1/*- 2 * See the file LICENSE for redistribution information. 3 * 4 * Copyright (c) 1996,2008 Oracle. All rights reserved. 5 */ 6/* 7 * Copyright (c) 1990, 1993 8 * The Regents of the University of California. All rights reserved. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * $Id: memmove.c,v 12.8 2008/01/08 20:58:08 bostic Exp $ 35 */ 36 37#include "db_config.h" 38 39#include "db_int.h" 40 41/* 42 * sizeof(word) MUST BE A POWER OF TWO 43 * SO THAT wmask BELOW IS ALL ONES 44 */ 45typedef int word; /* "word" used for optimal copy speed */ 46 47#undef wsize 48#define wsize sizeof(word) 49#undef wmask 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/* 59 * PUBLIC: #ifndef HAVE_MEMCPY 60 * PUBLIC: void *memcpy __P((void *, const void *, size_t)); 61 * PUBLIC: #endif 62 */ 63void * 64memcpy(dst0, src0, length) 65#else 66#ifdef MEMMOVE 67/* 68 * PUBLIC: #ifndef HAVE_MEMMOVE 69 * PUBLIC: void *memmove __P((void *, const void *, size_t)); 70 * PUBLIC: #endif 71 */ 72void * 73memmove(dst0, src0, length) 74#else 75void 76bcopy(src0, dst0, length) 77#endif 78#endif 79 void *dst0; 80 const void *src0; 81 register size_t length; 82{ 83 register char *dst = dst0; 84 register const char *src = src0; 85 register size_t t; 86 87 if (length == 0 || dst == src) /* nothing to do */ 88 goto done; 89 90 /* 91 * Macros: loop-t-times; and loop-t-times, t>0 92 */ 93#undef TLOOP 94#define TLOOP(s) if (t) TLOOP1(s) 95#undef TLOOP1 96#define TLOOP1(s) do { s; } while (--t) 97 98 if ((unsigned long)dst < (unsigned long)src) { 99 /* 100 * Copy forward. 101 */ 102 t = (size_t)src; /* only need low bits */ 103 if ((t | (size_t)dst) & wmask) { 104 /* 105 * Try to align operands. This cannot be done 106 * unless the low bits match. 107 */ 108 if ((t ^ (size_t)dst) & wmask || length < wsize) 109 t = length; 110 else 111 t = wsize - (t & wmask); 112 length -= t; 113 TLOOP1(*dst++ = *src++); 114 } 115 /* 116 * Copy whole words, then mop up any trailing bytes. 117 */ 118 t = length / wsize; 119 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize); 120 t = length & wmask; 121 TLOOP(*dst++ = *src++); 122 } else { 123 /* 124 * Copy backwards. Otherwise essentially the same. 125 * Alignment works as before, except that it takes 126 * (t&wmask) bytes to align, not wsize-(t&wmask). 127 */ 128 src += length; 129 dst += length; 130 t = (size_t)src; 131 if ((t | (size_t)dst) & wmask) { 132 if ((t ^ (size_t)dst) & wmask || length <= wsize) 133 t = length; 134 else 135 t &= wmask; 136 length -= t; 137 TLOOP1(*--dst = *--src); 138 } 139 t = length / wsize; 140 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src); 141 t = length & wmask; 142 TLOOP(*--dst = *--src); 143 } 144done: 145#if defined(MEMCOPY) || defined(MEMMOVE) 146 return (dst0); 147#else 148 return; 149#endif 150} 151