67dd4d6995
The former gives 0-based indexes, which is what our implementation returns, making the "- 1" unnecessary. Change-Id: I172ab5e06695be62e4a18d4fd0415b8314f5dc26
42 lines
1.4 KiB
C
42 lines
1.4 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2008 by Michael Sevakis
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include "config.h"
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#include <inttypes.h>
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/*
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* Find the index of the least significant set bit in the word.
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* return values:
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* 0 - bit 0 is set
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* 1 - bit 1 is set
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* ...
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* 31 - bit 31 is set
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* 32 - no bits set
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*/
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int find_first_set_bit(uint32_t val)
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{
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if (val == 0)
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return 32;
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/* __builtin_ctz[l[l]]: Returns the number of trailing 0-bits in x,
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* starting at the least significant bit position. If x is 0, the result
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* is undefined. */
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return __builtin_ctz(val);
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}
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