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34 <!--*********************************************************************-->
35 <h1>&lt;atomic&gt; design</h1>
36 <!--*********************************************************************-->
37
38<p>
39This is more of a synopsis than a true description. The compiler supplies all
40of the intrinsics as described below. This list of intrinsics roughly parallels
41the requirements of the C and C++ atomics proposals. The C and C++ library
42imlpementations simply drop through to these intrinsics. Anything the platform
43does not support in hardware, the compiler arranges for a (compiler-rt) library
44call to be made which will do the job with a mutex, and in this case ignoring
45the memory ordering parameter.
46</p>
47
48<blockquote><pre>
49<font color="#C80000">// type can be any pod</font>
50<font color="#C80000">// Behavior is defined for mem_ord = 0, 1, 2, 5</font>
51type __atomic_load(const volatile type* atomic_obj, int mem_ord);
52
53<font color="#C80000">// type can be any pod</font>
54<font color="#C80000">// Behavior is defined for mem_ord = 0, 3, 5</font>
55type __atomic_store(volatile type* atomic_obj, type desired, int mem_ord);
56
57<font color="#C80000">// type can be any pod</font>
58<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
59type __atomic_exchange(volatile type* atomic_obj, type desired, int mem_ord);
60
61<font color="#C80000">// type can be any pod</font>
62<font color="#C80000">// Behavior is defined for mem_success = [0 ... 5],</font>
63<font color="#C80000">// mem_falure &lt;= mem_success &amp;&amp; mem_failure != [3, 4]</font>
64bool __atomic_compare_exchange_strong(volatile type* atomic_obj,
65 type* expected, type desired,
66 int mem_success, int mem_failure);
67
68<font color="#C80000">// type can be any pod</font>
69<font color="#C80000">// Behavior is defined for mem_success = [0 ... 5],</font>
70<font color="#C80000">// mem_falure &lt;= mem_success &amp;&amp; mem_failure != [3, 4]</font>
71bool __atomic_compare_exchange_weak(volatile type* atomic_obj,
72 type* expected, type desired,
73 int mem_success, int mem_failure);
74
75<font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font>
76<font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font>
77<font color="#C80000">// char16_t, char32_t, wchar_t</font>
78<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
79type __atomic_fetch_add(volatile type* atomic_obj, type operand, int mem_ord);
80
81<font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font>
82<font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font>
83<font color="#C80000">// char16_t, char32_t, wchar_t</font>
84<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
85type __atomic_fetch_sub(volatile type* atomic_obj, type operand, int mem_ord);
86
87<font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font>
88<font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font>
89<font color="#C80000">// char16_t, char32_t, wchar_t</font>
90<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
91type __atomic_fetch_and(volatile type* atomic_obj, type operand, int mem_ord);
92
93<font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font>
94<font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font>
95<font color="#C80000">// char16_t, char32_t, wchar_t</font>
96<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
97type __atomic_fetch_or(volatile type* atomic_obj, type operand, int mem_ord);
98
99<font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font>
100<font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font>
101<font color="#C80000">// char16_t, char32_t, wchar_t</font>
102<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
103type __atomic_fetch_xor(volatile type* atomic_obj, type operand, int mem_ord);
104
105<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
106void* __atomic_fetch_add(void* volatile* atomic_obj, ptrdiff_t operand, int mem_ord);
107void* __atomic_fetch_sub(void* volatile* atomic_obj, ptrdiff_t operand, int mem_ord);
108
109<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
110void __atomic_thread_fence(int mem_ord);
111void __atomic_signal_fence(int mem_ord);
112</pre></blockquote>
113
114<p>
115If desired the intrinsics taking a single <tt>mem_ord</tt> parameter can default
116this argument to 5.
117</p>
118
119<p>
120If desired the intrinsics taking two ordering parameters can default
121<tt>mem_success</tt> to 5, and <tt>mem_failure</tt> to <tt>mem_success</tt>.
122</p>
123
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