1 /* $NetBSD: bcopy.c,v 1.3 2007/06/04 18:19:27 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 1.3 2007/06/04 18:19:27 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 /* 58 * sizeof(word) MUST BE A POWER OF TWO 59 * SO THAT wmask BELOW IS ALL ONES 60 */ 61 typedef long word; /* "word" used for optimal copy speed */ 62 63 #define wsize sizeof(word) 64 #define wmask (wsize - 1) 65 66 /* 67 * Copy a block of memory, handling overlap. 68 * This is the routine that actually implements 69 * (the portable versions of) bcopy, memcpy, and memmove. 70 */ 71 #ifdef MEMCOPY 72 void * 73 memcpy(void *dst0, const void *src0, size_t length) 74 #else 75 #ifdef MEMMOVE 76 void * 77 memmove(void *dst0, const void *src0, size_t length) 78 #else 79 void 80 bcopy(const void *src0, void *dst0, size_t length) 81 #endif 82 #endif 83 { 84 char *dst = dst0; 85 const char *src = src0; 86 size_t t; 87 unsigned long u; 88 89 #if !defined(_KERNEL) 90 _DIAGASSERT(dst0 != 0); 91 _DIAGASSERT(src0 != 0); 92 #endif 93 94 if (length == 0 || dst == src) /* nothing to do */ 95 goto done; 96 97 /* 98 * Macros: loop-t-times; and loop-t-times, t>0 99 */ 100 #define TLOOP(s) if (t) TLOOP1(s) 101 #define TLOOP1(s) do { s; } while (--t) 102 103 if ((unsigned long)dst < (unsigned long)src) { 104 /* 105 * Copy forward. 106 */ 107 u = (unsigned long)src; /* only need low bits */ 108 if ((u | (unsigned long)dst) & wmask) { 109 /* 110 * Try to align operands. This cannot be done 111 * unless the low bits match. 112 */ 113 if ((u ^ (unsigned long)dst) & wmask || length < wsize) 114 t = length; 115 else 116 t = wsize - (size_t)(u & wmask); 117 length -= t; 118 TLOOP1(*dst++ = *src++); 119 } 120 /* 121 * Copy whole words, then mop up any trailing bytes. 122 */ 123 t = length / wsize; 124 TLOOP(*(word *)(void *)dst = *(const word *)(const void *)src; src += wsize; dst += wsize); 125 t = length & wmask; 126 TLOOP(*dst++ = *src++); 127 } else { 128 /* 129 * Copy backwards. Otherwise essentially the same. 130 * Alignment works as before, except that it takes 131 * (t&wmask) bytes to align, not wsize-(t&wmask). 132 */ 133 src += length; 134 dst += length; 135 _DIAGASSERT((unsigned long)dst >= (unsigned long)dst0); 136 _DIAGASSERT((unsigned long)src >= (unsigned long)src0); 137 u = (unsigned long)src; 138 if ((u | (unsigned long)dst) & wmask) { 139 if ((u ^ (unsigned long)dst) & wmask || length <= wsize) 140 t = length; 141 else 142 t = (size_t)(u & wmask); 143 length -= t; 144 TLOOP1(*--dst = *--src); 145 } 146 t = length / wsize; 147 TLOOP(src -= wsize; dst -= wsize; *(word *)(void *)dst = *(const word *)(const void *)src); 148 t = length & wmask; 149 TLOOP(*--dst = *--src); 150 } 151 done: 152 #if defined(MEMCOPY) || defined(MEMMOVE) 153 return (dst0); 154 #else 155 return; 156 #endif 157 } 158