1 /* $NetBSD: bcopy.c,v 1.2 2006/02/05 06:47:48 ross 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 1.2 2006/02/05 06:47:48 ross 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 /* 52 * sizeof(word) MUST BE A POWER OF TWO 53 * SO THAT wmask BELOW IS ALL ONES 54 */ 55 typedef long word; /* "word" used for optimal copy speed */ 56 57 #define wsize sizeof(word) 58 #define wmask (wsize - 1) 59 60 /* 61 * Copy a block of memory, handling overlap. 62 * This is the routine that actually implements 63 * (the portable versions of) bcopy, memcpy, and memmove. 64 */ 65 #ifdef MEMCOPY 66 void * 67 memcpy(dst0, src0, length) 68 #else 69 #ifdef MEMMOVE 70 void * 71 memmove(dst0, src0, length) 72 #else 73 void 74 bcopy(src0, dst0, length) 75 #endif 76 #endif 77 void *dst0; 78 const void *src0; 79 size_t length; 80 { 81 char *dst = dst0; 82 const char *src = src0; 83 size_t t; 84 unsigned long u; 85 86 #if !defined(_KERNEL) 87 _DIAGASSERT(dst0 != 0); 88 _DIAGASSERT(src0 != 0); 89 #endif 90 91 if (length == 0 || dst == src) /* nothing to do */ 92 goto done; 93 94 /* 95 * Macros: loop-t-times; and loop-t-times, t>0 96 */ 97 #define TLOOP(s) if (t) TLOOP1(s) 98 #define TLOOP1(s) do { s; } while (--t) 99 100 if ((unsigned long)dst < (unsigned long)src) { 101 /* 102 * Copy forward. 103 */ 104 u = (unsigned long)src; /* only need low bits */ 105 if ((u | (unsigned long)dst) & wmask) { 106 /* 107 * Try to align operands. This cannot be done 108 * unless the low bits match. 109 */ 110 if ((u ^ (unsigned long)dst) & wmask || length < wsize) 111 t = length; 112 else 113 t = wsize - (size_t)(u & wmask); 114 length -= t; 115 TLOOP1(*dst++ = *src++); 116 } 117 /* 118 * Copy whole words, then mop up any trailing bytes. 119 */ 120 t = length / wsize; 121 TLOOP(*(word *)(void *)dst = *(const word *)(const void *)src; src += wsize; dst += wsize); 122 t = length & wmask; 123 TLOOP(*dst++ = *src++); 124 } else { 125 /* 126 * Copy backwards. Otherwise essentially the same. 127 * Alignment works as before, except that it takes 128 * (t&wmask) bytes to align, not wsize-(t&wmask). 129 */ 130 src += length; 131 dst += length; 132 _DIAGASSERT((unsigned long)dst >= (unsigned long)dst0); 133 _DIAGASSERT((unsigned long)src >= (unsigned long)src0); 134 u = (unsigned long)src; 135 if ((u | (unsigned long)dst) & wmask) { 136 if ((u ^ (unsigned long)dst) & wmask || length <= wsize) 137 t = length; 138 else 139 t = (size_t)(u & wmask); 140 length -= t; 141 TLOOP1(*--dst = *--src); 142 } 143 t = length / wsize; 144 TLOOP(src -= wsize; dst -= wsize; *(word *)(void *)dst = *(const word *)(const void *)src); 145 t = length & wmask; 146 TLOOP(*--dst = *--src); 147 } 148 done: 149 #if defined(MEMCOPY) || defined(MEMMOVE) 150 return (dst0); 151 #else 152 return; 153 #endif 154 } 155