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ffs.S revision 1.1 
      1 /*	$NetBSD: ffs.S,v 1.1 2005/12/20 19:28:49 christos Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1991, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Ralph Campbell.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. Neither the name of the University nor the names of its contributors
     19  *    may be used to endorse or promote products derived from this software
     20  *    without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  */
     34 
     35 #include <mips/asm.h>
     36 
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 	ASMSTR("from: @(#)ffs.s	8.1 (Berkeley) 6/4/93")
     39 	ASMSTR("$NetBSD: ffs.S,v 1.1 2005/12/20 19:28:49 christos Exp $")
     40 #endif /* LIBC_SCCS and not lint */
     41 
     42 #ifdef __ABICALLS__
     43 	.abicalls
     44 #endif
     45 
     46 /* bit = ffs(value) */
     47 
     48 LEAF(ffs)
     49 	move	v0, zero
     50 	beq	a0, zero, done
     51 1:
     52 	and	v1, a0, 1		# bit set?
     53 	addu	v0, v0, 1
     54 	srl	a0, a0, 1
     55 	beq	v1, zero, 1b		# no, continue
     56 done:
     57 	j	ra
     58 END(ffs)
     59