atomic.h

/*
 * $Id$
 *
 * Copyright (C) 2006 kernel.org
 *
 * This file is part of opensips, a free SIP server.
 *
 * opensips 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.
 *
 * opensips 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.
 */

/*!
 * \file
 * \brief Assembler routines for atomic operations
 */

#ifndef _ATOMIC_OPS_H_
#define _ATOMIC_OPS_H_

/************************* i386 & x86_64 ARCH ****************************/
#if defined(__CPU_i386) || defined(__CPU_x86_64)

#if defined(__SMP_yes)
	#define LOCK "lock ; "
#else
	#define LOCK ""
#endif

/*! \brief
 * Make sure gcc doesn't try to be clever and move things around
 * on us. We need to use _exactly_ the address the user gave us,
 * not some alias that contains the same information.
 */
typedef struct { volatile unsigned int counter; } atomic_t;

/*! \brief
 * atomic_set - set atomic variable
 * @v: pointer of type atomic_t
 * @i: required value
 * 
 * Atomically sets the value of @v to @i.
 */ 
#define atomic_set(v,i)		(((v)->counter) = (i))

/*! \brief
 * atomic_add - add integer to atomic variable
 * @i: integer value to add
 * @v: pointer of type atomic_t
 * 
 * Atomically adds @i to @v.
 */
static __inline__ void atomic_add(int i, atomic_t *v)
{
	__asm__ __volatile__(
		LOCK "addl %1,%0"
		:"=m" (v->counter)
		:"ir" (i), "m" (v->counter));
}

/*! \brief
 * atomic_sub - subtract the atomic variable
 * @i: integer value to subtract
 * @v: pointer of type atomic_t
 * 
 * Atomically subtracts @i from @v.
 */
static __inline__ void atomic_sub(int i, atomic_t *v)
{
	__asm__ __volatile__(
		LOCK "subl %1,%0"
		:"=m" (v->counter)
		:"ir" (i), "m" (v->counter));
}

/*! \brief
 * 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 "incl %0"
		:"=m" (v->counter)
		:"m" (v->counter));
}

/*! \brief
 * atomic_dec - decrement atomic variable
 * @v: pointer of type atomic_t
 * 
 * Atomically decrements @v by 1.
 */ 
static __inline__ void atomic_dec(atomic_t *v)
{
	__asm__ __volatile__(
		LOCK "decl %0"
		:"=m" (v->counter)
		:"m" (v->counter));
}
#undef NO_ATOMIC_OPS

/************************* other ARCH ****************************/
#else

#define NO_ATOMIC_OPS

#endif

#endif