128 lines
3.7 KiB
C
128 lines
3.7 KiB
C
/* $OpenBSD: bcopy.c,v 1.5 2005/08/08 08:05:37 espie Exp $ */
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/*-
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Chris Torek.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <string.h>
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/*
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* sizeof(word) MUST BE A POWER OF TWO
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* SO THAT wmask BELOW IS ALL ONES
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*/
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typedef long word; /* "word" used for optimal copy speed */
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#define wsize sizeof(word)
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#define wmask (wsize - 1)
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/*
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* Copy a block of memory, handling overlap.
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* This is the routine that actually implements
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* (the portable versions of) bcopy, memcpy, and memmove.
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*/
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#ifdef MEMCOPY
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void *
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memcpy(void *dst0, const void *src0, size_t length)
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#else
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#ifdef MEMMOVE
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void *
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memmove(void *dst0, const void *src0, size_t length)
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#else
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void
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bcopy(const void *src0, void *dst0, size_t length)
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#endif
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#endif
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{
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char *dst = dst0;
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const char *src = src0;
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size_t t;
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if (length == 0 || dst == src) /* nothing to do */
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goto done;
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/*
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* Macros: loop-t-times; and loop-t-times, t>0
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*/
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#define TLOOP(s) if (t) TLOOP1(s)
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#define TLOOP1(s) do { s; } while (--t)
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if ((unsigned long)dst < (unsigned long)src) {
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/*
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* Copy forward.
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*/
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t = (long)src; /* only need low bits */
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if ((t | (long)dst) & wmask) {
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/*
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* Try to align operands. This cannot be done
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* unless the low bits match.
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*/
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if ((t ^ (long)dst) & wmask || length < wsize)
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t = length;
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else
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t = wsize - (t & wmask);
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length -= t;
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TLOOP1(*dst++ = *src++);
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}
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/*
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* Copy whole words, then mop up any trailing bytes.
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*/
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t = length / wsize;
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TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
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t = length & wmask;
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TLOOP(*dst++ = *src++);
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} else {
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/*
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* Copy backwards. Otherwise essentially the same.
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* Alignment works as before, except that it takes
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* (t&wmask) bytes to align, not wsize-(t&wmask).
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*/
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src += length;
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dst += length;
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t = (long)src;
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if ((t | (long)dst) & wmask) {
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if ((t ^ (long)dst) & wmask || length <= wsize)
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t = length;
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else
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t &= wmask;
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length -= t;
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TLOOP1(*--dst = *--src);
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}
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t = length / wsize;
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TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
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t = length & wmask;
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TLOOP(*--dst = *--src);
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}
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done:
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#if defined(MEMCOPY) || defined(MEMMOVE)
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return (dst0);
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#else
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return;
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#endif
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}
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