text: /*
   * Copyright 1995, Russell King.
   * Various bits and pieces copyrights include:
   *  Linus Torvalds (test_bit).
   * Big endian support: Copyright 2001, Nicolas Pitre
   *  reworked by rmk.
   *
   * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
   *
   * Please note that the code in this file should never be included
   * from user space.  Many of these are not implemented in assembler
   * since they would be too costly.  Also, they require priviledged
   * instructions (which are not available from user mode) to ensure
   * that they are atomic.
   */
  
  #ifndef __ASM_ARM_BITOPS_H
  #define __ASM_ARM_BITOPS_H
  
  #ifdef __KERNEL__
  
  #include <asm/system.h>
  
  #define smp_mb__before_clear_bit()	do { } while (0)
  #define smp_mb__after_clear_bit()	do { } while (0)
  
  /*
   * These functions are the basis of our bit ops.
   * First, the atomic bitops.
   *
   * The endian issue for these functions is handled by the macros below.
   */
  static inline void
  ____atomic_set_bit(unsigned int bit, volatile unsigned long *p)
  {
  	unsigned long flags;
  	unsigned long mask = 1UL << (bit & 31);
  
  	p += bit >> 5;
  
  	local_irq_save(flags);
  	*p |= mask;
  	local_irq_restore(flags);
  }
  
  static inline void
  ____atomic_clear_bit(unsigned int bit, volatile unsigned long *p)
  {
  	unsigned long flags;
  	unsigned long mask = 1UL << (bit & 31);
  
  	p += bit >> 5;
  
  	local_irq_save(flags);
  	*p &= ~mask;
  	local_irq_restore(flags);
  }
  
  static inline void
  ____atomic_change_bit(unsigned int bit, volatile unsigned long *p)
  {
  	unsigned long flags;
  	unsigned long mask = 1UL << (bit & 31);
  
  	p += bit >> 5;
  
  	local_irq_save(flags);
  	*p ^= mask;
  	local_irq_restore(flags);
  }
  
  static inline int
  ____atomic_test_and_set_bit(unsigned int bit, volatile unsigned long *p)
  {
  	unsigned long flags;
  	unsigned int res;
  	unsigned long mask = 1UL << (bit & 31);
  
  	p += bit >> 5;
  
  	local_irq_save(flags);
  	res = *p;
  	*p = res | mask;
  	local_irq_restore(flags);
  
  	return res & mask;
  }
  
  static inline int
  ____atomic_test_and_clear_bit(unsigned int bit, volatile unsigned long *p)
  {
  	unsigned long flags;
  	unsigned int res;
  	unsigned long mask = 1UL << (bit & 31);
  
  	p += bit >> 5;
  
  	local_irq_save(flags);
  	res = *p;
  	*p = res & ~mask;
  	local_irq_restore(flags);
  
  	return res & mask;
  }
  
  static inline int
  ____atomic_test_and_change_bit_mask(unsigned int bit, volatile unsigned long *p)
  {
  	unsigned long flags;
  	unsigned int res;
  	unsigned long mask = 1UL << (bit & 31);
  
  	p += bit >> 5;
  
  	local_irq_save(flags);
  	res = *p;
  	*p = res ^ mask;
  	local_irq_restore(flags);
  
  	return res & mask;
  }
  
  /*
   * Now the non-atomic variants.  We let the compiler handle all
   * optimisations for these.  These are all _native_ endian.
   */
  static inline void __set_bit(int nr, volatile unsigned long *p)
  {
  	p[nr >> 5] |= (1UL << (nr & 31));
  }
  
  static inline void __clear_bit(int nr, volatile unsigned long *p)
  {
  	p[nr >> 5] &= ~(1UL << (nr & 31));
  }
  
  static inline void __change_bit(int nr, volatile unsigned long *p)
  {
  	p[nr >> 5] ^= (1UL << (nr & 31));
  }
  
  static inline int __test_and_set_bit(int nr, volatile unsigned long *p)
  {
  	unsigned long oldval, mask = 1UL << (nr & 31);
  
  	p += nr >> 5;
  
  	oldval = *p;
  	*p = oldval | mask;
  	return oldval & mask;
  }
  
  static inline int __test_and_clear_bit(int nr, volatile unsigned long *p)
  {
  	unsigned long oldval, mask = 1UL << (nr & 31);
  
  	p += nr >> 5;
  
  	oldval = *p;
  	*p = oldval & ~mask;
  
  	return oldval & mask;
  }
  
  static inline int __test_and_change_bit(int nr, volatile unsigned long *p)
  {
  	unsigned long oldval, mask = 1UL << (nr & 31);
  
  	p += nr >> 5;
  
  	oldval = *p;
  	*p = oldval ^ mask;
  
  	return oldval & mask;
  }
  
  /*
   * This routine doesn't need to be atomic.
   */
  static inline int __test_bit(int nr, const unsigned long * p)
  {
  	return p[nr >> 5] & (1UL << (nr & 31));
  }
  
  /*
   *  A note about Endian-ness.
   *  -------------------------
   *
   *          ------------ physical data bus bits -----------
   *          D31 ... D24  D23 ... D16  D15 ... D8  D7 ... D0
   *            byte 3       byte 2       byte 1      byte 0
   *
   * Note that bit 0 is defined to be 32-bit word bit 0, not byte 0 bit 0.
   */
  
  /*
   * Little endian assembly bitops.  nr = 0 -> byte 0 bit 0.
   */
  extern void _set_bit_le(int nr, volatile unsigned long * p);
  extern void _clear_bit_le(int nr, volatile unsigned long * p);
  extern void _change_bit_le(int nr, volatile unsigned long * p);
  extern int _test_and_set_bit_le(int nr, volatile unsigned long * p);
  extern int _test_and_clear_bit_le(int nr, volatile unsigned long * p);
  extern int _test_and_change_bit_le(int nr, volatile unsigned long * p);
  extern int _find_first_zero_bit_le(void * p, unsigned size);
  extern int _find_next_zero_bit_le(void * p, int size, int offset);
  
  /*
   * The __* form of bitops are non-atomic and may be reordered.
   */
  #define	ATOMIC_BITOP_LE(name,nr,p)		\
  	(__builtin_constant_p(nr) ?		\
  	 ____atomic_##name(nr, p) :		\
  	 _##name##_le(nr,p))
  
  #define	ATOMIC_BITOP_BE(name,nr,p)		\
  	(__builtin_constant_p(nr) ?		\
  	 ____atomic_##name(nr, p) :		\
  	 _##name##_be(nr,p))
  
  #define NONATOMIC_BITOP(name,nr,p)		\
  	(____nonatomic_##name(nr, p))
  
  /*
   * These are the little endian, atomic definitions.
   */
  #define set_bit(nr,p)			ATOMIC_BITOP_LE(set_bit,nr,p)
  #define clear_bit(nr,p)			ATOMIC_BITOP_LE(clear_bit,nr,p)
  #define change_bit(nr,p)		ATOMIC_BITOP_LE(change_bit,nr,p)
  #define test_and_set_bit(nr,p)		ATOMIC_BITOP_LE(test_and_set_bit,nr,p)
  #define test_and_clear_bit(nr,p)	ATOMIC_BITOP_LE(test_and_clear_bit,nr,p)
  #define test_and_change_bit(nr,p)	ATOMIC_BITOP_LE(test_and_change_bit,nr,p)
  #define test_bit(nr,p)			__test_bit(nr,p)
  #define find_first_zero_bit(p,sz)	_find_first_zero_bit_le(p,sz)
  #define find_next_zero_bit(p,sz,off)	_find_next_zero_bit_le(p,sz,off)
  
  #define WORD_BITOFF_TO_LE(x)		((x))
  
  /*
   * ffz = Find First Zero in word. Undefined if no zero exists,
   * so code should check against ~0UL first..
   */
  static inline unsigned long ffz(unsigned long word)
  {
  	int k;
  
  	word = ~word;
  	k = 31;
  	if (word & 0x0000ffff) { k -= 16; word <<= 16; }
  	if (word & 0x00ff0000) { k -= 8;  word <<= 8;  }
  	if (word & 0x0f000000) { k -= 4;  word <<= 4;  }
  	if (word & 0x30000000) { k -= 2;  word <<= 2;  }
  	if (word & 0x40000000) { k -= 1; }
          return k;
  }
  
  /*
   * ffz = Find First Zero in word. Undefined if no zero exists,
   * so code should check against ~0UL first..
   */
  static inline unsigned long __ffs(unsigned long word)
  {
  	int k;
  
  	k = 31;
  	if (word & 0x0000ffff) { k -= 16; word <<= 16; }
  	if (word & 0x00ff0000) { k -= 8;  word <<= 8;  }
  	if (word & 0x0f000000) { k -= 4;  word <<= 4;  }
  	if (word & 0x30000000) { k -= 2;  word <<= 2;  }
  	if (word & 0x40000000) { k -= 1; }
          return k;
  }
  
  /*
   * fls: find last bit set.
   */
  
  #define fls(x) generic_fls(x)
  
  /*
   * ffs: find first bit set. This is defined the same way as
   * the libc and compiler builtin ffs routines, therefore
   * differs in spirit from the above ffz (man ffs).
   */
  
  #define ffs(x) generic_ffs(x)
  
  /*
   * Find first bit set in a 168-bit bitmap, where the first
   * 128 bits are unlikely to be set.
   */
  static inline int sched_find_first_bit(unsigned long *b)
  {
  	unsigned long v;
  	unsigned int off;
  
  	for (off = 0; v = b[off], off < 4; off++) {
  		if (unlikely(v))
  			break;
  	}
  	return __ffs(v) + off * 32;
  }
  
  /*
   * hweightN: returns the hamming weight (i.e. the number
   * of bits set) of a N-bit word
   */
  
  #define hweight32(x) generic_hweight32(x)
  #define hweight16(x) generic_hweight16(x)
  #define hweight8(x) generic_hweight8(x)
  
  /*
   * Ext2 is defined to use little-endian byte ordering.
   * These do not need to be atomic.
   */
  #define ext2_set_bit(nr,p)			\
  		__test_and_set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)p)
  #define ext2_set_bit_atomic(lock,nr,p)		\
  		test_and_set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
  #define ext2_clear_bit(nr,p)			\
  		__test_and_clear_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)p)
  #define ext2_clear_bit_atomic(lock,nr,p)        \
  		test_and_clear_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)(p))
  #define ext2_test_bit(nr,p)			\
  		__test_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)p)
  #define ext2_find_first_zero_bit(p,sz)		\
  		_find_first_zero_bit_le(p,sz)
  #define ext2_find_next_zero_bit(p,sz,off)	\
  		_find_next_zero_bit_le(p,sz,off)
  
  /*
   * Minix is defined to use little-endian byte ordering.
   * These do not need to be atomic.
   */
  #define minix_set_bit(nr,p)			\
  		__set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)p)
  #define minix_test_bit(nr,p)			\
  		__test_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)p)
  #define minix_test_and_set_bit(nr,p)		\
  		__test_and_set_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)p)
  #define minix_test_and_clear_bit(nr,p)		\
  		__test_and_clear_bit(WORD_BITOFF_TO_LE(nr), (unsigned long *)p)
  #define minix_find_first_zero_bit(p,sz)		\
  		_find_first_zero_bit_le(p,sz)
  
  #endif /* __KERNEL__ */
  
  #endif /* _ARM_BITOPS_H */
  