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 * 4. 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 * @(#)bcopy.c 8.1 (Berkeley) 6/4/93 33 * $FreeBSD: src/lib/libc/string/bcopy.c,v 1.7 2007/01/09 00:28:11 imp Exp $ 34 * $DragonFly: src/lib/libc/string/bcopy.c,v 1.4 2005/09/18 16:32:34 asmodai Exp $ 35 */ 36 37 #include <sys/types.h> 38 39 /* 40 * sizeof(word) MUST BE A POWER OF TWO 41 * SO THAT wmask BELOW IS ALL ONES 42 */ 43 typedef int 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 #if defined(MEMCOPY) || defined(MEMMOVE) 54 #include <string.h> 55 56 void * 57 #ifdef MEMCOPY 58 memcpy 59 #else 60 memmove 61 #endif 62 (void *dst0, const void *src0, size_t length) 63 #else 64 #include <strings.h> 65 66 void 67 bcopy(const void *src0, void *dst0, size_t length) 68 #endif 69 { 70 char *dst = dst0; 71 const char *src = src0; 72 size_t t; 73 74 if (length == 0 || dst == src) /* nothing to do */ 75 goto done; 76 77 /* 78 * Macros: loop-t-times; and loop-t-times, t>0 79 */ 80 #define TLOOP(s) if (t) TLOOP1(s) 81 #define TLOOP1(s) do { s; } while (--t) 82 83 if ((unsigned long)dst < (unsigned long)src) { 84 /* 85 * Copy forward. 86 */ 87 t = (uintptr_t)src; /* only need low bits */ 88 if ((t | (uintptr_t)dst) & wmask) { 89 /* 90 * Try to align operands. This cannot be done 91 * unless the low bits match. 92 */ 93 if ((t ^ (uintptr_t)dst) & wmask || length < wsize) 94 t = length; 95 else 96 t = wsize - (t & wmask); 97 length -= t; 98 TLOOP1(*dst++ = *src++); 99 } 100 /* 101 * Copy whole words, then mop up any trailing bytes. 102 */ 103 t = length / wsize; 104 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize); 105 t = length & wmask; 106 TLOOP(*dst++ = *src++); 107 } else { 108 /* 109 * Copy backwards. Otherwise essentially the same. 110 * Alignment works as before, except that it takes 111 * (t&wmask) bytes to align, not wsize-(t&wmask). 112 */ 113 src += length; 114 dst += length; 115 t = (uintptr_t)src; 116 if ((t | (uintptr_t)dst) & wmask) { 117 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) 118 t = length; 119 else 120 t &= wmask; 121 length -= t; 122 TLOOP1(*--dst = *--src); 123 } 124 t = length / wsize; 125 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src); 126 t = length & wmask; 127 TLOOP(*--dst = *--src); 128 } 129 done: 130 #if defined(MEMCOPY) || defined(MEMMOVE) 131 return (dst0); 132 #else 133 return; 134 #endif 135 } 136