/*

 * Copyright (C) 2013 Red Hat, Inc.

 *

 * Author: Angus Salkeld <asalkeld@redhat.com>

 *

 * libqb is free software: you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation, either version 2.1 of the License, or

 * (at your option) any later version.

 *

 * libqb 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 Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with libqb.  If not, see <http://www.gnu.org/licenses/>.

 */

#ifndef QB_ATOMIC_INT_H_DEFINED

#define QB_ATOMIC_INT_H_DEFINED

/*

 * This adds some extra atomic functionality, building on the

 * gcc atomic builtins.

 */

#include "os_base.h"

#include <qb/qbdefs.h>

#include <qb/qbatomic.h>

/* This is a thin wrapper around the new gcc atomics.

 */

enum qb_atomic_model {

	QB_ATOMIC_RELAXED,

	QB_ATOMIC_CONSUME,

	QB_ATOMIC_ACQUIRE,

	QB_ATOMIC_RELEASE,

	QB_ATOMIC_ACQ_REL,

	QB_ATOMIC_SEQ_CST,

};

#ifdef HAVE_GCC_BUILTINS_FOR_ATOMIC_OPERATIONS

static inline int

qb_model_map(enum qb_atomic_model model)

{

	switch (model) {

	case QB_ATOMIC_ACQUIRE:

		return __ATOMIC_ACQUIRE;

	case QB_ATOMIC_RELEASE:

		return __ATOMIC_RELEASE;

	case QB_ATOMIC_RELAXED:

		return __ATOMIC_RELAXED;

	case QB_ATOMIC_CONSUME:

		return __ATOMIC_CONSUME;

	case QB_ATOMIC_ACQ_REL:

		return __ATOMIC_ACQ_REL;

	case QB_ATOMIC_SEQ_CST:

	default:

		return __ATOMIC_SEQ_CST;

	}

}

#endif /* HAVE_GCC_BUILTINS_FOR_ATOMIC_OPERATIONS */

#ifdef QB_ATOMIC_OP_MEMORY_BARRIER_NEEDED

#ifdef HAVE_GCC_BUILTINS_FOR_SYNC_OPERATIONS

#define QB_ATOMIC_MEMORY_BARRIER __sync_synchronize ()

#else

#ifndef HAVE_GCC_BUILTINS_FOR_ATOMIC_OPERATIONS

#warning you need memory barriers but do not have an implementation.

#endif /* HAVE_GCC_BUILTINS_FOR_ATOMIC_OPERATIONS */

#endif /* HAVE_GCC_BUILTINS_FOR_SYNC_OPERATIONS */

#ifndef QB_ATOMIC_MEMORY_BARRIER

#define QB_ATOMIC_MEMORY_BARRIER

#endif /* QB_ATOMIC_MEMORY_BARRIER */

#endif /* QB_ATOMIC_OP_MEMORY_BARRIER_NEEDED */

/**

 * Reads the value of the integer pointed to by atomic.

 * Also acts as a memory barrier.

 *

 * @param atomic a pointer to an integer

 * @param model the memory model to use.

 *

 * @return the value of atomic

 */

static inline int32_t

qb_atomic_int_get_ex(volatile int32_t QB_GNUC_MAY_ALIAS * atomic,

		     enum qb_atomic_model model)

{

#ifdef HAVE_GCC_BUILTINS_FOR_ATOMIC_OPERATIONS

	return __atomic_load_n(atomic, qb_model_map(model));

#else

	return qb_atomic_int_get(atomic);

#endif

}

/**

 * Sets the value of the integer pointed to by atomic.

 * Also acts as a memory barrier.

 *

 * @param atomic a pointer to an integer

 * @param newval the new value

 * @param model the memory model to use.

 */

static inline void

qb_atomic_int_set_ex(volatile int32_t QB_GNUC_MAY_ALIAS * atomic,

		     int32_t newval,

		     enum qb_atomic_model model)

{

#ifdef HAVE_GCC_BUILTINS_FOR_ATOMIC_OPERATIONS

	__atomic_store_n(atomic, newval, qb_model_map(model));

#else

/*

 * If the model is acquire we need the barrier afterwards,

 * and if its cst we need it before and after.

 * Note: qb_atomic_int_set already has a memory barrier after

 * the set.

 */

	if (model != QB_ATOMIC_RELAXED && model != QB_ATOMIC_CONSUME) {

		QB_ATOMIC_MEMORY_BARRIER;

	}

	qb_atomic_int_set(atomic, newval);

#endif

}

#endif /* QB_ATOMIC_INT_H_DEFINED */