1994-08-05 01:19:12 +00:00
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/*
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* Copyright (c) 1993 Winning Strategies, Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Winning Strategies, Inc.
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* 4. The name of the author may not be used to endorse or promote products
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2002-06-02 20:05:59 +00:00
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* derived from this software without specific prior written permission
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1994-08-05 01:19:12 +00:00
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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2001-10-24 20:29:14 +00:00
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#include <machine/asm.h>
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2002-03-23 02:44:19 +00:00
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__FBSDID("$FreeBSD$");
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1994-08-05 01:19:12 +00:00
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/*
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* ffs(value)
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* finds the first bit set in value and returns the index of
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* that bit. Bits are numbered starting from 1, starting at the
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* rightmost bit. A return value of 0 means that the argument
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* was zero.
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*
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* Written by:
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* J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
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*/
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ENTRY(ffs)
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bsfl 4(%esp),%eax
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jz L1 /* ZF is set if all bits are 0 */
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incl %eax /* bits numbered from 1, not 0 */
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ret
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.align 2
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L1: xorl %eax,%eax /* clear result */
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ret
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