7d9dff22e8
Add a generic __fls implementation in the same spirit as the generic __ffs one. It finds the last (most significant) set bit in the given long value. Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm> Signed-off-by: Ingo Molnar <mingo@elte.hu>
43 lines
872 B
C
43 lines
872 B
C
#ifndef _ASM_GENERIC_BITOPS___FLS_H_
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#define _ASM_GENERIC_BITOPS___FLS_H_
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#include <asm/types.h>
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/**
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* __fls - find last (most-significant) set bit in a long word
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* @word: the word to search
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*
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* Undefined if no set bit exists, so code should check against 0 first.
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*/
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static inline unsigned long __fls(unsigned long word)
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{
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int num = BITS_PER_LONG - 1;
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#if BITS_PER_LONG == 64
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if (!(word & (~0ul << 32))) {
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num -= 32;
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word <<= 32;
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}
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#endif
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if (!(word & (~0ul << (BITS_PER_LONG-16)))) {
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num -= 16;
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word <<= 16;
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}
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if (!(word & (~0ul << (BITS_PER_LONG-8)))) {
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num -= 8;
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word <<= 8;
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}
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if (!(word & (~0ul << (BITS_PER_LONG-4)))) {
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num -= 4;
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word <<= 4;
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}
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if (!(word & (~0ul << (BITS_PER_LONG-2)))) {
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num -= 2;
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word <<= 2;
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}
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if (!(word & (~0ul << (BITS_PER_LONG-1))))
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num -= 1;
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return num;
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}
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#endif /* _ASM_GENERIC_BITOPS___FLS_H_ */
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