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/* $NetBSD: bcopy.c,v 1.3 2007/06/04 18:19:27 christos Exp $ */
/*-
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Chris Torek.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h> #if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)bcopy.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: bcopy.c,v 1.3 2007/06/04 18:19:27 christos Exp ___FCKpd___1quot;); #endif #endif /* LIBC_SCCS and not lint */ #if !defined(_KERNEL) && !defined(_STANDALONE) #include <assert.h> #include <string.h>
#else
#include <lib/libkern/libkern.h> #endif #ifdef _FORTIFY_SOURCE #undef bcopy #undef memcpy #undef memmove #endif /*
* sizeof(word) MUST BE A POWER OF TWO
* SO THAT wmask BELOW IS ALL ONES
*/
typedef long word; /* "word" used for optimal copy speed */ #define wsize sizeof(word) #define wmask (wsize - 1)
/*
* Copy a block of memory, handling overlap.
* This is the routine that actually implements
* (the portable versions of) bcopy, memcpy, and memmove.
*/
#ifdef MEMCOPY void * memcpy(void *dst0, const void *src0, size_t length)
#else
#ifdef MEMMOVE void * memmove(void *dst0, const void *src0, size_t length)
#else
void bcopy(const void *src0, void *dst0, size_t length) #endif #endif { char *dst = dst0; const char *src = src0; size_t t; unsigned long u; #if !defined(_KERNEL) _DIAGASSERT(dst0 != 0); _DIAGASSERT(src0 != 0); #endif if (length == 0 || dst == src) /* nothing to do */ goto done;
/*
* Macros: loop-t-times; and loop-t-times, t>0
*/
#define TLOOP(s) if (t) TLOOP1(s) #define TLOOP1(s) do { s; } while (--t) if ((unsigned long)dst < (unsigned long)src) {
/*
* Copy forward.
*/
u = (unsigned long)src; /* only need low bits */ if ((u | (unsigned long)dst) & wmask) {
/*
* Try to align operands. This cannot be done
* unless the low bits match.
*/
if ((u ^ (unsigned long)dst) & wmask || length < wsize) t = length;
else
t = wsize - (size_t)(u & wmask); length -= t; TLOOP1(*dst++ = *src++); }
/*
* Copy whole words, then mop up any trailing bytes.
*/
t = length / wsize; TLOOP(*(word *)(void *)dst = *(const word *)(const void *)src; src += wsize; dst += wsize); t = length & wmask; TLOOP(*dst++ = *src++);
} else {
/*
* Copy backwards. Otherwise essentially the same.
* Alignment works as before, except that it takes
* (t&wmask) bytes to align, not wsize-(t&wmask).
*/
src += length; dst += length; _DIAGASSERT((unsigned long)dst >= (unsigned long)dst0); _DIAGASSERT((unsigned long)src >= (unsigned long)src0); u = (unsigned long)src; if ((u | (unsigned long)dst) & wmask) { if ((u ^ (unsigned long)dst) & wmask || length <= wsize) t = length;
else
t = (size_t)(u & wmask); length -= t; TLOOP1(*--dst = *--src); } t = length / wsize; TLOOP(src -= wsize; dst -= wsize; *(word *)(void *)dst = *(const word *)(const void *)src); t = length & wmask; TLOOP(*--dst = *--src); } done: #if defined(MEMCOPY) || defined(MEMMOVE) return (dst0);
#else
return;
#endif } |
memcpy的實現(轉載)
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