| /****************************************************************************** |
| * |
| * 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 |
