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 #endif /* LIBC_SCCS and not lint */ 37 #include <sys/cdefs.h> 38 #include <sys/param.h> 39 #ifdef _KERNEL 40 #include <sys/systm.h> 41 #else 42 #include <string.h> 43 #endif 44 45 #undef memcpy 46 #undef memmove 47 48 /* 49 * sizeof(word) MUST BE A POWER OF TWO 50 * SO THAT wmask BELOW IS ALL ONES 51 */ 52 typedef long word; /* "word" used for optimal copy speed */ 53 54 #define wsize sizeof(word) 55 #define wmask (wsize - 1) 56 57 /* 58 * Copy a block of memory, handling overlap. 59 * This is the routine that actually implements 60 * (the portable versions of) bcopy, memcpy, and memmove. 61 */ 62 void * 63 memcpy(void *dst0, const void *src0, size_t length) 64 { 65 char *dst; 66 const char *src; 67 size_t t; 68 69 dst = dst0; 70 src = src0; 71 72 if (length == 0 || dst == src) { /* nothing to do */ 73 goto done; 74 } 75 76 /* 77 * Macros: loop-t-times; and loop-t-times, t>0 78 */ 79 #define TLOOP(s) if (t) TLOOP1(s) 80 #define TLOOP1(s) do { s; } while (--t) 81 82 if ((unsigned long)dst < (unsigned long)src) { 83 /* 84 * Copy forward. 85 */ 86 t = (size_t)src; /* only need low bits */ 87 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 } 98 99 length -= t; 100 TLOOP1(*dst++ = *src++); 101 } 102 /* 103 * Copy whole words, then mop up any trailing bytes. 104 */ 105 t = length / wsize; 106 TLOOP(*(word *)dst = *(const word *)src; src += wsize; 107 dst += wsize); 108 t = length & wmask; 109 TLOOP(*dst++ = *src++); 110 } else { 111 /* 112 * Copy backwards. Otherwise essentially the same. 113 * Alignment works as before, except that it takes 114 * (t&wmask) bytes to align, not wsize-(t&wmask). 115 */ 116 src += length; 117 dst += length; 118 t = (uintptr_t)src; 119 120 if ((t | (uintptr_t)dst) & wmask) { 121 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) { 122 t = length; 123 } else { 124 t &= wmask; 125 } 126 127 length -= t; 128 TLOOP1(*--dst = *--src); 129 } 130 t = length / wsize; 131 TLOOP(src -= wsize; dst -= wsize; 132 *(word *)dst = *(const word *)src); 133 t = length & wmask; 134 TLOOP(*--dst = *--src); 135 } 136 done: 137 return (dst0); 138 } 139 140 __strong_reference(memcpy, memmove); 141