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| <!--*********************************************************************--> |
| <h1><atomic> design</h1> |
| <!--*********************************************************************--> |
| |
| <p> |
| This is more of a synopsis than a true description. The compiler supplies all |
| of the intrinsics as described below. This list of intrinsics roughly parallels |
| the requirements of the C and C++ atomics proposals. The C and C++ library |
| imlpementations simply drop through to these intrinsics. Anything the platform |
| does not support in hardware, the compiler arranges for a (compiler-rt) library |
| call to be made which will do the job with a mutex, and in this case ignoring |
| the memory ordering parameter. |
| </p> |
| |
| <blockquote><pre> |
| <font color="#C80000">// In every intrinsic signature below, type* atomic_obj may be a pointer to a</font> |
| <font color="#C80000">// volatile-qualifed type.</font> |
| |
| <font color="#C80000">// type must be trivially copyable</font> |
| bool __atomic_is_lock_free(const type* atomic_obj); |
| |
| <font color="#C80000">// type must be trivially copyable</font> |
| <font color="#C80000">// Behavior is defined for mem_ord = 0, 1, 2, 5</font> |
| type __atomic_load(const type* atomic_obj, int mem_ord); |
| |
| <font color="#C80000">// type must be trivially copyable</font> |
| <font color="#C80000">// Behavior is defined for mem_ord = 0, 3, 5</font> |
| type __atomic_store(type* atomic_obj, type desired, int mem_ord); |
| |
| <font color="#C80000">// type must be trivially copyable</font> |
| <font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font> |
| type __atomic_exchange(type* atomic_obj, type desired, int mem_ord); |
| |
| <font color="#C80000">// type must be trivially copyable</font> |
| <font color="#C80000">// Behavior is defined for mem_success = [0 ... 5],</font> |
| <font color="#C80000">// mem_falure <= mem_success</font> |
| bool __atomic_compare_exchange_strong(type* atomic_obj, |
| type* expected, type desired, |
| int mem_success, int mem_failure); |
| |
| <font color="#C80000">// type must be trivially copyable</font> |
| <font color="#C80000">// Behavior is defined for mem_success = [0 ... 5],</font> |
| <font color="#C80000">// mem_falure <= mem_success</font> |
| bool __atomic_compare_exchange_weak(type* atomic_obj, |
| type* expected, type desired, |
| int mem_success, int mem_failure); |
| |
| <font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font> |
| <font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font> |
| <font color="#C80000">// char16_t, char32_t, wchar_t</font> |
| <font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font> |
| type __atomic_fetch_add(type* atomic_obj, type operand, int mem_ord); |
| |
| <font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font> |
| <font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font> |
| <font color="#C80000">// char16_t, char32_t, wchar_t</font> |
| <font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font> |
| type __atomic_fetch_sub(type* atomic_obj, type operand, int mem_ord); |
| |
| <font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font> |
| <font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font> |
| <font color="#C80000">// char16_t, char32_t, wchar_t</font> |
| <font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font> |
| type __atomic_fetch_and(type* atomic_obj, type operand, int mem_ord); |
| |
| <font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font> |
| <font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font> |
| <font color="#C80000">// char16_t, char32_t, wchar_t</font> |
| <font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font> |
| type __atomic_fetch_or(type* atomic_obj, type operand, int mem_ord); |
| |
| <font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font> |
| <font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font> |
| <font color="#C80000">// char16_t, char32_t, wchar_t</font> |
| <font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font> |
| type __atomic_fetch_xor(type* atomic_obj, type operand, int mem_ord); |
| |
| <font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font> |
| void* __atomic_fetch_add(void** atomic_obj, ptrdiff_t operand, int mem_ord); |
| void* __atomic_fetch_sub(void** atomic_obj, ptrdiff_t operand, int mem_ord); |
| |
| <font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font> |
| void __atomic_thread_fence(int mem_ord); |
| void __atomic_signal_fence(int mem_ord); |
| </pre></blockquote> |
| |
| <p> |
| If desired the intrinsics taking a single <tt>mem_ord</tt> parameter can default |
| this argument to 5. |
| </p> |
| |
| <p> |
| If desired the intrinsics taking two ordering parameters can default |
| <tt>mem_success</tt> to 5, and <tt>mem_failure</tt> to <tt>mem_success</tt>. |
| </p> |
| |
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