/*
 * This file is part of the coreboot project.
 *
 * 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; version 2 of the License.
 *
 * 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.
 */

#ifndef ARCH_SMP_ATOMIC_H
#define ARCH_SMP_ATOMIC_H

/*
 * 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 int counter; } atomic_t;

#define ATOMIC_INIT(i)	{ (i) }

/** @file x86/include/arch/smp/atomic.h
 *
 * Atomic operations that C can't guarantee us.  Useful for
 * resource counting etc..
 */

/**
 * atomic_read - read atomic variable
 * @param v: pointer of type atomic_t
 *
 * Atomically reads the value of v.  Note that the guaranteed
 * useful range of an atomic_t is only 24 bits.
 */
#define atomic_read(v)		((v)->counter)

/**
 * atomic_set - set atomic variable
 * @param v: pointer of type atomic_t
 * @param i: required value
 *
 * Atomically sets the value of v to i.  Note that the guaranteed
 * useful range of an atomic_t is only 24 bits.
 */
#define atomic_set(v, i)	(((v)->counter) = (i))

/**
 * atomic_inc - increment atomic variable
 * @param v: pointer of type atomic_t
 *
 * Atomically increments v by 1.  Note that the guaranteed
 * useful range of an atomic_t is only 24 bits.
 */
static inline __attribute__((always_inline)) void atomic_inc(atomic_t *v)
{
	__asm__ __volatile__(
		"lock ; incl %0"
		: "=m" (v->counter)
		: "m" (v->counter));
}

/**
 * atomic_dec - decrement atomic variable
 * @param v: pointer of type atomic_t
 *
 * Atomically decrements v by 1.  Note that the guaranteed
 * useful range of an atomic_t is only 24 bits.
 */
static inline __attribute__((always_inline)) void atomic_dec(atomic_t *v)
{
	__asm__ __volatile__(
		"lock ; decl %0"
		: "=m" (v->counter)
		: "m" (v->counter));
}



#endif /* ARCH_SMP_ATOMIC_H */
