1/*	$NetBSD: memset.c,v 1.1.1.2 2008/05/18 14:29:38 aymeric 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. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *	This product includes software developed by the University of
21 *	California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 *    may be used to endorse or promote products derived from this software
24 *    without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 */
38
39#include "config.h"
40
41#if defined(LIBC_SCCS) && !defined(lint)
42static const char sccsid[] = "@(#)memset.c	8.1 (Berkeley) 6/4/93";
43#endif /* LIBC_SCCS and not lint */
44
45#include <sys/types.h>
46
47#include <limits.h>
48#include <string.h>
49
50/*
51 * PUBLIC: #ifndef HAVE_MEMSET
52 * PUBLIC: void *memset __P((void *, int, size_t));
53 * PUBLIC: #endif
54 */
55#define	wsize	sizeof(u_int)
56#define	wmask	(wsize - 1)
57
58#ifdef BZERO
59#define	RETURN	return
60#define	VAL	0
61#define	WIDEVAL	0
62
63void
64bzero(dst0, length)
65	void *dst0;
66	register size_t length;
67#else
68#define	RETURN	return (dst0)
69#define	VAL	c0
70#define	WIDEVAL	c
71
72void *
73memset(void *dst0, register int c0, register size_t length)
74
75
76
77#endif
78{
79	register size_t t;
80	register u_int c;
81	register u_char *dst;
82
83	dst = dst0;
84	/*
85	 * If not enough words, just fill bytes.  A length >= 2 words
86	 * guarantees that at least one of them is `complete' after
87	 * any necessary alignment.  For instance:
88	 *
89	 *	|-----------|-----------|-----------|
90	 *	|00|01|02|03|04|05|06|07|08|09|0A|00|
91	 *	          ^---------------------^
92	 *		 dst		 dst+length-1
93	 *
94	 * but we use a minimum of 3 here since the overhead of the code
95	 * to do word writes is substantial.
96	 */
97	if (length < 3 * wsize) {
98		while (length != 0) {
99			*dst++ = VAL;
100			--length;
101		}
102		RETURN;
103	}
104
105#ifndef BZERO
106	if ((c = (u_char)c0) != 0) {	/* Fill the word. */
107		c = (c << 8) | c;	/* u_int is 16 bits. */
108#if UINT_MAX > 0xffff
109		c = (c << 16) | c;	/* u_int is 32 bits. */
110#endif
111#if UINT_MAX > 0xffffffff
112		c = (c << 32) | c;	/* u_int is 64 bits. */
113#endif
114	}
115#endif
116	/* Align destination by filling in bytes. */
117	if ((t = (int)dst & wmask) != 0) {
118		t = wsize - t;
119		length -= t;
120		do {
121			*dst++ = VAL;
122		} while (--t != 0);
123	}
124
125	/* Fill words.  Length was >= 2*words so we know t >= 1 here. */
126	t = length / wsize;
127	do {
128		*(u_int *)dst = WIDEVAL;
129		dst += wsize;
130	} while (--t != 0);
131
132	/* Mop up trailing bytes, if any. */
133	t = length & wmask;
134	if (t != 0)
135		do {
136			*dst++ = VAL;
137		} while (--t != 0);
138	RETURN;
139}
140