough words, just fill bytes. A length >= 2 words
* guarantees that at least one of them is `complete' after
* any necessary alignment. For instance:
*
* |-----------|-----------|-----------|
* |00|01|02|03|04|05|06|07|08|09|0A|00|
* ^---------------------^
* dst dst+length-1
*
* but we use a minimum of 3 here since the overhead of the code
* to do word writes is substantial.
*/
if (length < 3 * wsize) {
while (length != 0) {
*dst++ = VAL;
--length;
}
RETURN;
}
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#ifndef BZERO
if ((c = (u_char)c0) != 0) { /* Fill the word. */
c = (c << 8) | c; /* u_int is 16 bits. */
#if UINT_MAX > 0xffff
c = (c << 16) | c; /* u_int is 32 bits. */
#endif
#if UINT_MAX > 0xffffffff
c = (c << 32) | c; /* u_int is 64 bits. */
#endif
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}
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#endif
/* Align destination by filling in bytes. */
if ((t = (u_long)dst & wmask) != 0) {
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t = wsize - t;
length -= t;
do {
*dst++ = VAL;
} while (--t != 0);
}
/* Fill words. Length was >= 2*words so we know t >= 1 here. */
t = length / wsize;
do {
*(u_int *)dst = WIDEVAL;
dst += wsize;
} while (--t != 0);
/* Mop up trailing bytes, if any. */
t = length & wmask;
if (t != 0)
do {
*dst++ = VAL;
} while (--t != 0);
RETURN;
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}