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 1.4 2005/09/18 16:32:34 asmodai 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(void *dst0, const void *src0, size_t length) 61 #else 62 #ifdef MEMMOVE 63 void * 64 memmove(void *dst0, const void *src0, size_t length) 65 #else 66 void 67 bcopy(const void *src0, void *dst0, size_t length) 68 #endif 69 #endif 70 { 71 char *dst = dst0; 72 const char *src = src0; 73 size_t t; 74 75 if (length == 0 || dst == src) /* nothing to do */ 76 goto done; 77 78 /* 79 * Macros: loop-t-times; and loop-t-times, t>0 80 */ 81 #define TLOOP(s) if (t) TLOOP1(s) 82 #define TLOOP1(s) do { s; } while (--t) 83 84 if ((unsigned long)dst < (unsigned long)src) { 85 /* 86 * Copy forward. 87 */ 88 t = (int)src; /* only need low bits */ 89 if ((t | (int)dst) & wmask) { 90 /* 91 * Try to align operands. This cannot be done 92 * unless the low bits match. 93 */ 94 if ((t ^ (int)dst) & wmask || length < wsize) 95 t = length; 96 else 97 t = wsize - (t & wmask); 98 length -= t; 99 TLOOP1(*dst++ = *src++); 100 } 101 /* 102 * Copy whole words, then mop up any trailing bytes. 103 */ 104 t = length / wsize; 105 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize); 106 t = length & wmask; 107 TLOOP(*dst++ = *src++); 108 } else { 109 /* 110 * Copy backwards. Otherwise essentially the same. 111 * Alignment works as before, except that it takes 112 * (t&wmask) bytes to align, not wsize-(t&wmask). 113 */ 114 src += length; 115 dst += length; 116 t = (int)src; 117 if ((t | (int)dst) & wmask) { 118 if ((t ^ (int)dst) & wmask || length <= wsize) 119 t = length; 120 else 121 t &= wmask; 122 length -= t; 123 TLOOP1(*--dst = *--src); 124 } 125 t = length / wsize; 126 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src); 127 t = length & wmask; 128 TLOOP(*--dst = *--src); 129 } 130 done: 131 #if defined(MEMCOPY) || defined(MEMMOVE) 132 return (dst0); 133 #else 134 return; 135 #endif 136 } 137