1 files changed, 68 insertions, 0 deletions
diff --git a/sysdeps/i386/memcmp.S b/sysdeps/i386/memcmp.S
new file mode 100644
index 0000000000..f16b44a1b4
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+++ b/sysdeps/i386/memcmp.S
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+/* memcmp -- compare two memory blocks for differences in the first COUNT
+	     bytes.
+Copyright (C) 1995 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 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., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+#include <sysdep.h>
+#include "asm-syntax.h"
+
+/*
+   INPUT PARAMETERS:
+   block1	(sp + 4)
+   block2	(sp + 8)
+   len		(sp + 12)
+*/
+
+	.text
+ENTRY (memcmp)
+	pushl %esi		/* Save callee-safe registers.  */
+	movl %edi, %edx		/* Note that %edx is not used and can
+				   so be used to save %edi.  It's faster.  */
+
+	movl 12(%esp), %esi	/* Load address of block #1.  */
+	movl 16(%esp), %edi	/* Load address of block #2.  */
+	movl 20(%esp), %ecx	/* Load maximal length of compare area.  */
+
+	cld			/* Set direction of comparison.  */
+
+	xorl %eax, %eax		/* Default result.  */
+
+	repe			/* Compare at most %ecx bytes.  */
+	cmpsb
+	jz L1			/* If even last byte was equal we return 0.  */
+
+	/* The memory blocks are not equal.  So result of the last
+	   subtraction is present in the carry flag.  It is set when
+	   the byte in block #2 is bigger.  In this case we have to
+	   return -1 (=0xffffffff), else 1.  */
+	sbbl %eax, %eax		/* This is tricky.  %eax == 0 and carry is set
+				   or not depending on last subtraction.  */
+
+	/* At this point %eax == 0, if the byte of block #1 was bigger, and
+	   0xffffffff if the last byte of block #2 was bigger.  The later
+	   case is already correct but the former needs a little adjustment.
+	   Note that the following operation does not change 0xffffffff.  */
+	orb $1, %al		/* Change 0 to 1.  */
+
+L1:	popl %esi		/* Restore registers.  */
+	movl %edx, %edi
+
+	ret
+
+#undef bcmp
+weak_alias (memcmp, bcmp)