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memset.c revision 1.4 
      1 /*	$NetBSD: memset.c,v 1.4 2008/03/26 06:19:36 apb Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1990, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Mike Hibler and Chris Torek.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. Neither the name of the University nor the names of its contributors
     19  *    may be used to endorse or promote products derived from this software
     20  *    without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  */
     34 
     35 #include <sys/cdefs.h>
     36 #if defined(LIBC_SCCS) && !defined(lint)
     37 #if 0
     38 static char sccsid[] = "@(#)memset.c	8.1 (Berkeley) 6/4/93";
     39 #else
     40 __RCSID("$NetBSD: memset.c,v 1.4 2008/03/26 06:19:36 apb Exp $");
     41 #endif
     42 #endif /* LIBC_SCCS and not lint */
     43 
     44 #include <sys/types.h>
     45 
     46 #if !defined(_KERNEL) && !defined(_STANDALONE)
     47 #include <assert.h>
     48 #include <limits.h>
     49 #include <string.h>
     50 #else
     51 #include <lib/libkern/libkern.h>
     52 #include <machine/limits.h>
     53 #endif
     54 
     55 #define	wsize	sizeof(u_int)
     56 #define	wmask	(wsize - 1)
     57 
     58 #ifdef _FORTIFY_SOURCE
     59 #undef bzero
     60 #undef memset
     61 #endif
     62 
     63 #ifndef __OPTIMIZE_SIZE__
     64 #ifdef BZERO
     65 #define	RETURN	return
     66 #define	VAL	0
     67 #define	WIDEVAL	0
     68 
     69 void
     70 bzero(void *dst0, size_t length)
     71 #else
     72 #define	RETURN	return (dst0)
     73 #define	VAL	c0
     74 #define	WIDEVAL	c
     75 
     76 void *
     77 memset(void *dst0, int c0, size_t length)
     78 #endif
     79 {
     80 	size_t t;
     81 #ifndef BZERO
     82 	u_int c;
     83 #endif
     84 	u_char *dst;
     85 
     86 	_DIAGASSERT(dst0 != 0);
     87 
     88 	dst = dst0;
     89 	/*
     90 	 * If not enough words, just fill bytes.  A length >= 2 words
     91 	 * guarantees that at least one of them is `complete' after
     92 	 * any necessary alignment.  For instance:
     93 	 *
     94 	 *	|-----------|-----------|-----------|
     95 	 *	|00|01|02|03|04|05|06|07|08|09|0A|00|
     96 	 *	          ^---------------------^
     97 	 *		 dst		 dst+length-1
     98 	 *
     99 	 * but we use a minimum of 3 here since the overhead of the code
    100 	 * to do word writes is substantial.
    101 	 */
    102 	if (length < 3 * wsize) {
    103 		while (length != 0) {
    104 			*dst++ = VAL;
    105 			--length;
    106 		}
    107 		RETURN;
    108 	}
    109 
    110 #ifndef BZERO
    111 	if ((c = (u_char)c0) != 0) {	/* Fill the word. */
    112 		c = (c << 8) | c;	/* u_int is 16 bits. */
    113 #if UINT_MAX > 0xffff
    114 		c = (c << 16) | c;	/* u_int is 32 bits. */
    115 #endif
    116 #if UINT_MAX > 0xffffffff
    117 		c = (c << 32) | c;	/* u_int is 64 bits. */
    118 #endif
    119 	}
    120 #endif
    121 	/* Align destination by filling in bytes. */
    122 	if ((t = (size_t)((u_long)dst & wmask)) != 0) {
    123 		t = wsize - t;
    124 		length -= t;
    125 		do {
    126 			*dst++ = VAL;
    127 		} while (--t != 0);
    128 	}
    129 
    130 	/* Fill words.  Length was >= 2*words so we know t >= 1 here. */
    131 	t = length / wsize;
    132 	do {
    133 		*(u_int *)(void *)dst = WIDEVAL;
    134 		dst += wsize;
    135 	} while (--t != 0);
    136 
    137 	/* Mop up trailing bytes, if any. */
    138 	t = length & wmask;
    139 	if (t != 0)
    140 		do {
    141 			*dst++ = VAL;
    142 		} while (--t != 0);
    143 	RETURN;
    144 }
    145 #else /* __OPTIMIZE_SIZE__ */
    146 #ifdef BZERO
    147 void
    148 bzero(void *dstv, size_t length)
    149 {
    150 	u_char *dst = dstv;
    151 	while (length-- > 0)
    152 		*dst++ = 0;
    153 }
    154 #endif
    155 #ifdef MEMSET
    156 void *
    157 memset(void *dstv, int c, size_t length)
    158 {
    159 	u_char *dst = dstv;
    160 	while (length-- > 0)
    161 		*dst++ = c;
    162 	return *dst;
    163 }
    164 #endif
    165 #endif /* __OPTIMIZE_SIZE__ */
    166