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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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
* the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* NAME
* atomic.h
*
* DESCRIPTION
* GCC atomic builtin wrappers
* http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
*
* AUTHOR
* Darren Hart <dvhltc@us.ibm.com>
*
* HISTORY
* 2009-Nov-17: Initial version by Darren Hart <dvhltc@us.ibm.com>
*
*****************************************************************************/
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
*
* Implement cmpxchg using gcc atomic builtins.
*/
static inline void
atomic_cmpxchg(atomic_t *addr, int oldval, int newval)
{
__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;
*/
static inline void
atomic_inc(atomic_t *addr)
{
__sync_add_and_fetch(&addr->val, 1);
}
/**
* atomic_dec() - Atomic decrement
* @addr: Address of the variable to decrement
*
* Return the new value of *addr;
*/
static inline void
atomic_dec(atomic_t *addr)
{
__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;
*/
static inline void
atomic_set(atomic_t *addr, int newval)
{
addr->val = newval;
}