LXR linux/tools/arch/x86/include/asm/atomic.h

   1#ifndef _TOOLS_LINUX_ASM_X86_ATOMIC_H
   2#define _TOOLS_LINUX_ASM_X86_ATOMIC_H
   3
   4#include <linux/compiler.h>
   5#include <linux/types.h>
   6#include "rmwcc.h"
   7
   8#define LOCK_PREFIX "\n\tlock; "
   9
  10/*
  11 * Atomic operations that C can't guarantee us.  Useful for
  12 * resource counting etc..
  13 */
  14
  15#define ATOMIC_INIT(i)  { (i) }
  16
  17/**
  18 * atomic_read - read atomic variable
  19 * @v: pointer of type atomic_t
  20 *
  21 * Atomically reads the value of @v.
  22 */
  23static inline int atomic_read(const atomic_t *v)
  24{
  25        return ACCESS_ONCE((v)->counter);
  26}
  27
  28/**
  29 * atomic_set - set atomic variable
  30 * @v: pointer of type atomic_t
  31 * @i: required value
  32 *
  33 * Atomically sets the value of @v to @i.
  34 */
  35static inline void atomic_set(atomic_t *v, int i)
  36{
  37        v->counter = i;
  38}
  39
  40/**
  41 * atomic_inc - increment atomic variable
  42 * @v: pointer of type atomic_t
  43 *
  44 * Atomically increments @v by 1.
  45 */
  46static inline void atomic_inc(atomic_t *v)
  47{
  48        asm volatile(LOCK_PREFIX "incl %0"
  49                     : "+m" (v->counter));
  50}
  51
  52/**
  53 * atomic_dec_and_test - decrement and test
  54 * @v: pointer of type atomic_t
  55 *
  56 * Atomically decrements @v by 1 and
  57 * returns true if the result is 0, or false for all other
  58 * cases.
  59 */
  60static inline int atomic_dec_and_test(atomic_t *v)
  61{
  62        GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e");
  63}
  64
  65#endif /* _TOOLS_LINUX_ASM_X86_ATOMIC_H */
  66