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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2008 by Michael Sevakis
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "config.h"
#include <inttypes.h>
/* find_first_set_bit() - this is a C version of the ffs algorithm devised
* by D.Seal and posted to comp.sys.arm on 16 Feb 1994.
*
* Find the index of the least significant set bit in the word.
* return values:
* 0 - bit 0 is set
* 1 - bit 1 is set
* ...
* 31 - bit 31 is set
* 32 - no bits set
*/
/* Table shared with assembly code */
const uint8_t L_ffs_table[64] ICONST_ATTR =
{
/* 0 1 2 3 4 5 6 7 */
/* ----------------------------------------- */
32, 0, 1, 12, 2, 6, 0, 13, /* 0- 7 */
3, 0, 7, 0, 0, 0, 0, 14, /* 8-15 */
10, 4, 0, 0, 8, 0, 0, 25, /* 16-23 */
0, 0, 0, 0, 0, 21, 27, 15, /* 24-31 */
31, 11, 5, 0, 0, 0, 0, 0, /* 32-39 */
9, 0, 0, 24, 0, 0, 20, 26, /* 40-47 */
30, 0, 0, 0, 0, 23, 0, 19, /* 48-55 */
29, 0, 22, 18, 28, 17, 16, 0, /* 56-63 */
};
#if !defined(CPU_COLDFIRE)
int find_first_set_bit(uint32_t val)
{
return L_ffs_table[((val & -val)*0x0450fbaf) >> 26];
}
#endif
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