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 * 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 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)bcopy.c 8.1 (Berkeley) 6/4/93 37 * $FreeBSD: src/lib/libc/string/bcopy.c,v 1.1.1.1.14.1 2001/07/09 23:30:03 obrien Exp $ 38 * $DragonFly: src/lib/libc/string/bcopy.c,v 1.3 2004/10/25 19:38:02 drhodus Exp $ 39 */ 40 41 #include <sys/cdefs.h> 42 #include <string.h> 43 44 /* 45 * sizeof(word) MUST BE A POWER OF TWO 46 * SO THAT wmask BELOW IS ALL ONES 47 */ 48 typedef int word; /* "word" used for optimal copy speed */ 49 50 #define wsize sizeof(word) 51 #define wmask (wsize - 1) 52 53 /* 54 * Copy a block of memory, handling overlap. 55 * This is the routine that actually implements 56 * (the portable versions of) bcopy, memcpy, and memmove. 57 */ 58 #ifdef MEMCOPY 59 void * 60 memcpy(dst0, src0, length) 61 #else 62 #ifdef MEMMOVE 63 void * 64 memmove(dst0, src0, length) 65 #else 66 void 67 bcopy(src0, dst0, length) 68 #endif 69 #endif 70 void *dst0; 71 const void *src0; 72 size_t length; 73 { 74 char *dst = dst0; 75 const char *src = src0; 76 size_t t; 77 78 if (length == 0 || dst == src) /* nothing to do */ 79 goto done; 80 81 /* 82 * Macros: loop-t-times; and loop-t-times, t>0 83 */ 84 #define TLOOP(s) if (t) TLOOP1(s) 85 #define TLOOP1(s) do { s; } while (--t) 86 87 if ((unsigned long)dst < (unsigned long)src) { 88 /* 89 * Copy forward. 90 */ 91 t = (int)src; /* only need low bits */ 92 if ((t | (int)dst) & wmask) { 93 /* 94 * Try to align operands. This cannot be done 95 * unless the low bits match. 96 */ 97 if ((t ^ (int)dst) & wmask || length < wsize) 98 t = length; 99 else 100 t = wsize - (t & wmask); 101 length -= t; 102 TLOOP1(*dst++ = *src++); 103 } 104 /* 105 * Copy whole words, then mop up any trailing bytes. 106 */ 107 t = length / wsize; 108 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize); 109 t = length & wmask; 110 TLOOP(*dst++ = *src++); 111 } else { 112 /* 113 * Copy backwards. Otherwise essentially the same. 114 * Alignment works as before, except that it takes 115 * (t&wmask) bytes to align, not wsize-(t&wmask). 116 */ 117 src += length; 118 dst += length; 119 t = (int)src; 120 if ((t | (int)dst) & wmask) { 121 if ((t ^ (int)dst) & wmask || length <= wsize) 122 t = length; 123 else 124 t &= wmask; 125 length -= t; 126 TLOOP1(*--dst = *--src); 127 } 128 t = length / wsize; 129 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src); 130 t = length & wmask; 131 TLOOP(*--dst = *--src); 132 } 133 done: 134 #if defined(MEMCOPY) || defined(MEMMOVE) 135 return (dst0); 136 #else 137 return; 138 #endif 139 } 140