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kernel/linux-imx6_3.14.28/include/asm-generic/bitops/non-atomic.h 2.96 KB
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  #ifndef _ASM_GENERIC_BITOPS_NON_ATOMIC_H_
  #define _ASM_GENERIC_BITOPS_NON_ATOMIC_H_
  
  #include <asm/types.h>
  
  /**
   * __set_bit - Set a bit in memory
   * @nr: the bit to set
   * @addr: the address to start counting from
   *
   * Unlike set_bit(), this function is non-atomic and may be reordered.
   * If it's called on the same region of memory simultaneously, the effect
   * may be that only one operation succeeds.
   */
  static inline void __set_bit(int nr, volatile unsigned long *addr)
  {
  	unsigned long mask = BIT_MASK(nr);
  	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
  
  	*p  |= mask;
  }
  
  static inline void __clear_bit(int nr, volatile unsigned long *addr)
  {
  	unsigned long mask = BIT_MASK(nr);
  	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
  
  	*p &= ~mask;
  }
  
  /**
   * __change_bit - Toggle a bit in memory
   * @nr: the bit to change
   * @addr: the address to start counting from
   *
   * Unlike change_bit(), this function is non-atomic and may be reordered.
   * If it's called on the same region of memory simultaneously, the effect
   * may be that only one operation succeeds.
   */
  static inline void __change_bit(int nr, volatile unsigned long *addr)
  {
  	unsigned long mask = BIT_MASK(nr);
  	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
  
  	*p ^= mask;
  }
  
  /**
   * __test_and_set_bit - Set a bit and return its old value
   * @nr: Bit to set
   * @addr: Address to count from
   *
   * This operation is non-atomic and can be reordered.
   * If two examples of this operation race, one can appear to succeed
   * but actually fail.  You must protect multiple accesses with a lock.
   */
  static inline int __test_and_set_bit(int nr, volatile unsigned long *addr)
  {
  	unsigned long mask = BIT_MASK(nr);
  	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
  	unsigned long old = *p;
  
  	*p = old | mask;
  	return (old & mask) != 0;
  }
  
  /**
   * __test_and_clear_bit - Clear a bit and return its old value
   * @nr: Bit to clear
   * @addr: Address to count from
   *
   * This operation is non-atomic and can be reordered.
   * If two examples of this operation race, one can appear to succeed
   * but actually fail.  You must protect multiple accesses with a lock.
   */
  static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr)
  {
  	unsigned long mask = BIT_MASK(nr);
  	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
  	unsigned long old = *p;
  
  	*p = old & ~mask;
  	return (old & mask) != 0;
  }
  
  /* WARNING: non atomic and it can be reordered! */
  static inline int __test_and_change_bit(int nr,
  					    volatile unsigned long *addr)
  {
  	unsigned long mask = BIT_MASK(nr);
  	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
  	unsigned long old = *p;
  
  	*p = old ^ mask;
  	return (old & mask) != 0;
  }
  
  /**
   * test_bit - Determine whether a bit is set
   * @nr: bit number to test
   * @addr: Address to start counting from
   */
  static inline int test_bit(int nr, const volatile unsigned long *addr)
  {
  	return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
  }
  
  #endif /* _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ */