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<title><atomic> design</title>
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<h1><atomic> design</h1>
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<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>.
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