1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
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/types.h>
36
37#include <limits.h>
38
39#define	wsize	sizeof(u_long)
40#define	wmask	(wsize - 1)
41
42#ifdef BZERO
43#include <strings.h>
44
45#undef bzero	/* _FORTIFY_SOURCE */
46
47#define	RETURN	return
48#define	VAL	0
49#define	WIDEVAL	0
50
51void
52bzero(void *dst0, size_t length)
53#else
54#include <string.h>
55
56#undef memset	/* _FORTIFY_SOURCE */
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_long 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	 * TODO: This threshold might not be sensible for 64-bit u_long.
87	 * We should benchmark and revisit this decision.
88	 */
89	if (length < 3 * wsize) {
90		while (length != 0) {
91			*dst++ = VAL;
92			--length;
93		}
94		RETURN;
95	}
96
97#ifndef BZERO
98	if ((c = (u_char)c0) != 0) {	/* Fill the word. */
99		c = (c << 8) | c;	/* u_long is 16 bits. */
100#if ULONG_MAX > 0xffff
101		c = (c << 16) | c;	/* u_long is 32 bits. */
102#endif
103#if ULONG_MAX > 0xffffffff
104		c = (c << 32) | c;	/* u_long is 64 bits. */
105#endif
106	}
107#endif
108	/* Align destination by filling in bytes. */
109	if ((t = (long)dst & wmask) != 0) {
110		t = wsize - t;
111		length -= t;
112		do {
113			*dst++ = VAL;
114		} while (--t != 0);
115	}
116
117	/* Fill words.  Length was >= 2*words so we know t >= 1 here. */
118	t = length / wsize;
119	do {
120		*(u_long *)(void *)dst = WIDEVAL;
121		dst += wsize;
122	} while (--t != 0);
123
124	/* Mop up trailing bytes, if any. */
125	t = length & wmask;
126	if (t != 0)
127		do {
128			*dst++ = VAL;
129		} while (--t != 0);
130	RETURN;
131}
132