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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char *rcsid = "$OpenBSD: bcopy.c,v 1.3 2003/06/02 20:18:38 millert Exp $"; 35 #endif /* LIBC_SCCS and not lint */ 36 37 #include <string.h> 38 39 /* 40 * sizeof(word) MUST BE A POWER OF TWO 41 * SO THAT wmask BELOW IS ALL ONES 42 */ 43 typedef long word; /* "word" used for optimal copy speed */ 44 45 #define wsize sizeof(word) 46 #define wmask (wsize - 1) 47 48 /* 49 * Copy a block of memory, handling overlap. 50 * This is the routine that actually implements 51 * (the portable versions of) bcopy, memcpy, and memmove. 52 */ 53 #ifdef MEMCOPY 54 void * 55 memcpy(dst0, src0, length) 56 #else 57 #ifdef MEMMOVE 58 void * 59 memmove(dst0, src0, length) 60 #else 61 void 62 bcopy(src0, dst0, length) 63 #endif 64 #endif 65 void *dst0; 66 const void *src0; 67 register size_t length; 68 { 69 register char *dst = dst0; 70 register const char *src = src0; 71 register size_t t; 72 73 if (length == 0 || dst == src) /* nothing to do */ 74 goto done; 75 76 /* 77 * Macros: loop-t-times; and loop-t-times, t>0 78 */ 79 #define TLOOP(s) if (t) TLOOP1(s) 80 #define TLOOP1(s) do { s; } while (--t) 81 82 if ((unsigned long)dst < (unsigned long)src) { 83 /* 84 * Copy forward. 85 */ 86 t = (long)src; /* only need low bits */ 87 if ((t | (long)dst) & wmask) { 88 /* 89 * Try to align operands. This cannot be done 90 * unless the low bits match. 91 */ 92 if ((t ^ (long)dst) & wmask || length < wsize) 93 t = length; 94 else 95 t = wsize - (t & wmask); 96 length -= t; 97 TLOOP1(*dst++ = *src++); 98 } 99 /* 100 * Copy whole words, then mop up any trailing bytes. 101 */ 102 t = length / wsize; 103 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize); 104 t = length & wmask; 105 TLOOP(*dst++ = *src++); 106 } else { 107 /* 108 * Copy backwards. Otherwise essentially the same. 109 * Alignment works as before, except that it takes 110 * (t&wmask) bytes to align, not wsize-(t&wmask). 111 */ 112 src += length; 113 dst += length; 114 t = (long)src; 115 if ((t | (long)dst) & wmask) { 116 if ((t ^ (long)dst) & wmask || length <= wsize) 117 t = length; 118 else 119 t &= wmask; 120 length -= t; 121 TLOOP1(*--dst = *--src); 122 } 123 t = length / wsize; 124 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src); 125 t = length & wmask; 126 TLOOP(*--dst = *--src); 127 } 128 done: 129 #if defined(MEMCOPY) || defined(MEMMOVE) 130 return (dst0); 131 #else 132 return; 133 #endif 134 } 135