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kernel/linux-rt-4.4.41/tools/arch/x86/include/asm/atomic.h 1.29 KB
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  #ifndef _TOOLS_LINUX_ASM_X86_ATOMIC_H
  #define _TOOLS_LINUX_ASM_X86_ATOMIC_H
  
  #include <linux/compiler.h>
  #include <linux/types.h>
  #include "rmwcc.h"
  
  #define LOCK_PREFIX "
  \tlock; "
  
  /*
   * Atomic operations that C can't guarantee us.  Useful for
   * resource counting etc..
   */
  
  #define ATOMIC_INIT(i)	{ (i) }
  
  /**
   * atomic_read - read atomic variable
   * @v: pointer of type atomic_t
   *
   * Atomically reads the value of @v.
   */
  static inline int atomic_read(const atomic_t *v)
  {
  	return ACCESS_ONCE((v)->counter);
  }
  
  /**
   * atomic_set - set atomic variable
   * @v: pointer of type atomic_t
   * @i: required value
   *
   * Atomically sets the value of @v to @i.
   */
  static inline void atomic_set(atomic_t *v, int i)
  {
  	v->counter = i;
  }
  
  /**
   * atomic_inc - increment atomic variable
   * @v: pointer of type atomic_t
   *
   * Atomically increments @v by 1.
   */
  static inline void atomic_inc(atomic_t *v)
  {
  	asm volatile(LOCK_PREFIX "incl %0"
  		     : "+m" (v->counter));
  }
  
  /**
   * atomic_dec_and_test - decrement and test
   * @v: pointer of type atomic_t
   *
   * Atomically decrements @v by 1 and
   * returns true if the result is 0, or false for all other
   * cases.
   */
  static inline int atomic_dec_and_test(atomic_t *v)
  {
  	GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e");
  }
  
  #endif /* _TOOLS_LINUX_ASM_X86_ATOMIC_H */