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/* Copy memory to memory until the specified number of bytes
has been copied. Overlap is handled correctly.
Copyright (C) 1991-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <string.h>
#include <memcopy.h>
/* All this is so that bcopy.c can #include
this file after defining some things. */
#ifndef a1
#define a1 dest /* First arg is DEST. */
#define a1const
#define a2 src /* Second arg is SRC. */
#define a2const const
#undef memmove
#endif
#if !defined(RETURN) || !defined(rettype)
#define RETURN(s) return (s) /* Return DEST. */
#define rettype void *
#endif
#ifndef MEMMOVE
#define MEMMOVE memmove
#endif
rettype
inhibit_loop_to_libcall
MEMMOVE (a1const void *a1, a2const void *a2, size_t len)
{
unsigned long int dstp = (long int) dest;
unsigned long int srcp = (long int) src;
/* This test makes the forward copying code be used whenever possible.
Reduces the working set. */
if (dstp - srcp >= len) /* *Unsigned* compare! */
{
/* Copy from the beginning to the end. */
#if MEMCPY_OK_FOR_FWD_MEMMOVE
dest = memcpy (dest, src, len);
#else
/* If there not too few bytes to copy, use word copy. */
if (len >= OP_T_THRES)
{
/* Copy just a few bytes to make DSTP aligned. */
len -= (-dstp) % OPSIZ;
BYTE_COPY_FWD (dstp, srcp, (-dstp) % OPSIZ);
/* Copy whole pages from SRCP to DSTP by virtual address
manipulation, as much as possible. */
PAGE_COPY_FWD_MAYBE (dstp, srcp, len, len);
/* Copy from SRCP to DSTP taking advantage of the known
alignment of DSTP. Number of bytes remaining is put
in the third argument, i.e. in LEN. This number may
vary from machine to machine. */
WORD_COPY_FWD (dstp, srcp, len, len);
/* Fall out and copy the tail. */
}
/* There are just a few bytes to copy. Use byte memory operations. */
BYTE_COPY_FWD (dstp, srcp, len);
#endif /* MEMCPY_OK_FOR_FWD_MEMMOVE */
}
else
{
/* Copy from the end to the beginning. */
srcp += len;
dstp += len;
/* If there not too few bytes to copy, use word copy. */
if (len >= OP_T_THRES)
{
/* Copy just a few bytes to make DSTP aligned. */
len -= dstp % OPSIZ;
BYTE_COPY_BWD (dstp, srcp, dstp % OPSIZ);
/* Copy from SRCP to DSTP taking advantage of the known
alignment of DSTP. Number of bytes remaining is put
in the third argument, i.e. in LEN. This number may
vary from machine to machine. */
WORD_COPY_BWD (dstp, srcp, len, len);
/* Fall out and copy the tail. */
}
/* There are just a few bytes to copy. Use byte memory operations. */
BYTE_COPY_BWD (dstp, srcp, len);
}
RETURN (dest);
}
#ifndef memmove
libc_hidden_builtin_def (memmove)
#endif
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