1 /* $OpenBSD: bcopy.c,v 1.5 2005/08/08 08:05:37 espie Exp $ */ 2 /*- 3 * Copyright (c) 1990 The Regents of the University of California. 4 * All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * Chris Torek. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <string.h> 35 36 /* 37 * sizeof(word) MUST BE A POWER OF TWO 38 * SO THAT wmask BELOW IS ALL ONES 39 */ 40 typedef long word; /* "word" used for optimal copy speed */ 41 42 #define wsize sizeof(word) 43 #define wmask (wsize - 1) 44 45 /* 46 * Copy a block of memory, handling overlap. 47 * This is the routine that actually implements 48 * (the portable versions of) bcopy, memcpy, and memmove. 49 */ 50 #ifdef MEMCOPY 51 void * 52 memcpy(void *dst0, const void *src0, size_t length) 53 #else 54 #ifdef MEMMOVE 55 void * 56 memmove(void *dst0, const void *src0, size_t length) 57 #else 58 void 59 bcopy(const void *src0, void *dst0, size_t length) 60 #endif 61 #endif 62 { 63 char *dst = dst0; 64 const char *src = src0; 65 size_t t; 66 67 if (length == 0 || dst == src) /* nothing to do */ 68 goto done; 69 70 /* 71 * Macros: loop-t-times; and loop-t-times, t>0 72 */ 73 #define TLOOP(s) if (t) TLOOP1(s) 74 #define TLOOP1(s) do { s; } while (--t) 75 76 if ((unsigned long)dst < (unsigned long)src) { 77 /* 78 * Copy forward. 79 */ 80 t = (long)src; /* only need low bits */ 81 if ((t | (long)dst) & wmask) { 82 /* 83 * Try to align operands. This cannot be done 84 * unless the low bits match. 85 */ 86 if ((t ^ (long)dst) & wmask || length < wsize) 87 t = length; 88 else 89 t = wsize - (t & wmask); 90 length -= t; 91 TLOOP1(*dst++ = *src++); 92 } 93 /* 94 * Copy whole words, then mop up any trailing bytes. 95 */ 96 t = length / wsize; 97 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize); 98 t = length & wmask; 99 TLOOP(*dst++ = *src++); 100 } else { 101 /* 102 * Copy backwards. Otherwise essentially the same. 103 * Alignment works as before, except that it takes 104 * (t&wmask) bytes to align, not wsize-(t&wmask). 105 */ 106 src += length; 107 dst += length; 108 t = (long)src; 109 if ((t | (long)dst) & wmask) { 110 if ((t ^ (long)dst) & wmask || length <= wsize) 111 t = length; 112 else 113 t &= wmask; 114 length -= t; 115 TLOOP1(*--dst = *--src); 116 } 117 t = length / wsize; 118 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src); 119 t = length & wmask; 120 TLOOP(*--dst = *--src); 121 } 122 done: 123 #if defined(MEMCOPY) || defined(MEMMOVE) 124 return (dst0); 125 #else 126 return; 127 #endif 128 } 129
