1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #include "string.h" 34 35 /* 36 * sizeof(word) MUST BE A POWER OF TWO 37 * SO THAT wmask BELOW IS ALL ONES 38 */ 39 typedef int word; /* "word" used for optimal copy speed */ 40 41 #define wsize sizeof(word) 42 #define wmask (wsize - 1) 43 44 /* 45 * Copy a block of memory, handling overlap. 46 * This is the routine that actually implements 47 * (the portable versions of) bcopy, memcpy, and memmove. 48 */ 49 50 __attribute__((visibility("hidden"))) 51 void * 52 _libkernel_memmove(void *dst0, const void *src0, size_t length) 53 { 54 char *dst = dst0; 55 const char *src = src0; 56 size_t t; 57 58 if (length == 0 || dst == src) { /* nothing to do */ 59 goto done; 60 } 61 62 /* 63 * Macros: loop-t-times; and loop-t-times, t>0 64 */ 65 #define TLOOP(s) if (t) TLOOP1(s) 66 #define TLOOP1(s) do { s; } while (--t) 67 68 if ((unsigned long)dst < (unsigned long)src) { 69 /* 70 * Copy forward. 71 */ 72 t = (uintptr_t)src; /* only need low bits */ 73 if ((t | (uintptr_t)dst) & wmask) { 74 /* 75 * Try to align operands. This cannot be done 76 * unless the low bits match. 77 */ 78 if ((t ^ (uintptr_t)dst) & wmask || length < wsize) { 79 t = length; 80 } else { 81 t = wsize - (t & wmask); 82 } 83 length -= t; 84 TLOOP1(*dst++ = *src++); 85 } 86 /* 87 * Copy whole words, then mop up any trailing bytes. 88 */ 89 t = length / wsize; 90 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize); 91 t = length & wmask; 92 TLOOP(*dst++ = *src++); 93 } else { 94 /* 95 * Copy backwards. Otherwise essentially the same. 96 * Alignment works as before, except that it takes 97 * (t&wmask) bytes to align, not wsize-(t&wmask). 98 */ 99 src += length; 100 dst += length; 101 t = (uintptr_t)src; 102 if ((t | (uintptr_t)dst) & wmask) { 103 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) { 104 t = length; 105 } else { 106 t &= wmask; 107 } 108 length -= t; 109 TLOOP1(*--dst = *--src); 110 } 111 t = length / wsize; 112 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src); 113 t = length & wmask; 114 TLOOP(*--dst = *--src); 115 } 116 done: 117 return dst0; 118 } 119 120 __attribute__((visibility("hidden"))) 121 void 122 bcopy(const void *s1, void *s2, size_t n) 123 { 124 memcpy(s2, s1, n); 125 } 126