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| File: [Development] / linux-2.6-xfs / include / asm-generic / bitops / __fls.h (download)
Revision 1.1, Mon Aug 4 17:03:13 2008 UTC (9 years, 2 months ago) by lachlan.longdrop.melbourne.sgi.com
Merge up to 2.6.26 Merge of 2.6.x-xfs-melb:linux:31804b by kenmcd. |
#ifndef _ASM_GENERIC_BITOPS___FLS_H_
#define _ASM_GENERIC_BITOPS___FLS_H_
#include <asm/types.h>
/**
* __fls - find last (most-significant) set bit in a long word
* @word: the word to search
*
* Undefined if no set bit exists, so code should check against 0 first.
*/
static inline unsigned long __fls(unsigned long word)
{
int num = BITS_PER_LONG - 1;
#if BITS_PER_LONG == 64
if (!(word & (~0ul << 32))) {
num -= 32;
word <<= 32;
}
#endif
if (!(word & (~0ul << (BITS_PER_LONG-16)))) {
num -= 16;
word <<= 16;
}
if (!(word & (~0ul << (BITS_PER_LONG-8)))) {
num -= 8;
word <<= 8;
}
if (!(word & (~0ul << (BITS_PER_LONG-4)))) {
num -= 4;
word <<= 4;
}
if (!(word & (~0ul << (BITS_PER_LONG-2)))) {
num -= 2;
word <<= 2;
}
if (!(word & (~0ul << (BITS_PER_LONG-1))))
num -= 1;
return num;
}
#endif /* _ASM_GENERIC_BITOPS___FLS_H_ */