tools/testing/selftests/futex/include/atomic.h

   1 /******************************************************************************
   2  *
   3  *   Copyright © International Business Machines  Corp., 2009
   4  *
   5  *   This program is free software;  you can redistribute it and/or modify
   6  *   it under the terms of the GNU General Public License as published by
   7  *   the Free Software Foundation; either version 2 of the License, or
   8  *   (at your option) any later version.
   9  *
  10  * DESCRIPTION
  11  *      GCC atomic builtin wrappers
  12  *      http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
  13  *
  14  * AUTHOR
  15  *      Darren Hart <dvhart@linux.intel.com>
  16  *
  17  * HISTORY
  18  *      2009-Nov-17: Initial version by Darren Hart <dvhart@linux.intel.com>
  19  *
  20  *****************************************************************************/
  21
  22 #ifndef _ATOMIC_H
  23 #define _ATOMIC_H
  24
  25 typedef struct {
  26         volatile int val;
  27 } atomic_t;
  28
  29 #define ATOMIC_INITIALIZER { 0 }
  30
  31 /**
  32  * atomic_cmpxchg() - Atomic compare and exchange
  33  * @uaddr:      The address of the futex to be modified
  34  * @oldval:     The expected value of the futex
  35  * @newval:     The new value to try and assign the futex
  36  *
  37  * Return the old value of addr->val.
  38  */
  39 static inline int
  40 atomic_cmpxchg(atomic_t *addr, int oldval, int newval)
  41 {
  42         return __sync_val_compare_and_swap(&addr->val, oldval, newval);
  43 }
  44
  45 /**
  46  * atomic_inc() - Atomic incrememnt
  47  * @addr:       Address of the variable to increment
  48  *
  49  * Return the new value of addr->val.
  50  */
  51 static inline int
  52 atomic_inc(atomic_t *addr)
  53 {
  54         return __sync_add_and_fetch(&addr->val, 1);
  55 }
  56
  57 /**
  58  * atomic_dec() - Atomic decrement
  59  * @addr:       Address of the variable to decrement
  60  *
  61  * Return the new value of addr-val.
  62  */
  63 static inline int
  64 atomic_dec(atomic_t *addr)
  65 {
  66         return __sync_sub_and_fetch(&addr->val, 1);
  67 }
  68
  69 /**
  70  * atomic_set() - Atomic set
  71  * @addr:       Address of the variable to set
  72  * @newval:     New value for the atomic_t
  73  *
  74  * Return the new value of addr->val.
  75  */
  76 static inline int
  77 atomic_set(atomic_t *addr, int newval)
  78 {
  79         addr->val = newval;
  80         return newval;
  81 }
  82
  83 #endif