Synchronization Primitives

The synchronization primitive intrinsics provide a variety of operations. Besides performing these operations, each intrinsic has two key properties:

• the function performed is guaranteed to be atomic
• associated with each intrinsic are certain memory barrier properties that restrict the movement of memory references to visible data across the intrinsic operation by either the compiler or the processor

For the intrinsics listed below, <type> is either a 32-bit or 64-bit integer.

Atomic Fetch-and-op Operations

<type> __sync_fetch_and_add(<type> *ptr,<type> val)
<type> __sync_fetch_and_and(<type> *ptr,<type> val)
<type> __sync_fetch_and_nand(<type> *ptr,<type> val)
<type> __sync_fetch_and_or(<type> *ptr,<type> val)
<type> __sync_fetch_and_sub(<type> *ptr,<type> val)
<type> __sync_fetch_and_xor(<type> *ptr,<type> val)

Atomic Op-and-fetch Operations

<type> __sync_add_and_fetch(<type> *ptr,<type> val)
<type> __sync_sub_and_fetch(<type> *ptr,<type> val)
<type> __sync_or_and_fetch(<type> *ptr,<type> val)
<type> __sync_and_and_fetch(<type> *ptr,<type> val)
<type> __sync_nand_and_fetch(<type> *ptr,<type> val)
<type> __sync_xor_and_fetch(<type> *ptr,<type> val)

Atomic Compare-and-swap Operations

<type> __sync_val_compare_and_swap(<type> *ptr, <type> old_val, <type> new_val)
int __sync_bool_compare_and_swap(<type> *ptr, <type> old_val, <type> new_val)

Atomic Synchronize Operation

void __sync_synchronize (void);

Atomic Lock-test-and-set Operation

<type> __sync_lock_test_and_set(<type> *ptr,<type> val)

Atomic Lock-release Operation

void __sync_lock_release(<type> *ptr)