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 * 3. 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 * @(#)bcopy.c 8.1 (Berkeley) 6/4/93 33 * $FreeBSD: head/lib/libc/string/bcopy.c 251069 2013-05-28 20:57:40Z emaste $ 34 */ 35 36 #include <sys/types.h> 37 38 /* 39 * sizeof(word) MUST BE A POWER OF TWO 40 * SO THAT wmask BELOW IS ALL ONES 41 */ 42 typedef int word; /* "word" used for optimal copy speed */ 43 44 #define wsize sizeof(word) 45 #define wmask (wsize - 1) 46 47 /* 48 * Copy a block of memory, handling overlap. 49 * This is the routine that actually implements 50 * (the portable versions of) bcopy, memcpy, and memmove. 51 */ 52 #if defined(MEMCOPY) || defined(MEMMOVE) 53 #include <string.h> 54 55 void * 56 #ifdef MEMCOPY 57 memcpy 58 #else 59 memmove 60 #endif 61 (void *dst0, const void *src0, size_t length) 62 #else 63 #include <strings.h> 64 65 void 66 bcopy(const void *src0, void *dst0, size_t length) 67 #endif 68 { 69 char *dst = dst0; 70 const char *src = src0; 71 size_t t; 72 73 if (length == 0 || dst == src) /* nothing to do */ 74 goto done; 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 = (uintptr_t)src; /* only need low bits */ 87 if ((t | (uintptr_t)dst) & wmask) { 88 /* 89 * Try to align operands. This cannot be done 90 * unless the low bits match. 91 */ 92 if ((t ^ (uintptr_t)dst) & wmask || length < wsize) 93 t = length; 94 else 95 t = wsize - (t & wmask); 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 = *(word *)src; src += wsize; dst += wsize); 104 t = length & wmask; 105 TLOOP(*dst++ = *src++); 106 } else { 107 /* 108 * Copy backwards. Otherwise essentially the same. 109 * Alignment works as before, except that it takes 110 * (t&wmask) bytes to align, not wsize-(t&wmask). 111 */ 112 src += length; 113 dst += length; 114 t = (uintptr_t)src; 115 if ((t | (uintptr_t)dst) & wmask) { 116 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) 117 t = length; 118 else 119 t &= wmask; 120 length -= t; 121 TLOOP1(*--dst = *--src); 122 } 123 t = length / wsize; 124 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src); 125 t = length & wmask; 126 TLOOP(*--dst = *--src); 127 } 128 done: 129 #if defined(MEMCOPY) || defined(MEMMOVE) 130 return (dst0); 131 #else 132 return; 133 #endif 134 } 135