Home | History | Annotate | Line # | Download | only in string
memset.c revision 1.6.10.1 
      1 /*	$NetBSD: memset.c,v 1.6.10.1 2009/05/13 17:23:17 jym 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 1.6.10.1 2009/05/13 17:23:17 jym 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 #if defined(BZERO) && defined(_STANDALONE)
     53 #include <lib/libsa/stand.h>
     54 #endif
     55 #include <machine/limits.h>
     56 #endif
     57 
     58 #define	wsize	sizeof(u_int)
     59 #define	wmask	(wsize - 1)
     60 
     61 #ifdef _FORTIFY_SOURCE
     62 #undef bzero
     63 #undef memset
     64 #endif
     65 
     66 #ifndef __OPTIMIZE_SIZE__
     67 #ifdef BZERO
     68 #define	RETURN	return
     69 #define	VAL	0
     70 #define	WIDEVAL	0
     71 
     72 void
     73 bzero(void *dst0, size_t length)
     74 #else
     75 #define	RETURN	return (dst0)
     76 #define	VAL	c0
     77 #define	WIDEVAL	c
     78 
     79 void *
     80 memset(void *dst0, int c0, size_t length)
     81 #endif
     82 {
     83 	size_t t;
     84 #ifndef BZERO
     85 	u_int c;
     86 #endif
     87 	u_char *dst;
     88 
     89 	_DIAGASSERT(dst0 != 0);
     90 
     91 	dst = dst0;
     92 	/*
     93 	 * If not enough words, just fill bytes.  A length >= 2 words
     94 	 * guarantees that at least one of them is `complete' after
     95 	 * any necessary alignment.  For instance:
     96 	 *
     97 	 *	|-----------|-----------|-----------|
     98 	 *	|00|01|02|03|04|05|06|07|08|09|0A|00|
     99 	 *	          ^---------------------^
    100 	 *		 dst		 dst+length-1
    101 	 *
    102 	 * but we use a minimum of 3 here since the overhead of the code
    103 	 * to do word writes is substantial.
    104 	 */
    105 	if (length < 3 * wsize) {
    106 		while (length != 0) {
    107 			*dst++ = VAL;
    108 			--length;
    109 		}
    110 		RETURN;
    111 	}
    112 
    113 #ifndef BZERO
    114 	if ((c = (u_char)c0) != 0) {	/* Fill the word. */
    115 		c = (c << 8) | c;	/* u_int is 16 bits. */
    116 #if UINT_MAX > 0xffff
    117 		c = (c << 16) | c;	/* u_int is 32 bits. */
    118 #endif
    119 #if UINT_MAX > 0xffffffff
    120 		c = (c << 32) | c;	/* u_int is 64 bits. */
    121 #endif
    122 	}
    123 #endif
    124 	/* Align destination by filling in bytes. */
    125 	if ((t = (size_t)((u_long)dst & wmask)) != 0) {
    126 		t = wsize - t;
    127 		length -= t;
    128 		do {
    129 			*dst++ = VAL;
    130 		} while (--t != 0);
    131 	}
    132 
    133 	/* Fill words.  Length was >= 2*words so we know t >= 1 here. */
    134 	t = length / wsize;
    135 	do {
    136 		*(u_int *)(void *)dst = WIDEVAL;
    137 		dst += wsize;
    138 	} while (--t != 0);
    139 
    140 	/* Mop up trailing bytes, if any. */
    141 	t = length & wmask;
    142 	if (t != 0)
    143 		do {
    144 			*dst++ = VAL;
    145 		} while (--t != 0);
    146 	RETURN;
    147 }
    148 #else /* __OPTIMIZE_SIZE__ */
    149 #ifdef BZERO
    150 void
    151 bzero(void *dstv, size_t length)
    152 {
    153 	u_char *dst = dstv;
    154 	while (length-- > 0)
    155 		*dst++ = 0;
    156 }
    157 #else
    158 void *
    159 memset(void *dstv, int c, size_t length)
    160 {
    161 	u_char *dst = dstv;
    162 	while (length-- > 0)
    163 		*dst++ = c;
    164 	return dstv;
    165 }
    166 #endif /* BZERO */
    167 #endif /* __OPTIMIZE_SIZE__ */
    168