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 * 4. 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 #include "strings.h"
34 #include <sys/types.h>
35
36 #define wsize sizeof(u_int)
37 #define wmask (wsize - 1)
38
39 // n.b. this must be compiled with -fno-builtin or it might get optimized into
40 // a recursive call to bzero.
41 __attribute__((visibility("hidden")))
42 void
_libkernel_bzero(void * dst0,size_t length)43 _libkernel_bzero(void *dst0, size_t length)
44 {
45 return (void)_libkernel_memset(dst0, 0, length);
46 }
47
48 #define RETURN return (dst0)
49 #define VAL c0
50 #define WIDEVAL c
51
52 __attribute__((visibility("hidden")))
53 void *
_libkernel_memset(void * dst0,int c0,size_t length)54 _libkernel_memset(void *dst0, int c0, size_t length)
55 {
56 size_t t;
57 u_int c;
58 u_char *dst;
59
60 dst = dst0;
61 /*
62 * If not enough words, just fill bytes. A length >= 2 words
63 * guarantees that at least one of them is `complete' after
64 * any necessary alignment. For instance:
65 *
66 * |-----------|-----------|-----------|
67 * |00|01|02|03|04|05|06|07|08|09|0A|00|
68 * ^---------------------^
69 * dst dst+length-1
70 *
71 * but we use a minimum of 3 here since the overhead of the code
72 * to do word writes is substantial.
73 */
74 if (length < 3 * wsize) {
75 while (length != 0) {
76 *dst++ = VAL;
77 --length;
78 }
79 RETURN;
80 }
81
82 if ((c = (u_char)c0) != 0) { /* Fill the word. */
83 c = (c << 8) | c; /* u_int is 16 bits. */
84 #if UINT_MAX > 0xffff
85 c = (c << 16) | c; /* u_int is 32 bits. */
86 #endif
87 #if UINT_MAX > 0xffffffff
88 c = (c << 32) | c; /* u_int is 64 bits. */
89 #endif
90 }
91 /* Align destination by filling in bytes. */
92 if ((t = (long)dst & wmask) != 0) {
93 t = wsize - t;
94 length -= t;
95 do {
96 *dst++ = VAL;
97 } while (--t != 0);
98 }
99
100 /* Fill words. Length was >= 2*words so we know t >= 1 here. */
101 t = length / wsize;
102 do {
103 *(u_int *)dst = WIDEVAL;
104 dst += wsize;
105 } while (--t != 0);
106
107 /* Mop up trailing bytes, if any. */
108 t = length & wmask;
109 if (t != 0) {
110 do {
111 *dst++ = VAL;
112 } while (--t != 0);
113 }
114 RETURN;
115 }
116