tools/include/asm-generic/atomic-gcc.h

   1 #ifndef __TOOLS_ASM_GENERIC_ATOMIC_H
   2 #define __TOOLS_ASM_GENERIC_ATOMIC_H
   3
   4 #include <linux/compiler.h>
   5 #include <linux/types.h>
   6
   7 /*
   8  * Atomic operations that C can't guarantee us.  Useful for
   9  * resource counting etc..
  10  *
  11  * Excerpts obtained from the Linux kernel sources.
  12  */
  13
  14 #define ATOMIC_INIT(i)  { (i) }
  15
  16 /**
  17  * atomic_read - read atomic variable
  18  * @v: pointer of type atomic_t
  19  *
  20  * Atomically reads the value of @v.
  21  */
  22 static inline int atomic_read(const atomic_t *v)
  23 {
  24         return ACCESS_ONCE((v)->counter);
  25 }
  26
  27 /**
  28  * atomic_set - set atomic variable
  29  * @v: pointer of type atomic_t
  30  * @i: required value
  31  *
  32  * Atomically sets the value of @v to @i.
  33  */
  34 static inline void atomic_set(atomic_t *v, int i)
  35 {
  36         v->counter = i;
  37 }
  38
  39 /**
  40  * atomic_inc - increment atomic variable
  41  * @v: pointer of type atomic_t
  42  *
  43  * Atomically increments @v by 1.
  44  */
  45 static inline void atomic_inc(atomic_t *v)
  46 {
  47         __sync_add_and_fetch(&v->counter, 1);
  48 }
  49
  50 /**
  51  * atomic_dec_and_test - decrement and test
  52  * @v: pointer of type atomic_t
  53  *
  54  * Atomically decrements @v by 1 and
  55  * returns true if the result is 0, or false for all other
  56  * cases.
  57  */
  58 static inline int atomic_dec_and_test(atomic_t *v)
  59 {
  60         return __sync_sub_and_fetch(&v->counter, 1) == 0;
  61 }
  62
  63 #define cmpxchg(ptr, oldval, newval) \
  64         __sync_val_compare_and_swap(ptr, oldval, newval)
  65
  66 static inline int atomic_cmpxchg(atomic_t *v, int oldval, int newval)
  67 {
  68         return cmpxchg(&(v)->counter, oldval, newval);
  69 }
  70
  71 #endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */