text: #ifndef _LINUX_BITOPS_H
  #define _LINUX_BITOPS_H
  #include <asm/types.h>
  
  #ifdef	__KERNEL__
  #define BIT(nr)			(1UL << (nr))
  #define BIT_MASK(nr)		(1UL << ((nr) % BITS_PER_LONG))
  #define BIT_WORD(nr)		((nr) / BITS_PER_LONG)
  #define BITS_PER_BYTE		8
  #define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
  #endif
  
  /*
   * Include this here because some architectures need generic_ffs/fls in
   * scope
   */
  #include <asm/bitops.h>
  
  #define for_each_set_bit(bit, addr, size) \
  	for ((bit) = find_first_bit((addr), (size)); \
  	     (bit) < (size); \
  	     (bit) = find_next_bit((addr), (size), (bit) + 1))
  
  static __inline__ int get_bitmask_order(unsigned int count)
  {
  	int order;
  
  	order = fls(count);
  	return order;	/* We could be slightly more clever with -1 here... */
  }
  
  static __inline__ int get_count_order(unsigned int count)
  {
  	int order;
  
  	order = fls(count) - 1;
  	if (count & (count - 1))
  		order++;
  	return order;
  }
  
  static inline unsigned long hweight_long(unsigned long w)
  {
  	return sizeof(w) == 4 ? hweight32(w) : hweight64(w);
  }
  
  /*
   * Clearly slow versions of the hweightN() functions, their benefit is
   * of course compile time evaluation of constant arguments.
   */
  #define HWEIGHT8(w)					\
        (	BUILD_BUG_ON_ZERO(!__builtin_constant_p(w)) +	\
  	(!!((w) & (1ULL << 0))) +			\
  	(!!((w) & (1ULL << 1))) +			\
  	(!!((w) & (1ULL << 2))) +			\
  	(!!((w) & (1ULL << 3))) +			\
  	(!!((w) & (1ULL << 4))) +			\
  	(!!((w) & (1ULL << 5))) +			\
  	(!!((w) & (1ULL << 6))) +			\
  	(!!((w) & (1ULL << 7)))	)
  
  #define HWEIGHT16(w) (HWEIGHT8(w)  + HWEIGHT8((w) >> 8))
  #define HWEIGHT32(w) (HWEIGHT16(w) + HWEIGHT16((w) >> 16))
  #define HWEIGHT64(w) (HWEIGHT32(w) + HWEIGHT32((w) >> 32))
  
  /*
   * Type invariant version that simply casts things to the
   * largest type.
   */
  #define HWEIGHT(w)   HWEIGHT64((u64)(w))
  
  /**
   * rol32 - rotate a 32-bit value left
   * @word: value to rotate
   * @shift: bits to roll
   */
  static inline __u32 rol32(__u32 word, unsigned int shift)
  {
  	return (word << shift) | (word >> (32 - shift));
  }
  
  /**
   * ror32 - rotate a 32-bit value right
   * @word: value to rotate
   * @shift: bits to roll
   */
  static inline __u32 ror32(__u32 word, unsigned int shift)
  {
  	return (word >> shift) | (word << (32 - shift));
  }
  
  /**
   * rol16 - rotate a 16-bit value left
   * @word: value to rotate
   * @shift: bits to roll
   */
  static inline __u16 rol16(__u16 word, unsigned int shift)
  {
  	return (word << shift) | (word >> (16 - shift));
  }
  
  /**
   * ror16 - rotate a 16-bit value right
   * @word: value to rotate
   * @shift: bits to roll
   */
  static inline __u16 ror16(__u16 word, unsigned int shift)
  {
  	return (word >> shift) | (word << (16 - shift));
  }
  
  /**
   * rol8 - rotate an 8-bit value left
   * @word: value to rotate
   * @shift: bits to roll
   */
  static inline __u8 rol8(__u8 word, unsigned int shift)
  {
  	return (word << shift) | (word >> (8 - shift));
  }
  
  /**
   * ror8 - rotate an 8-bit value right
   * @word: value to rotate
   * @shift: bits to roll
   */
  static inline __u8 ror8(__u8 word, unsigned int shift)
  {
  	return (word >> shift) | (word << (8 - shift));
  }
  
  static inline unsigned fls_long(unsigned long l)
  {
  	if (sizeof(l) == 4)
  		return fls(l);
  	return fls64(l);
  }
  
  /**
   * __ffs64 - find first set bit in a 64 bit word
   * @word: The 64 bit word
   *
   * On 64 bit arches this is a synomyn for __ffs
   * The result is not defined if no bits are set, so check that @word
   * is non-zero before calling this.
   */
  static inline unsigned long __ffs64(u64 word)
  {
  #if BITS_PER_LONG == 32
  	if (((u32)word) == 0UL)
  		return __ffs((u32)(word >> 32)) + 32;
  #elif BITS_PER_LONG != 64
  #error BITS_PER_LONG not 32 or 64
  #endif
  	return __ffs((unsigned long)word);
  }
  
  #ifdef __KERNEL__
  #ifdef CONFIG_GENERIC_FIND_FIRST_BIT
  
  /**
   * find_first_bit - find the first set bit in a memory region
   * @addr: The address to start the search at
   * @size: The maximum size to search
   *
   * Returns the bit number of the first set bit.
   */
  extern unsigned long find_first_bit(const unsigned long *addr,
  				    unsigned long size);
  
  /**
   * find_first_zero_bit - find the first cleared bit in a memory region
   * @addr: The address to start the search at
   * @size: The maximum size to search
   *
   * Returns the bit number of the first cleared bit.
   */
  extern unsigned long find_first_zero_bit(const unsigned long *addr,
  					 unsigned long size);
  #endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
  
  #ifdef CONFIG_GENERIC_FIND_LAST_BIT
  /**
   * find_last_bit - find the last set bit in a memory region
   * @addr: The address to start the search at
   * @size: The maximum size to search
   *
   * Returns the bit number of the first set bit, or size.
   */
  extern unsigned long find_last_bit(const unsigned long *addr,
  				   unsigned long size);
  #endif /* CONFIG_GENERIC_FIND_LAST_BIT */
  
  #ifdef CONFIG_GENERIC_FIND_NEXT_BIT
  
  /**
   * find_next_bit - find the next set bit in a memory region
   * @addr: The address to base the search on
   * @offset: The bitnumber to start searching at
   * @size: The bitmap size in bits
   */
  extern unsigned long find_next_bit(const unsigned long *addr,
  				   unsigned long size, unsigned long offset);
  
  /**
   * find_next_zero_bit - find the next cleared bit in a memory region
   * @addr: The address to base the search on
   * @offset: The bitnumber to start searching at
   * @size: The bitmap size in bits
   */
  
  extern unsigned long find_next_zero_bit(const unsigned long *addr,
  					unsigned long size,
  					unsigned long offset);
  
  #endif /* CONFIG_GENERIC_FIND_NEXT_BIT */
  #endif /* __KERNEL__ */
  #endif
  