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authorscottr <scottr@NetBSD.org>2001-02-05 00:17:22 +0000
committerscottr <scottr@NetBSD.org>2001-02-05 00:17:22 +0000
commited472989a6c27e05a5793e4f3bdf030d9cd023eb (patch)
tree62f201f5ee0b32e0ff3c2a25ed53c57fab890ff5
parent7b10d18078192f45bc5eb6f229adf22059726132 (diff)
Implement a significantly improved version of memccpy(), with thanks to
Ignatios Souvatzis for correcting the SVR4 ABI code and for a few micro-optimizations that followed from these changes. The overall improvement was measured at 3-4x for copies of at least 4 bytes on the 68030, and 8 bytes on the 68040. For smaller copies the improvement was still measurable, if not as dramatic.
-rw-r--r--lib/libc/arch/m68k/string/memccpy.S82
1 files changed, 82 insertions, 0 deletions
diff --git a/lib/libc/arch/m68k/string/memccpy.S b/lib/libc/arch/m68k/string/memccpy.S
new file mode 100644
index 00000000000..4a88a9c8e39
--- /dev/null
+++ b/lib/libc/arch/m68k/string/memccpy.S
@@ -0,0 +1,82 @@
+/* $NetBSD: memccpy.S,v 1.1 2001/02/05 00:17:22 scottr Exp $ */
+
+/*
+ * Copyright (C) 1999 Scott Reynolds. 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. The name of the author may not be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
+ */
+
+#include <machine/asm.h>
+
+#if defined(LIBC_SCCS) && !defined(lint)
+ RCSID("$NetBSD: memccpy.S,v 1.1 2001/02/05 00:17:22 scottr Exp $")
+#endif /* LIBC_SCCS and not lint */
+
+ENTRY(memccpy)
+ movl %sp@(16),%d0 | count
+ jeq Lmcbail | nothing to do
+
+ movl %sp@(4),%a0 | a0 = toaddr
+ subql #1,%d0 | prepare count for DBcc loop
+ movl %sp@(8),%a1 | a1 = fromaddr
+ movl %sp@(12),%d1 | d1 = terminator
+ jeq Lmcloop | handle ASCII NUL specially
+
+ movl %d2,%sp@- | save scratch register
+Lmcnzloop:
+ movb %a1@+,%d2 | move a byte
+ movb %d2,%a0@+
+ cmpb %d2,%d1 | found the terminator?
+ dbeq %d0,Lmcnzloop | if not, keep transferring,
+ jeq Lmcnzdone | otherwise done
+ clrw %d0 | check to see if more to do
+ subql #1,%d0
+ jcc Lmcnzloop | yes, keep going...
+
+ movl %sp@+,%d2 | restore scratch register
+ movql #0,%d0 | no terminator found, return NULL
+#ifdef __SVR4_ABI__
+ movl %d0,%a0 | XXX maybe use lea to avoid stall?
+#endif
+ rts
+
+Lmcloop:
+ movb %a1@+,%a0@+ | move a byte; was it NUL?
+ dbeq %d0,Lmcloop | if not, keep transferring,
+ jeq Lmcdone | otherwise done
+ clrw %d0 | check to see if more to do
+ subql #1,%d0
+ jcc Lmcloop | yes, keep going...
+ | Note: %d0 is now -1!
+ movql #0,%d0 | no terminator found, return NULL
+Lmcbail:
+#ifdef __SVR4_ABI__
+ movl %d0,%a0 | XXX maybe use lea to avoid stall?
+#endif
+ rts
+
+Lmcnzdone:
+ movl %sp@+,%d2 | restore scratch register
+Lmcdone:
+ movl %a0,%d0
+ rts