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 #include <sys/param.h> 36 #ifdef _KERNEL 37 #include <sys/systm.h> 38 #else 39 #include <string.h> 40 #endif 41 42 #undef memcpy 43 #undef memmove 44 45 /* 46 * sizeof(word) MUST BE A POWER OF TWO 47 * SO THAT wmask BELOW IS ALL ONES 48 */ 49 typedef long word; /* "word" used for optimal copy speed */ 50 51 #define wsize sizeof(word) 52 #define wmask (wsize - 1) 53 54 /* 55 * Copy a block of memory, handling overlap. 56 * This is the routine that actually implements 57 * (the portable versions of) bcopy, memcpy, and memmove. 58 */ 59 void * 60 memcpy(void *dst0, const void *src0, size_t length) 61 { 62 char *dst; 63 const char *src; 64 size_t t; 65 66 dst = dst0; 67 src = src0; 68 69 if (length == 0 || dst == src) { /* nothing to do */ 70 goto done; 71 } 72 73 /* 74 * Macros: loop-t-times; and loop-t-times, t>0 75 */ 76 #define TLOOP(s) if (t) TLOOP1(s) 77 #define TLOOP1(s) do { s; } while (--t) 78 79 if ((unsigned long)dst < (unsigned long)src) { 80 /* 81 * Copy forward. 82 */ 83 t = (size_t)src; /* only need low bits */ 84 85 if ((t | (uintptr_t)dst) & wmask) { 86 /* 87 * Try to align operands. This cannot be done 88 * unless the low bits match. 89 */ 90 if ((t ^ (uintptr_t)dst) & wmask || length < wsize) { 91 t = length; 92 } else { 93 t = wsize - (t & wmask); 94 } 95 96 length -= t; 97 TLOOP1(*dst++ = *src++); 98 } 99 /* 100 * Copy whole words, then mop up any trailing bytes. 101 */ 102 t = length / wsize; 103 TLOOP(*(word *)dst = *(const word *)src; src += wsize; 104 dst += wsize); 105 t = length & wmask; 106 TLOOP(*dst++ = *src++); 107 } else { 108 /* 109 * Copy backwards. Otherwise essentially the same. 110 * Alignment works as before, except that it takes 111 * (t&wmask) bytes to align, not wsize-(t&wmask). 112 */ 113 src += length; 114 dst += length; 115 t = (uintptr_t)src; 116 117 if ((t | (uintptr_t)dst) & wmask) { 118 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) { 119 t = length; 120 } else { 121 t &= wmask; 122 } 123 124 length -= t; 125 TLOOP1(*--dst = *--src); 126 } 127 t = length / wsize; 128 TLOOP(src -= wsize; dst -= wsize; 129 *(word *)dst = *(const word *)src); 130 t = length & wmask; 131 TLOOP(*--dst = *--src); 132 } 133 done: 134 return (dst0); 135 } 136 137 __strong_reference(memcpy, memmove); 138