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 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char sccsid[] = "@(#)bcopy.c 8.1 (Berkeley) 6/4/93"; 35 #endif /* LIBC_SCCS and not lint */ 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 #include <sys/types.h> 40 41 /* 42 * sizeof(word) MUST BE A POWER OF TWO 43 * SO THAT wmask BELOW IS ALL ONES 44 */ 45 typedef int word; /* "word" used for optimal copy speed */ 46 47 #define wsize sizeof(word) 48 #define wmask (wsize - 1) 49 50 /* 51 * Copy a block of memory, handling overlap. 52 * This is the routine that actually implements 53 * (the portable versions of) bcopy, memcpy, and memmove. 54 */ 55 #if defined(MEMCOPY) || defined(MEMMOVE) 56 #include <string.h> 57 58 void * 59 #ifdef MEMCOPY 60 memcpy 61 #else 62 memmove 63 #endif 64 (void *dst0, const void *src0, size_t length) 65 #else 66 #include <strings.h> 67 68 void 69 bcopy(const void *src0, void *dst0, size_t length) 70 #endif 71 { 72 char *dst = dst0; 73 const char *src = src0; 74 size_t t; 75 76 if (length == 0 || dst == src) /* nothing to do */ 77 goto done; 78 79 /* 80 * Macros: loop-t-times; and loop-t-times, t>0 81 */ 82 #define TLOOP(s) if (t) TLOOP1(s) 83 #define TLOOP1(s) do { s; } while (--t) 84 85 if ((unsigned long)dst < (unsigned long)src) { 86 /* 87 * Copy forward. 88 */ 89 t = (uintptr_t)src; /* only need low bits */ 90 if ((t | (uintptr_t)dst) & wmask) { 91 /* 92 * Try to align operands. This cannot be done 93 * unless the low bits match. 94 */ 95 if ((t ^ (uintptr_t)dst) & wmask || length < wsize) 96 t = length; 97 else 98 t = wsize - (t & wmask); 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 = *(word *)src; src += wsize; 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 = (uintptr_t)src; 118 if ((t | (uintptr_t)dst) & wmask) { 119 if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) 120 t = length; 121 else 122 t &= wmask; 123 length -= t; 124 TLOOP1(*--dst = *--src); 125 } 126 t = length / wsize; 127 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src); 128 t = length & wmask; 129 TLOOP(*--dst = *--src); 130 } 131 done: 132 #if defined(MEMCOPY) || defined(MEMMOVE) 133 return (dst0); 134 #else 135 return; 136 #endif 137 } 138