freebsd-dev/lib/libc/string/bcopy.c
Pedro F. Giffuni 8a16b7a18f General further adoption of SPDX licensing ID tags.
Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
2017-11-20 19:49:47 +00:00

140 lines
4.0 KiB
C

/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* 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.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)bcopy.c 8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
/*
* sizeof(word) MUST BE A POWER OF TWO
* SO THAT wmask BELOW IS ALL ONES
*/
typedef int 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.
*/
#if defined(MEMCOPY) || defined(MEMMOVE)
#include <string.h>
void *
#ifdef MEMCOPY
memcpy
#else
memmove
#endif
(void *dst0, const void *src0, size_t length)
#else
#include <strings.h>
void
bcopy(const void *src0, void *dst0, size_t length)
#endif
{
char *dst = dst0;
const char *src = src0;
size_t t;
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.
*/
t = (uintptr_t)src; /* only need low bits */
if ((t | (uintptr_t)dst) & wmask) {
/*
* Try to align operands. This cannot be done
* unless the low bits match.
*/
if ((t ^ (uintptr_t)dst) & wmask || length < wsize)
t = length;
else
t = wsize - (t & wmask);
length -= t;
TLOOP1(*dst++ = *src++);
}
/*
* Copy whole words, then mop up any trailing bytes.
*/
t = length / wsize;
TLOOP(*(word *)dst = *(word *)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;
t = (uintptr_t)src;
if ((t | (uintptr_t)dst) & wmask) {
if ((t ^ (uintptr_t)dst) & wmask || length <= wsize)
t = length;
else
t &= wmask;
length -= t;
TLOOP1(*--dst = *--src);
}
t = length / wsize;
TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
t = length & wmask;
TLOOP(*--dst = *--src);
}
done:
#if defined(MEMCOPY) || defined(MEMMOVE)
return (dst0);
#else
return;
#endif
}