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Diffstat (limited to 'src/clib/memmove.c')
| -rw-r--r-- | src/clib/memmove.c | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/src/clib/memmove.c b/src/clib/memmove.c new file mode 100644 index 00000000..34a181cc --- /dev/null +++ b/src/clib/memmove.c @@ -0,0 +1,150 @@ +/*- + * See the file LICENSE for redistribution information. + * + * Copyright (c) 1996, 2012 Oracle and/or its affiliates. All rights reserved. + */ +/* + * Copyright (c) 1990, 1993 + * The Regents of the University of California. All rights reserved. + * + * 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. + * + * $Id$ + */ + +#include "db_config.h" + +#include "db_int.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 */ + +#undef wsize +#define wsize sizeof(word) +#undef wmask +#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 +/* + * PUBLIC: #ifndef HAVE_MEMCPY + * PUBLIC: void *memcpy __P((void *, const void *, size_t)); + * PUBLIC: #endif + */ +void * +memcpy(dst0, src0, length) +#else +#ifdef MEMMOVE +/* + * PUBLIC: #ifndef HAVE_MEMMOVE + * PUBLIC: void *memmove __P((void *, const void *, size_t)); + * PUBLIC: #endif + */ +void * +memmove(dst0, src0, length) +#else +void +bcopy(src0, dst0, length) +#endif +#endif + void *dst0; + const void *src0; + register size_t length; +{ + register char *dst = dst0; + register const char *src = src0; + register size_t t; + + if (length == 0 || dst == src) /* nothing to do */ + goto done; + + /* + * Macros: loop-t-times; and loop-t-times, t>0 + */ +#undef TLOOP +#define TLOOP(s) if (t) TLOOP1(s) +#undef TLOOP1 +#define TLOOP1(s) do { s; } while (--t) + + if ((unsigned long)dst < (unsigned long)src) { + /* + * Copy forward. + */ + t = (size_t)src; /* only need low bits */ + if ((t | (size_t)dst) & wmask) { + /* + * Try to align operands. This cannot be done + * unless the low bits match. + */ + if ((t ^ (size_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 = (size_t)src; + if ((t | (size_t)dst) & wmask) { + if ((t ^ (size_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 +} |