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 $"; 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 #include <sys/cdefs.h> 44 __FBSDID("$FreeBSD$"); 45 46 #include <sys/param.h> 47 #ifdef _KERNEL 48 #include <sys/systm.h> 49 #else 50 #include <string.h> 51 #endif 52 53 #undef memcpy 54 #undef memmove 55 56 /* 57 * sizeof(word) MUST BE A POWER OF TWO 58 * SO THAT wmask BELOW IS ALL ONES 59 */ 60 typedef long word; /* "word" used for optimal copy speed */ 61 62 #define wsize sizeof(word) 63 #define wmask (wsize - 1) 64 65 /* 66 * Copy a block of memory, handling overlap. 67 * This is the routine that actually implements 68 * (the portable versions of) bcopy, memcpy, and memmove. 69 */ 70 void * 71 memcpy(void *dst0, const void *src0, size_t length) 72 { 73 char *dst; 74 const char *src; 75 size_t t; 76 77 dst = dst0; 78 src = src0; 79 80 if (length == 0 || dst == src) { /* nothing to do */ 81 goto done; 82 } 83 84 /* 85 * Macros: loop-t-times; and loop-t-times, t>0 86 */ 87 #define TLOOP(s) if (t) TLOOP1(s) 88 #define TLOOP1(s) do { s; } while (--t) 89 90 if ((unsigned long)dst < (unsigned long)src) { 91 /* 92 * Copy forward. 93 */ 94 t = (size_t)src; /* only need low bits */ 95 96 if ((t | (uintptr_t)dst) & wmask) { 97 /* 98 * Try to align operands. This cannot be done 99 * unless the low bits match. 100 */ 101 if ((t ^ (uintptr_t)dst) & wmask || length < wsize) { 102 t = length; 103 } else { 104 t = wsize - (t & wmask); 105 } 106 107 length -= t; 108 TLOOP1(*dst++ = *src++); 109 } 110 /* 111 * Copy whole words, then mop up any trailing bytes. 112 */ 113 t = length / wsize; 114 TLOOP(*(word *)dst = *(const word *)src; src += wsize; 115 dst += wsize); 116 t = length & wmask; 117 TLOOP(*dst++ = *src++); 118 } else { 119 /* 120 * Copy backwards. Otherwise essentially the same. 121 * Alignment works as before, except that it takes 122 * (t&wmask) bytes to align, not wsize-(t&wmask). 123 */ 124 src += length; 125 dst += length; 126 t = (uintptr_t)src; 127 128 if ((t | (uintptr_t)dst) & wmask) { 129 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) { 130 t = length; 131 } else { 132 t &= wmask; 133 } 134 135 length -= t; 136 TLOOP1(*--dst = *--src); 137 } 138 t = length / wsize; 139 TLOOP(src -= wsize; dst -= wsize; 140 *(word *)dst = *(const word *)src); 141 t = length & wmask; 142 TLOOP(*--dst = *--src); 143 } 144 done: 145 return (dst0); 146 } 147 148 __strong_reference(memcpy, memmove); 149