1 files changed, 33 insertions, 44 deletions

diff --git a/src/lib/libc/string/ffs.c b/src/lib/libc/string/ffs.c
index 42bc87ddea..7dec1613a8 100644
--- a/src/lib/libc/string/ffs.c
+++ b/src/lib/libc/string/ffs.c
@@ -1,55 +1,44 @@
-/*-
- * Copyright (c) 1990 The Regents of the University of California.
- * 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. All advertising materials mentioning features or use of this software
- *    must display the following acknowledgement:
- *      This product includes software developed by the University of
- *      California, Berkeley and its contributors.
- * 4. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
- */
+/*      $OpenBSD: ffs.c,v 1.7 2005/08/08 08:05:37 espie Exp $   */
 
-#if defined(LIBC_SCCS) && !defined(lint)
-/*static char *sccsid = "from: @(#)ffs.c        5.4 (Berkeley) 5/17/90";*/
-static char *rcsid = "$Id: ffs.c,v 1.1.1.1 1995/10/18 08:42:21 deraadt Exp $";
-#endif /* LIBC_SCCS and not lint */
+/*
+ * Public domain.
+ * Written by Dale Rahn.
+ */
 
+#if !defined(_KERNEL) && !defined(_STANDALONE)
 #include <string.h>
+#else
+#include <lib/libkern/libkern.h>
+#endif
 
 /*
  * ffs -- vax ffs instruction
  */
 int
-ffs(mask)
-        register int mask;
+ffs(int mask)
 {
-        register int bit;
+        int bit;
+        unsigned int r = mask;
+        static const signed char t[16] = {
+                -28, 1, 2, 1,
+                  3, 1, 2, 1,
+                  4, 1, 2, 1,
+                  3, 1, 2, 1
+        };
+
+        bit = 0;
+        if (!(r & 0xffff)) {
+                bit += 16;
+                r >>= 16;
+        }
+        if (!(r & 0xff)) {
+                bit += 8;
+                r >>= 8;
+        }
+        if (!(r & 0xf)) {
+                bit += 4;
+                r >>= 4;
+        }
 
-        if (mask == 0)
-                return(0);
-        for (bit = 1; !(mask & 1); bit++)
-                mask >>= 1;
-        return(bit);
+        return (bit + t[ r & 0xf ]);
 }