// ============================================================================
// Copyright (c) 2010 Faustino Frechilla
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
/// @file lock_free_atomic_ops.h
/// @brief This file contains functions to wrap the built-in atomic operations 
///        defined for your compiler
///
/// @author Faustino Frechilla
/// @history
/// Ref  Who                 When         What
///      Faustino Frechilla  11-Jul-2010  Original development. GCC support
///      Faustino Frechilla  08-Aug-2014  Change to MIT license
/// @endhistory
/// 
// ============================================================================

#ifndef __ATOMIC_OPS_H
#define __ATOMIC_OPS_H

#ifdef __GNUC__
// Atomic functions in GCC are present from version 4.1.0 on
// http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html

// Test for GCC >= 4.1.0
#if (__GNUC__ < 4) || \
    ((__GNUC__ == 4) && ((__GNUC_MINOR__ < 1) || \
                        ((__GNUC_MINOR__     == 1) && \
                         (__GNUC_PATCHLEVEL__ < 0))) )
                        
#error Atomic built-in functions are only available in GCC in versions >= 4.1.0

#endif // end of check for GCC 4.1.0

/// @brief atomically adds a_count to the variable pointed by a_ptr
/// @return the value that had previously been in memory
#define AtomicAdd(a_ptr,a_count) __sync_fetch_and_add (a_ptr, a_count)

/// @brief atomically substracts a_count from the variable pointed by a_ptr
/// @return the value that had previously been in memory
#define AtomicSub(a_ptr,a_count) __sync_fetch_and_sub (a_ptr, a_count)

/// @brief Compare And Swap
///        If the current value of *a_ptr is a_oldVal, then write a_newVal into *a_ptr
/// @return true if the comparison is successful and a_newVal was written
#define CAS(a_ptr, a_oldVal, a_newVal) __sync_bool_compare_and_swap(a_ptr, a_oldVal, a_newVal)

/// @brief Compare And Swap
///        If the current value of *a_ptr is a_oldVal, then write a_newVal into *a_ptr
/// @return the contents of *a_ptr before the operation
#define CASVal(a_ptr, a_oldVal, a_newVal) __sync_val_compare_and_swap(a_ptr, a_oldVal, a_newVal)

#else
#error Atomic functions such as CAS or AtomicAdd are not defined for your compiler. Please add them in atomic_ops.h
#endif // __GNUC__

#endif // __ATOMIC_OPS_H