bcopy.c revision 1.4
1 /* $NetBSD: bcopy.c,v 1.4 2008/03/25 21:22:37 christos 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 * 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[] = "@(#)bcopy.c 8.1 (Berkeley) 6/4/93"; 39 #else 40 __RCSID("$NetBSD: bcopy.c,v 1.4 2008/03/25 21:22:37 christos Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #if !defined(_KERNEL) && !defined(_STANDALONE) 45 #include <assert.h> 46 #include <string.h> 47 #else 48 #include <lib/libkern/libkern.h> 49 #endif 50 51 #ifdef _FORTIFY_SOURCE 52 #undef bcopy 53 #undef memcpy 54 #undef memmove 55 #endif 56 57 #ifndef __OPTIMIZE_SIZE__ 58 /* 59 * sizeof(word) MUST BE A POWER OF TWO 60 * SO THAT wmask BELOW IS ALL ONES 61 */ 62 typedef long word; /* "word" used for optimal copy speed */ 63 64 #define wsize sizeof(word) 65 #define wmask (wsize - 1) 66 67 /* 68 * Copy a block of memory, handling overlap. 69 * This is the routine that actually implements 70 * (the portable versions of) bcopy, memcpy, and memmove. 71 */ 72 #ifdef MEMCOPY 73 void * 74 memcpy(void *dst0, const void *src0, size_t length) 75 #else 76 #ifdef MEMMOVE 77 void * 78 memmove(void *dst0, const void *src0, size_t length) 79 #else 80 void 81 bcopy(const void *src0, void *dst0, size_t length) 82 #endif 83 #endif 84 { 85 char *dst = dst0; 86 const char *src = src0; 87 size_t t; 88 unsigned long u; 89 90 #if !defined(_KERNEL) 91 _DIAGASSERT(dst0 != 0); 92 _DIAGASSERT(src0 != 0); 93 #endif 94 95 if (length == 0 || dst == src) /* nothing to do */ 96 goto done; 97 98 /* 99 * Macros: loop-t-times; and loop-t-times, t>0 100 */ 101 #define TLOOP(s) if (t) TLOOP1(s) 102 #define TLOOP1(s) do { s; } while (--t) 103 104 if ((unsigned long)dst < (unsigned long)src) { 105 /* 106 * Copy forward. 107 */ 108 u = (unsigned long)src; /* only need low bits */ 109 if ((u | (unsigned long)dst) & wmask) { 110 /* 111 * Try to align operands. This cannot be done 112 * unless the low bits match. 113 */ 114 if ((u ^ (unsigned long)dst) & wmask || length < wsize) 115 t = length; 116 else 117 t = wsize - (size_t)(u & wmask); 118 length -= t; 119 TLOOP1(*dst++ = *src++); 120 } 121 /* 122 * Copy whole words, then mop up any trailing bytes. 123 */ 124 t = length / wsize; 125 TLOOP(*(word *)(void *)dst = *(const word *)(const void *)src; src += wsize; dst += wsize); 126 t = length & wmask; 127 TLOOP(*dst++ = *src++); 128 } else { 129 /* 130 * Copy backwards. Otherwise essentially the same. 131 * Alignment works as before, except that it takes 132 * (t&wmask) bytes to align, not wsize-(t&wmask). 133 */ 134 src += length; 135 dst += length; 136 _DIAGASSERT((unsigned long)dst >= (unsigned long)dst0); 137 _DIAGASSERT((unsigned long)src >= (unsigned long)src0); 138 u = (unsigned long)src; 139 if ((u | (unsigned long)dst) & wmask) { 140 if ((u ^ (unsigned long)dst) & wmask || length <= wsize) 141 t = length; 142 else 143 t = (size_t)(u & wmask); 144 length -= t; 145 TLOOP1(*--dst = *--src); 146 } 147 t = length / wsize; 148 TLOOP(src -= wsize; dst -= wsize; *(word *)(void *)dst = *(const word *)(const void *)src); 149 t = length & wmask; 150 TLOOP(*--dst = *--src); 151 } 152 done: 153 #if defined(MEMCOPY) || defined(MEMMOVE) 154 return (dst0); 155 #else 156 return; 157 #endif 158 } 159 #else 160 #ifdef MEMCOPY 161 /* 162 * This is designed to be small, not fast. 163 */ 164 void * 165 memcpy(void *s1, const void *s2, size_t n) 166 { 167 const char *f = s2; 168 char *t = s1; 169 170 while (n-- > 0) 171 *t++ = *f++; 172 return s1; 173 } 174 #endif 175 #ifdef MEMMOVE 176 /* 177 * This is designed to be small, not fast. 178 */ 179 void * 180 memmove(void *s1, const void *s2, size_t n) 181 { 182 const char *f = s2; 183 char *t = s1; 184 185 if (f < t) { 186 f += n; 187 t += n; 188 while (n-- > 0) 189 *--t = *--f; 190 } else { 191 while (n-- > 0) 192 *t++ = *f++; 193 } 194 return s1; 195 } 196 #endif 197 #endif 198
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