vx32

Local 9vx git repository for patches.
git clone git://r-36.net/vx32
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ffs.S (2184B)


      1 /*
      2  * Copyright (c) 1993 Winning Strategies, Inc.
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *      This product includes software developed by Winning Strategies, Inc.
     16  * 4. The name of the author may not be used to endorse or promote products
     17  *    derived from this software without specific prior written permission
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #include <asm.h>
     32 
     33 /*
     34  * ffs(value)
     35  *	finds the first bit set in value and returns the index of 
     36  *	that bit.  Bits are numbered starting from 1, starting at the
     37  *	rightmost bit.  A return value of 0 means that the argument
     38  *	was zero.
     39  *
     40  * Written by:
     41  *	J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
     42  */
     43 
     44 ENTRY(ffs)
     45 	bsfl	4(%esp),%eax
     46 	jz	L1	 		/* ZF is set if all bits are 0 */
     47 	incl	%eax			/* bits numbered from 1, not 0 */
     48 	ret
     49 
     50 	.align 2
     51 L1:	xorl	%eax,%eax		/* clear result */
     52 	ret