mirror of https://github.com/python/cpython
95 lines
2.4 KiB
C
95 lines
2.4 KiB
C
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/* Atomic functions: similar to pycore_atomic.h, but don't need
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to declare variables as atomic.
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Py_ssize_t type:
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* value = _Py_atomic_size_get(&var)
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* _Py_atomic_size_set(&var, value)
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Use sequentially-consistent ordering (__ATOMIC_SEQ_CST memory order):
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enforce total ordering with all other atomic functions.
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*/
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#ifndef Py_ATOMIC_FUNC_H
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#define Py_ATOMIC_FUNC_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef Py_BUILD_CORE
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# error "this header requires Py_BUILD_CORE define"
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#endif
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#if defined(_MSC_VER)
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# include <intrin.h> // _InterlockedExchange()
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#endif
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// Use builtin atomic operations in GCC >= 4.7 and clang
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#ifdef HAVE_BUILTIN_ATOMIC
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static inline Py_ssize_t _Py_atomic_size_get(Py_ssize_t *var)
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{
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return __atomic_load_n(var, __ATOMIC_SEQ_CST);
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}
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static inline void _Py_atomic_size_set(Py_ssize_t *var, Py_ssize_t value)
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{
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__atomic_store_n(var, value, __ATOMIC_SEQ_CST);
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}
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#elif defined(_MSC_VER)
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static inline Py_ssize_t _Py_atomic_size_get(Py_ssize_t *var)
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{
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#if SIZEOF_VOID_P == 8
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Py_BUILD_ASSERT(sizeof(__int64) == sizeof(*var));
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volatile __int64 *volatile_var = (volatile __int64 *)var;
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__int64 old;
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do {
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old = *volatile_var;
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} while(_InterlockedCompareExchange64(volatile_var, old, old) != old);
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#else
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Py_BUILD_ASSERT(sizeof(long) == sizeof(*var));
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volatile long *volatile_var = (volatile long *)var;
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long old;
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do {
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old = *volatile_var;
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} while(_InterlockedCompareExchange(volatile_var, old, old) != old);
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#endif
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return old;
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}
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static inline void _Py_atomic_size_set(Py_ssize_t *var, Py_ssize_t value)
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{
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#if SIZEOF_VOID_P == 8
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Py_BUILD_ASSERT(sizeof(__int64) == sizeof(*var));
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volatile __int64 *volatile_var = (volatile __int64 *)var;
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_InterlockedExchange64(volatile_var, value);
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#else
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Py_BUILD_ASSERT(sizeof(long) == sizeof(*var));
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volatile long *volatile_var = (volatile long *)var;
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_InterlockedExchange(volatile_var, value);
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#endif
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}
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#else
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// Fallback implementation using volatile
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static inline Py_ssize_t _Py_atomic_size_get(Py_ssize_t *var)
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{
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volatile Py_ssize_t *volatile_var = (volatile Py_ssize_t *)var;
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return *volatile_var;
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}
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static inline void _Py_atomic_size_set(Py_ssize_t *var, Py_ssize_t value)
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{
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volatile Py_ssize_t *volatile_var = (volatile Py_ssize_t *)var;
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*volatile_var = value;
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}
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#endif
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#ifdef __cplusplus
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}
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#endif
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#endif /* Py_ATOMIC_FUNC_H */
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