C11 atomic operations

Collaboration diagram for C11 atomic operations:

Modules
	Stub replacements of C11 atomic operations
	Atomic_macros
	Atomic_enum
	Atomic_types
	Memory Fences
Defines
#define	atomic_compare_exchange_weak(OBJP, EXPECTED, DESIRED)
	Atomically compare *OBJP to *EXPECTED and set it to DESIRED if they are equal.
#define	atomic_exchange(OBJP, DESIRED)
	Store DESIRED into the object behind OBJP and return its previous value.
#define	atomic_fetch_add(OBJP, OPERAND)   P00_FETCH_OP((OBJP), (OPERAND), __sync_fetch_and_add, +=)
	Atomically add OPERAND to *OBJP.
#define	atomic_fetch_add_conditional(OBJP, OPERAND)
#define	atomic_fetch_and(OBJP, OPERAND)   P00_FETCH_OP((OBJP), (OPERAND), __sync_fetch_and_and, &=)
	Atomically do a bitwise AND operation between OPERAND and *OBJP.
#define	atomic_fetch_max(OBJP, OPERAND)
#define	atomic_fetch_or(OBJP, OPERAND)   P00_FETCH_OP((OBJP), (OPERAND), __sync_fetch_and_or, |=)
	Atomically do a bitwise OR operation between OPERAND and *OBJP.
#define	atomic_fetch_sub(OBJP, OPERAND)   P00_FETCH_OP((OBJP), (OPERAND), __sync_fetch_and_sub, -=)
	Atomically subtract OPERAND from *OBJP.
#define	atomic_fetch_xor(OBJP, OPERAND)   P00_FETCH_OP((OBJP), (OPERAND), __sync_fetch_and_xor, ^=)
	Atomically do a bitwise XOR operation between OPERAND and *OBJP.
#define	atomic_init(OBJP, VAL)
	Initialize the object behind OBJP with value VAL.
#define	atomic_is_lock_free(OBJP)   (!offsetof(__typeof__(*OBJP), p00_xval))
	return true if OBJP points to a lock-free object
#define	atomic_load(OBJP)
	Return the value of the object behind OBJP.
#define	atomic_store(OBJP, DES)
	Store DESIRED into the object behind OBJP.
#define	P99_CRITICAL
	Protect the following block or statement as a critical section of the program.
#define	P99_FIFO(T)   P99_PASTE2(p00_fifo_, T)
#define	P99_FIFO_APPEND(L, EL)
	Append element EL to an atomic FIFO L.
#define	P99_FIFO_CLEAR(L)
	Atomically clear an atomic FIFO L and return a pointer to the start of the list that it previously contained.
#define	P99_FIFO_DECLARE(T)
#define	P99_FIFO_INITIALIZER(HEAD, TAIL)
#define	P99_FIFO_POP(L)
	Pop the front element from an atomic FIFO L.
#define	P99_FIFO_TABULATE(TYPE, TAB, L)
#define	P99_LIFO(T)   _Atomic(P99_PASTE2(p00_lifo_, T))
#define	P99_LIFO_CLEAR(L)   atomic_exchange(L, 0)
	Atomically clear an atomic LIFO L and return a pointer to the start of the list that it previously contained.
#define	P99_LIFO_DECLARE(T)
#define	P99_LIFO_INITIALIZER(VAL)   ATOMIC_VAR_INIT((void*)VAL)
#define	P99_LIFO_POP(L)
	Pop the top element from an atomic LIFO L.
#define	P99_LIFO_PUSH(L, EL)
	Push element EL into an atomic LIFO L.
#define	P99_LIFO_TABULATE(TYPE, TAB, L)
#define	P99_LIFO_TOP(L)   atomic_load(L)
	Return a pointer to the top element of an atomic LIFO L.
#define	P99_SPIN_EXCLUDE(FLAGP)
	Protect the following block or statement as a critical section of the program by using FLAGP as a spinlock.
Functions
void	atomic_flag_clear (volatile atomic_flag *p00_objp)
	Unconditionally set *p00_objp to false.
void	atomic_flag_clear_explicit (volatile atomic_flag *p00_objp, memory_order p00_ord)
	Unconditionally set *p00_objp to false.
void	atomic_flag_lock (volatile atomic_flag *p00_objp)
	extension: spin on p00_objp setting the flag until the state before was "clear"
_Bool	atomic_flag_test_and_set (volatile atomic_flag *p00_objp)
	Unconditionally set *object to true and return the previous value.
_Bool	atomic_flag_test_and_set_explicit (volatile atomic_flag *p00_objp, memory_order p00_ord)
	Unconditionally set *object to true and return the previous value.
_Bool	atomic_flag_trylock (volatile atomic_flag *p00_objp)
	extension: set the flag and return true if we are the first to do so
void	atomic_flag_unlock (volatile atomic_flag *p00_objp)
	extension: clear the flag unconditionally

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Detailed Description

This is a stub implementation of C11 atomic types and operations.

This uses gcc extensions

• all those that are needed for P99_GENERIC
• __typeof__ to declare typedef or local variables of a specific type
• block expressions with ({ ... })

We also use __sync_lock_test_and_set and other similar built-ins if they are available. If not, __sync_lock_test_and_set and __sync_lock_release are implemented in assembler (for 4 byte integers) and all other operations are synthesized with an atomic_flag that is used as a spinlock.

See also:

_Atomic

P99_DECLARE_ATOMIC