#ifndef UC_ATOMIC_H_
#define UC_ATOMIC_H_

/** @file
 * Atomic functions (macros). The ptr argument must be a pointer to 
 * an UC_ATOMIC(integer type)
 * For gcc, see http://gcc.gnu.org/onlinedocs/gcc-4.8.1/gcc/_005f_005fsync-Builtins.html
 */
#ifdef DOXYGEN

/** 
 * Define an atomic type.
 * e.g UC_ATOMIC(int) foo;
 */
#define UC_ATOMIC(type)

/**
 * Atomically subtract val from *ptr
 * @return *ptr before the subtraction
 */
#define UC_ATOMIC_SUB(ptr, val) 

/**
 * Atomically add val to *ptr
 * @return *ptr before the addition
 */
#define UC_ATOMIC_ADD(ptr, val)

/**
 * Atomically decrement *ptr
 * @return *ptr before the decrement
 */
#define UC_ATOMIC_DEC(ptr) 

/**
 * Atomically increment *ptr
 * @return *ptr before the increment
 */
#define UC_ATOMIC_INC(ptr) 

/**
 * Atomically get the value of *ptr
 * @return value of *ptr
 */
#define UC_ATOMIC_GET(ptr) 

/**
 * Atomic Compare-And-Swap. If *ptr is oldval, write newwal to *ptr. 
 * @return *ptr that was before the operation.
 */
#define UC_ATOMIC_CAS(ptr, oldval, newval) 

/** Issue a full (hardware) memory barrier.
 * preventing the cpu  to move load/stores across
 * the barrier. (This implies a compiler barrier as well)
 * */
#define UC_MEM_BARRIER() 

/** Issue a full compiler/software only memory barrier 
 * preventing compiler optimization to move load/stores across
 * the barrier.
 * */
#define UC_COMPILER_BARRIER() 

/* clang with atomic extensions */
#elif __clang__

/* clang defines 0 to be memory_order_relaxed and 5 to be memory_order_seq_cst */
#define UC_ORDER_RELAXED 0
#define UC_ORDER_CST 5

#define UC_ATOMIC(type) _Atomic(type)

#define UC_ATOMIC_SUB(ptr, val) __c11_atomic_fetch_sub((ptr), (val), UC_ORDER_CST)

#define UC_ATOMIC_ADD(ptr, val) __c11_atomic_fetch_add((ptr), (val), UC_ORDER_CST)

#define UC_ATOMIC_DEC(ptr) UC_ATOMIC_SUB((ptr), 1)

#define UC_ATOMIC_INC(ptr) UC_ATOMIC_ADD((ptr), 1)

#define UC_ATOMIC_GET(ptr) __c11_atomic_load((ptr), UC_ORDER_CST)

#define UC_ATOMIC_CAS(ptr, oldval, newval) __atomic_compare_exchange((ptr), (oldval), (newval),0, UC_ORDER_CST, UC_ORDER_CST)

#define UC_MEM_BARRIER() __c11_atomic_thread_fence(UC_ORDER_CST)

#define UC_COMPILER_BARRIER() __asm__ __volatile__("": : :"memory")

/* gcc 4.7 or later */
#elif __GNUC_ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 7)

#define UC_ATOMIC(type) type

#define UC_ATOMIC_SUB(ptr, val) __atomic_fetch_sub((ptr), (val), __ATOMIC_SEQ_CST)

#define UC_ATOMIC_ADD(ptr, val) __atomic_fetch_add((ptr), (val), __ATOMIC_SEQ_CST)

#define UC_ATOMIC_DEC(ptr) UC_ATOMIC_SUB((ptr), 1)

#define UC_ATOMIC_INC(ptr) UC_ATOMIC_ADD((ptr), 1)

#define UC_ATOMIC_GET(ptr) __atomic_load_n((ptr), __ATOMIC_SEQ_CST)

#define UC_ATOMIC_CAS(ptr, oldval, newval) __atomic_compare_exchange((ptr), (oldval), (newval),0, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)

#define UC_MEM_BARRIER() __atomic_thread_fence(__ATOMIC_SEQ_CST)

#define UC_COMPILER_BARRIER() __asm__ __volatile__("": : :"memory")


/* Earlier gcc versions */
#elif __GNUC__

#define UC_ATOMIC(type) type

#define UC_ATOMIC_SUB(ptr, val) __sync_fetch_and_sub((ptr), (val))

#define UC_ATOMIC_ADD(ptr, val) __sync_fetch_and_add((ptr), (val))

#define UC_ATOMIC_DEC(ptr) UC_ATOMIC_SUB((ptr), 1)

#define UC_ATOMIC_INC(ptr) UC_ATOMIC_ADD((ptr), 1)

#define UC_ATOMIC_GET(ptr) UC_ATOMIC_ADD((ptr), 0)

#define UC_ATOMIC_CAS(ptr, oldval, newval) __sync_val_compare_and_swap((ptr), (oldval), (newval))

#define UC_MEM_BARRIER() __sync_synchronize()

#define UC_COMPILER_BARRIER() __asm__ __volatile__("": : :"memory")

#else
#error "No atomic operations implemented for this compiler"
#endif


#endif