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44 lines
920 B
44 lines
920 B
/* SPDX-License-Identifier: GPL-2.0 */ |
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#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 __always_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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