LXR linux/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 */
  22static 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 */
  34static 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 */
  45static 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 */
  58static inline int atomic_dec_and_test(atomic_t *v)
  59{
  60        return __sync_sub_and_fetch(&v->counter, 1) == 0;
  61}
  62
  63#endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */
  64