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kernel/linux-rt-4.4.41/tools/testing/selftests/futex/include/atomic.h 1.95 KB
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  /******************************************************************************
   *
   *   Copyright © International Business Machines  Corp., 2009
   *
   *   This program is free software;  you can redistribute it and/or modify
   *   it under the terms of the GNU General Public License as published by
   *   the Free Software Foundation; either version 2 of the License, or
   *   (at your option) any later version.
   *
   * DESCRIPTION
   *      GCC atomic builtin wrappers
   *      http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
   *
   * AUTHOR
   *      Darren Hart <dvhart@linux.intel.com>
   *
   * HISTORY
   *      2009-Nov-17: Initial version by Darren Hart <dvhart@linux.intel.com>
   *
   *****************************************************************************/
  
  #ifndef _ATOMIC_H
  #define _ATOMIC_H
  
  typedef struct {
  	volatile int val;
  } atomic_t;
  
  #define ATOMIC_INITIALIZER { 0 }
  
  /**
   * atomic_cmpxchg() - Atomic compare and exchange
   * @uaddr:	The address of the futex to be modified
   * @oldval:	The expected value of the futex
   * @newval:	The new value to try and assign the futex
   *
   * Return the old value of addr->val.
   */
  static inline int
  atomic_cmpxchg(atomic_t *addr, int oldval, int newval)
  {
  	return __sync_val_compare_and_swap(&addr->val, oldval, newval);
  }
  
  /**
   * atomic_inc() - Atomic incrememnt
   * @addr:	Address of the variable to increment
   *
   * Return the new value of addr->val.
   */
  static inline int
  atomic_inc(atomic_t *addr)
  {
  	return __sync_add_and_fetch(&addr->val, 1);
  }
  
  /**
   * atomic_dec() - Atomic decrement
   * @addr:	Address of the variable to decrement
   *
   * Return the new value of addr-val.
   */
  static inline int
  atomic_dec(atomic_t *addr)
  {
  	return __sync_sub_and_fetch(&addr->val, 1);
  }
  
  /**
   * atomic_set() - Atomic set
   * @addr:	Address of the variable to set
   * @newval:	New value for the atomic_t
   *
   * Return the new value of addr->val.
   */
  static inline int
  atomic_set(atomic_t *addr, int newval)
  {
  	addr->val = newval;
  	return newval;
  }
  
  #endif