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119 lines
3.8 KiB
C
119 lines
3.8 KiB
C
/* Copy memory to memory until the specified number of bytes
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has been copied. Overlap is handled correctly.
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Copyright (C) 1991-2014 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Torbjorn Granlund (tege@sics.se).
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, see <http://www.gnu.org/licenses/>. */
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#include <string.h>
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#include <memcopy.h>
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#include <pagecopy.h>
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/* All this is so that bcopy.c can #include
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this file after defining some things. */
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#ifndef a1
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#define a1 dest /* First arg is DEST. */
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#define a1const
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#define a2 src /* Second arg is SRC. */
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#define a2const const
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#undef memmove
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#endif
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#if !defined(RETURN) || !defined(rettype)
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#define RETURN(s) return (s) /* Return DEST. */
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#define rettype void *
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#endif
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#ifndef MEMMOVE
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#define MEMMOVE memmove
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#endif
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rettype
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MEMMOVE (a1, a2, len)
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a1const void *a1;
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a2const void *a2;
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size_t len;
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{
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unsigned long int dstp = (long int) dest;
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unsigned long int srcp = (long int) src;
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/* If there is no overlap between ranges, call the builtin memcpy. */
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if (dstp >= srcp + len || srcp > dstp + len)
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__builtin_memcpy (dest, src, len);
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/* This test makes the forward copying code be used whenever possible.
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Reduces the working set. */
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else if (dstp - srcp >= len) /* *Unsigned* compare! */
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{
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/* Copy from the beginning to the end. */
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/* If there not too few bytes to copy, use word copy. */
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if (len >= OP_T_THRES)
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{
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/* Copy just a few bytes to make DSTP aligned. */
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len -= (-dstp) % OPSIZ;
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BYTE_COPY_FWD (dstp, srcp, (-dstp) % OPSIZ);
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/* Copy whole pages from SRCP to DSTP by virtual address
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manipulation, as much as possible. */
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PAGE_COPY_FWD_MAYBE (dstp, srcp, len, len);
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/* Copy from SRCP to DSTP taking advantage of the known
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alignment of DSTP. Number of bytes remaining is put
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in the third argument, i.e. in LEN. This number may
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vary from machine to machine. */
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WORD_COPY_FWD (dstp, srcp, len, len);
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/* Fall out and copy the tail. */
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}
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/* There are just a few bytes to copy. Use byte memory operations. */
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BYTE_COPY_FWD (dstp, srcp, len);
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}
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else
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{
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/* Copy from the end to the beginning. */
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srcp += len;
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dstp += len;
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/* If there not too few bytes to copy, use word copy. */
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if (len >= OP_T_THRES)
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{
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/* Copy just a few bytes to make DSTP aligned. */
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len -= dstp % OPSIZ;
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BYTE_COPY_BWD (dstp, srcp, dstp % OPSIZ);
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/* Copy from SRCP to DSTP taking advantage of the known
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alignment of DSTP. Number of bytes remaining is put
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in the third argument, i.e. in LEN. This number may
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vary from machine to machine. */
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WORD_COPY_BWD (dstp, srcp, len, len);
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/* Fall out and copy the tail. */
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}
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/* There are just a few bytes to copy. Use byte memory operations. */
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BYTE_COPY_BWD (dstp, srcp, len);
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}
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RETURN (dest);
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}
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#ifndef memmove
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libc_hidden_builtin_def (memmove)
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#endif
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