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 #include <sys/stddef.h> 39 #else 40 #include <stddef.h> 41 #include <string.h> 42 #endif 43 44 #undef memcpy 45 #undef memmove 46 47 /* 48 * sizeof(word) MUST BE A POWER OF TWO 49 * SO THAT wmask BELOW IS ALL ONES 50 */ 51 typedef intptr_t word; /* "word" used for optimal copy speed */ 52 53 #define wsize sizeof(word) 54 #define wmask (wsize - 1) 55 56 /* 57 * Copy a block of memory, handling overlap. 58 * This is the routine that actually implements 59 * (the portable versions of) bcopy, memcpy, and memmove. 60 */ 61 void * 62 memmove(void *dst0, const void *src0, size_t length) 63 { 64 char *dst; 65 const char *src; 66 size_t t; 67 68 dst = dst0; 69 src = src0; 70 71 if (length == 0 || dst == src) { /* nothing to do */ 72 goto done; 73 } 74 75 /* 76 * Macros: loop-t-times; and loop-t-times, t>0 77 */ 78 #define TLOOP(s) if (t) TLOOP1(s) 79 #define TLOOP1(s) do { s; } while (--t) 80 81 if ((ptraddr_t)dst < (ptraddr_t)src) { 82 /* 83 * Copy forward. 84 */ 85 t = (size_t)src; /* only need low bits */ 86 87 if ((t | (ptraddr_t)dst) & wmask) { 88 /* 89 * Try to align operands. This cannot be done 90 * unless the low bits match. 91 */ 92 if ((t ^ (ptraddr_t)dst) & wmask || length < wsize) { 93 t = length; 94 } else { 95 t = wsize - (t & wmask); 96 } 97 98 length -= t; 99 TLOOP1(*dst++ = *src++); 100 } 101 /* 102 * Copy whole words, then mop up any trailing bytes. 103 */ 104 t = length / wsize; 105 TLOOP(*(word *)dst = *(const word *)src; src += wsize; 106 dst += wsize); 107 t = length & wmask; 108 TLOOP(*dst++ = *src++); 109 } else { 110 /* 111 * Copy backwards. Otherwise essentially the same. 112 * Alignment works as before, except that it takes 113 * (t&wmask) bytes to align, not wsize-(t&wmask). 114 */ 115 src += length; 116 dst += length; 117 t = (size_t)src; 118 119 if ((t | (ptraddr_t)dst) & wmask) { 120 if ((t ^ (ptraddr_t)dst) & wmask || length <= wsize) { 121 t = length; 122 } else { 123 t &= wmask; 124 } 125 126 length -= t; 127 TLOOP1(*--dst = *--src); 128 } 129 t = length / wsize; 130 TLOOP(src -= wsize; dst -= wsize; 131 *(word *)dst = *(const word *)src); 132 t = length & wmask; 133 TLOOP(*--dst = *--src); 134 } 135 done: 136 return (dst0); 137 } 138 139 __strong_reference(memmove, memcpy); 140