1 /*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * 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 *rcsid = "$OpenBSD: bcopy.c,v 1.2 1996/08/19 08:33:58 tholo Exp $"; 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <string.h> 42 43 /* 44 * sizeof(word) MUST BE A POWER OF TWO 45 * SO THAT wmask BELOW IS ALL ONES 46 */ 47 typedef long word; /* "word" used for optimal copy speed */ 48 49 #define wsize sizeof(word) 50 #define wmask (wsize - 1) 51 52 /* 53 * Copy a block of memory, handling overlap. 54 * This is the routine that actually implements 55 * (the portable versions of) bcopy, memcpy, and memmove. 56 */ 57 #ifdef MEMCOPY 58 void * 59 memcpy(dst0, src0, length) 60 #else 61 #ifdef MEMMOVE 62 void * 63 memmove(dst0, src0, length) 64 #else 65 void 66 bcopy(src0, dst0, length) 67 #endif 68 #endif 69 void *dst0; 70 const void *src0; 71 register size_t length; 72 { 73 register char *dst = dst0; 74 register const char *src = src0; 75 register size_t t; 76 77 if (length == 0 || dst == src) /* nothing to do */ 78 goto done; 79 80 /* 81 * Macros: loop-t-times; and loop-t-times, t>0 82 */ 83 #define TLOOP(s) if (t) TLOOP1(s) 84 #define TLOOP1(s) do { s; } while (--t) 85 86 if ((unsigned long)dst < (unsigned long)src) { 87 /* 88 * Copy forward. 89 */ 90 t = (long)src; /* only need low bits */ 91 if ((t | (long)dst) & wmask) { 92 /* 93 * Try to align operands. This cannot be done 94 * unless the low bits match. 95 */ 96 if ((t ^ (long)dst) & wmask || length < wsize) 97 t = length; 98 else 99 t = wsize - (t & wmask); 100 length -= t; 101 TLOOP1(*dst++ = *src++); 102 } 103 /* 104 * Copy whole words, then mop up any trailing bytes. 105 */ 106 t = length / wsize; 107 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize); 108 t = length & wmask; 109 TLOOP(*dst++ = *src++); 110 } else { 111 /* 112 * Copy backwards. Otherwise essentially the same. 113 * Alignment works as before, except that it takes 114 * (t&wmask) bytes to align, not wsize-(t&wmask). 115 */ 116 src += length; 117 dst += length; 118 t = (long)src; 119 if ((t | (long)dst) & wmask) { 120 if ((t ^ (long)dst) & wmask || length <= wsize) 121 t = length; 122 else 123 t &= wmask; 124 length -= t; 125 TLOOP1(*--dst = *--src); 126 } 127 t = length / wsize; 128 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src); 129 t = length & wmask; 130 TLOOP(*--dst = *--src); 131 } 132 done: 133 #if defined(MEMCOPY) || defined(MEMMOVE) 134 return (dst0); 135 #else 136 return; 137 #endif 138 } 139