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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/generic/memmove.c
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+/* memmove -- copy memory to memory until the specified number of bytes
+ has been copied. Overlap is handled correctly.
+ Copyright (C) 1991 Free Software Foundation, Inc.
+ Contributed by Torbjorn Granlund (tege@sics.se).
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+#include <ansidecl.h>
+#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
+#endif
+#if !defined(RETURN) || !defined(rettype)
+#define RETURN(s) return (s) /* Return DEST. */
+#define rettype PTR
+#endif
+
+rettype
+DEFUN(memmove, (a1, a2, len),
+ a1const PTR a1 AND a2const PTR a2 AND 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 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 from SRCP to DSTP taking advantage of the known
+ alignment of DSTP. Number of bytes remaining is put
+ in the third argumnet, 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);
+ }
+ 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 argumnet, 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);
+}