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