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 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char sccsid[] = "@(#)bcopy.c 8.1 (Berkeley) 6/4/93"; 39 #endif /* LIBC_SCCS and not lint */ 40 #ifndef lint 41 static const char rcsid[] = 42 "$FreeBSD: src/lib/libc/string/bcopy.c,v 1.1.1.1.14.1 2001/07/09 23:30:03 obrien Exp $"; 43 #endif 44 45 #include <sys/cdefs.h> 46 #include <string.h> 47 48 /* 49 * sizeof(word) MUST BE A POWER OF TWO 50 * SO THAT wmask BELOW IS ALL ONES 51 */ 52 typedef int word; /* "word" used for optimal copy speed */ 53 54 #define wsize sizeof(word) 55 #define wmask (wsize - 1) 56 57 /* 58 * Copy a block of memory, handling overlap. 59 * This is the routine that actually implements 60 * (the portable versions of) bcopy, memcpy, and memmove. 61 */ 62 #ifdef MEMCOPY 63 void * 64 memcpy(dst0, src0, length) 65 #else 66 #ifdef MEMMOVE 67 void * 68 memmove(dst0, src0, length) 69 #else 70 void 71 bcopy(src0, dst0, length) 72 #endif 73 #endif 74 void *dst0; 75 const void *src0; 76 register size_t length; 77 { 78 register char *dst = dst0; 79 register const char *src = src0; 80 register size_t t; 81 82 if (length == 0 || dst == src) /* nothing to do */ 83 goto done; 84 85 /* 86 * Macros: loop-t-times; and loop-t-times, t>0 87 */ 88 #define TLOOP(s) if (t) TLOOP1(s) 89 #define TLOOP1(s) do { s; } while (--t) 90 91 if ((unsigned long)dst < (unsigned long)src) { 92 /* 93 * Copy forward. 94 */ 95 t = (int)src; /* only need low bits */ 96 if ((t | (int)dst) & wmask) { 97 /* 98 * Try to align operands. This cannot be done 99 * unless the low bits match. 100 */ 101 if ((t ^ (int)dst) & wmask || length < wsize) 102 t = length; 103 else 104 t = wsize - (t & wmask); 105 length -= t; 106 TLOOP1(*dst++ = *src++); 107 } 108 /* 109 * Copy whole words, then mop up any trailing bytes. 110 */ 111 t = length / wsize; 112 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize); 113 t = length & wmask; 114 TLOOP(*dst++ = *src++); 115 } else { 116 /* 117 * Copy backwards. Otherwise essentially the same. 118 * Alignment works as before, except that it takes 119 * (t&wmask) bytes to align, not wsize-(t&wmask). 120 */ 121 src += length; 122 dst += length; 123 t = (int)src; 124 if ((t | (int)dst) & wmask) { 125 if ((t ^ (int)dst) & wmask || length <= wsize) 126 t = length; 127 else 128 t &= wmask; 129 length -= t; 130 TLOOP1(*--dst = *--src); 131 } 132 t = length / wsize; 133 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src); 134 t = length & wmask; 135 TLOOP(*--dst = *--src); 136 } 137 done: 138 #if defined(MEMCOPY) || defined(MEMMOVE) 139 return (dst0); 140 #else 141 return; 142 #endif 143 } 144