1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * Copyright (c) 1990 The Regents of the University of California. 4 * 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Chris Torek. 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 35 #if defined(LIBC_SCCS) && !defined(lint) 36 #if 0 37 static char *sccsid = "from: @(#)bcopy.c 5.11 (Berkeley) 6/21/91"; 38 #endif 39 #if 0 40 static char *rcsid = "$NetBSD: bcopy.c,v 1.2 1997/04/16 22:09:41 thorpej Exp $"; 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 #include <sys/cdefs.h> 44 #include <sys/param.h> 45 #ifdef _KERNEL 46 #include <sys/systm.h> 47 #else 48 #include <string.h> 49 #endif 50 51 #undef memcpy 52 #undef memmove 53 54 /* 55 * sizeof(word) MUST BE A POWER OF TWO 56 * SO THAT wmask BELOW IS ALL ONES 57 */ 58 typedef long word; /* "word" used for optimal copy speed */ 59 60 #define wsize sizeof(word) 61 #define wmask (wsize - 1) 62 63 /* 64 * Copy a block of memory, handling overlap. 65 * This is the routine that actually implements 66 * (the portable versions of) bcopy, memcpy, and memmove. 67 */ 68 void * 69 memcpy(void *dst0, const void *src0, size_t length) 70 { 71 char *dst; 72 const char *src; 73 size_t t; 74 75 dst = dst0; 76 src = src0; 77 78 if (length == 0 || dst == src) { /* nothing to do */ 79 goto done; 80 } 81 82 /* 83 * Macros: loop-t-times; and loop-t-times, t>0 84 */ 85 #define TLOOP(s) if (t) TLOOP1(s) 86 #define TLOOP1(s) do { s; } while (--t) 87 88 if ((unsigned long)dst < (unsigned long)src) { 89 /* 90 * Copy forward. 91 */ 92 t = (size_t)src; /* only need low bits */ 93 94 if ((t | (uintptr_t)dst) & wmask) { 95 /* 96 * Try to align operands. This cannot be done 97 * unless the low bits match. 98 */ 99 if ((t ^ (uintptr_t)dst) & wmask || length < wsize) { 100 t = length; 101 } else { 102 t = wsize - (t & wmask); 103 } 104 105 length -= t; 106 TLOOP1(*dst++ = *src++); 107 } 108 /* 109 * Copy whole words, then mop up any trailing bytes. 110 */ 111 t = length / wsize; 112 TLOOP(*(word *)dst = *(const word *)src; src += wsize; 113 dst += wsize); 114 t = length & wmask; 115 TLOOP(*dst++ = *src++); 116 } else { 117 /* 118 * Copy backwards. Otherwise essentially the same. 119 * Alignment works as before, except that it takes 120 * (t&wmask) bytes to align, not wsize-(t&wmask). 121 */ 122 src += length; 123 dst += length; 124 t = (uintptr_t)src; 125 126 if ((t | (uintptr_t)dst) & wmask) { 127 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) { 128 t = length; 129 } else { 130 t &= wmask; 131 } 132 133 length -= t; 134 TLOOP1(*--dst = *--src); 135 } 136 t = length / wsize; 137 TLOOP(src -= wsize; dst -= wsize; 138 *(word *)dst = *(const word *)src); 139 t = length & wmask; 140 TLOOP(*--dst = *--src); 141 } 142 done: 143 return (dst0); 144 } 145 146 __strong_reference(memcpy, memmove); 147