include/asm-generic/bitops/non-atomic.h

   1 #ifndef _ASM_GENERIC_BITOPS_NON_ATOMIC_H_
   2 #define _ASM_GENERIC_BITOPS_NON_ATOMIC_H_
   3
   4 #include <asm/types.h>
   5
   6 #define BITOP_MASK(nr)          (1UL << ((nr) % BITS_PER_LONG))
   7 #define BITOP_WORD(nr)          ((nr) / BITS_PER_LONG)
   8
   9 /**
  10  * __set_bit - Set a bit in memory
  11  * @nr: the bit to set
  12  * @addr: the address to start counting from
  13  *
  14  * Unlike set_bit(), this function is non-atomic and may be reordered.
  15  * If it's called on the same region of memory simultaneously, the effect
  16  * may be that only one operation succeeds.
  17  */
  18 static inline void __set_bit(int nr, volatile unsigned long *addr)
  19 {
  20         unsigned long mask = BITOP_MASK(nr);
  21         unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
  22
  23         *p  |= mask;
  24 }
  25
  26 static inline void __clear_bit(int nr, volatile unsigned long *addr)
  27 {
  28         unsigned long mask = BITOP_MASK(nr);
  29         unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
  30
  31         *p &= ~mask;
  32 }
  33
  34 /**
  35  * __change_bit - Toggle a bit in memory
  36  * @nr: the bit to change
  37  * @addr: the address to start counting from
  38  *
  39  * Unlike change_bit(), this function is non-atomic and may be reordered.
  40  * If it's called on the same region of memory simultaneously, the effect
  41  * may be that only one operation succeeds.
  42  */
  43 static inline void __change_bit(int nr, volatile unsigned long *addr)
  44 {
  45         unsigned long mask = BITOP_MASK(nr);
  46         unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
  47
  48         *p ^= mask;
  49 }
  50
  51 /**
  52  * __test_and_set_bit - Set a bit and return its old value
  53  * @nr: Bit to set
  54  * @addr: Address to count from
  55  *
  56  * This operation is non-atomic and can be reordered.
  57  * If two examples of this operation race, one can appear to succeed
  58  * but actually fail.  You must protect multiple accesses with a lock.
  59  */
  60 static inline int __test_and_set_bit(int nr, volatile unsigned long *addr)
  61 {
  62         unsigned long mask = BITOP_MASK(nr);
  63         unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
  64         unsigned long old = *p;
  65
  66         *p = old | mask;
  67         return (old & mask) != 0;
  68 }
  69
  70 /**
  71  * __test_and_clear_bit - Clear a bit and return its old value
  72  * @nr: Bit to clear
  73  * @addr: Address to count from
  74  *
  75  * This operation is non-atomic and can be reordered.
  76  * If two examples of this operation race, one can appear to succeed
  77  * but actually fail.  You must protect multiple accesses with a lock.
  78  */
  79 static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr)
  80 {
  81         unsigned long mask = BITOP_MASK(nr);
  82         unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
  83         unsigned long old = *p;
  84
  85         *p = old & ~mask;
  86         return (old & mask) != 0;
  87 }
  88
  89 /* WARNING: non atomic and it can be reordered! */
  90 static inline int __test_and_change_bit(int nr,
  91                                             volatile unsigned long *addr)
  92 {
  93         unsigned long mask = BITOP_MASK(nr);
  94         unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr);
  95         unsigned long old = *p;
  96
  97         *p = old ^ mask;
  98         return (old & mask) != 0;
  99 }
 100
 101 /**
 102  * test_bit - Determine whether a bit is set
 103  * @nr: bit number to test
 104  * @addr: Address to start counting from
 105  */
 106 static inline int test_bit(int nr, const volatile unsigned long *addr)
 107 {
 108         return 1UL & (addr[BITOP_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
 109 }
 110
 111 #endif /* _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ */