Patch for i386 to use bsrl for libc fls().

[Venkatesh Srinivas]

Hi,

A patch to libc to use bsr for ffs.

Thanks,
-- vsFrom 8465ea0e2540def2ecd773ecde140f2e63f0d8d3 Mon Sep 17 00:00:00 2001
From: Venkatesh Srinivas <me at endeavour.zapto.org>
Date: Sun, 23 May 2010 20:32:05 -0700
Subject: [PATCH] libc: Add i386 version of fls() using bsr.

---
 lib/libc/i386/string/Makefile.inc |    2 +-
 lib/libc/i386/string/fls.S        |   44 +++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletions(-)
 create mode 100644 lib/libc/i386/string/fls.S

diff --git a/lib/libc/i386/string/Makefile.inc b/lib/libc/i386/string/Makefile.inc
index 7a1498a..c7004d4 100644
--- a/lib/libc/i386/string/Makefile.inc
+++ b/lib/libc/i386/string/Makefile.inc
@@ -2,6 +2,6 @@
 # $FreeBSD: src/lib/libc/i386/string/Makefile.inc,v 1.9 1999/08/27 23:59:29 peter Exp $
 # $DragonFly: src/lib/libc/i386/string/Makefile.inc,v 1.2 2003/06/17 04:26:43 dillon Exp $
 
-MDSRCS+=bcmp.S bcopy.S bzero.S ffs.S index.S memchr.S memcmp.S memcpy.S \
+MDSRCS+=bcmp.S bcopy.S bzero.S ffs.S fls.S index.S memchr.S memcmp.S memcpy.S \
 	memmove.S memset.S rindex.S strcat.S strchr.S strcmp.S strcpy.S \
 	strlen.S strncmp.S strrchr.S swab.S
diff --git a/lib/libc/i386/string/fls.S b/lib/libc/i386/string/fls.S
new file mode 100644
index 0000000..258092e
--- /dev/null
+++ b/lib/libc/i386/string/fls.S
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2010 The DragonFly Project
+ * 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 withough 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 "DEFS.h"
+
+/*
+ * int fls(int value)
+ * 	Finds the highest set bit in a word. Bits are numbered from 1;
+ *	a return of 0 indicates that the word was 0.
+ */
+
+ENTRY(fls)
+	bsrl	4(%esp),%eax
+	jz	1
+	addl	$1, %eax
+	ret
+
+1:	xorl	%eax,%eax
+	ret
+
-- 
1.6.4