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#include
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#include
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#include
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#include
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/*
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 * deal with unrepresentable constant logarithms
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 */
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extern __attribute__((const, noreturn))
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int ____ilog2_NaN(void);
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/*
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/*
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 * non-constant log of base 2 calculators
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 * non-constant log of base 2 calculators
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 * - the arch may override these in asm/bitops.h if they can be implemented
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 * - the arch may override these in asm/bitops.h if they can be implemented
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 *   more efficiently than using fls() and fls64()
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 *   more efficiently than using fls() and fls64()
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 * selects the appropriately-sized optimised version depending on sizeof(n)
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 * selects the appropriately-sized optimised version depending on sizeof(n)
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 */
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 */
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#define ilog2(n)				\
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#define ilog2(n)				\
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(						\
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(						\
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	__builtin_constant_p(n) ? (		\
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	__builtin_constant_p(n) ? (		\
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		(n) < 2 ? 0 :			\
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		(n) < 1 ? ____ilog2_NaN() :	\
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		(n) & (1ULL << 63) ? 63 :	\
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		(n) & (1ULL << 63) ? 63 :	\
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		(n) & (1ULL << 62) ? 62 :	\
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		(n) & (1ULL << 62) ? 62 :	\
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		(n) & (1ULL << 61) ? 61 :	\
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		(n) & (1ULL << 61) ? 61 :	\
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		(n) & (1ULL << 60) ? 60 :	\
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		(n) & (1ULL << 60) ? 60 :	\
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		(n) & (1ULL << 59) ? 59 :	\
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		(n) & (1ULL << 59) ? 59 :	\
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		(n) & (1ULL <<  6) ?  6 :	\
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		(n) & (1ULL <<  6) ?  6 :	\
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		(n) & (1ULL <<  5) ?  5 :	\
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		(n) & (1ULL <<  5) ?  5 :	\
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		(n) & (1ULL <<  4) ?  4 :	\
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		(n) & (1ULL <<  4) ?  4 :	\
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		(n) & (1ULL <<  3) ?  3 :	\
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		(n) & (1ULL <<  3) ?  3 :	\
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		(n) & (1ULL <<  2) ?  2 :	\
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		(n) & (1ULL <<  2) ?  2 :	\
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		(n) & (1ULL <<  1) ?  1 :	\
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		(n) & (1ULL <<  0) ?  0 :	\
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		____ilog2_NaN()			\
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		1 ) :				\
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				   ) :		\
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	(sizeof(n) <= 4) ?			\
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	(sizeof(n) <= 4) ?			\
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	__ilog2_u32(n) :			\
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	__ilog2_u32(n) :			\
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	__ilog2_u64(n)				\
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	__ilog2_u64(n)				\
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 )
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 )
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 *  ob2(4) = 2
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 *  ob2(4) = 2
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 *  ob2(5) = 3
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 *  ob2(5) = 3
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 *  ... and so on.
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 *  ... and so on.
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 */
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 */
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static inline __attribute_const__
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int __order_base_2(unsigned long n)
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{
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	return n > 1 ? ilog2(n - 1) + 1 : 0;
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}
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#define order_base_2(n)				\
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(						\
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	__builtin_constant_p(n) ? (		\
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		((n) == 0 || (n) == 1) ? 0 :	\
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		ilog2((n) - 1) + 1) :		\
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	__order_base_2(n)			\
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#define order_base_2(n) ilog2(roundup_pow_of_two(n))