/*
- * Copyright (c) 2013 Nicira, Inc.
+ * Copyright (c) 2013, 2014 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
*
* This library implements atomic operations with an API based on the one
* defined in C11. It includes multiple implementations for compilers and
- * libraries with varying degrees of built-in support for C11, including an
+ * libraries with varying degrees of built-in support for C11, including a
* fallback implementation for systems that have pthreads but no other support
* for atomics.
*
*
* (*) Not specified by C11.
*
+ * Atomic types may also be obtained via ATOMIC(TYPE), e.g. ATOMIC(void *).
+ * Only basic integer types and pointer types can be made atomic this way,
+ * e.g. atomic structs are not supported.
+ *
* The atomic version of a type doesn't necessarily have the same size or
* representation as the ordinary version; for example, atomic_int might be a
- * typedef for a struct that also includes a mutex. The range of an atomic
- * type does match the range of the corresponding ordinary type.
+ * typedef for a struct. The range of an atomic type does match the range of
+ * the corresponding ordinary type.
*
* C11 says that one may use the _Atomic keyword in place of the typedef name,
* e.g. "_Atomic int" instead of "atomic_int". This library doesn't support
* that.
*
*
- * Initialization
- * ==============
+ * Life Cycle
+ * ==========
*
* To initialize an atomic variable at its point of definition, use
* ATOMIC_VAR_INIT:
* atomic_flag is a typedef for a type with two states, set and clear, that
* provides atomic test-and-set functionality.
*
+ *
+ * Life Cycle
+ * ----------
+ *
* ATOMIC_FLAG_INIT is an initializer for atomic_flag. The initial state is
* "clear".
*
+ * An atomic_flag may also be initialized at runtime with atomic_flag_clear().
+ *
+ *
+ * Operations
+ * ----------
+ *
* The following functions are available.
*
* bool atomic_flag_test_and_set(atomic_flag *object)
#include "ovs-atomic-pthreads.h"
#elif HAVE_STDATOMIC_H
#include "ovs-atomic-c11.h"
+ #elif __has_extension(c_atomic)
+ #include "ovs-atomic-clang.h"
#elif __GNUC__ >= 4 && __GNUC_MINOR__ >= 7
#include "ovs-atomic-gcc4.7+.h"
#elif HAVE_GCC4_ATOMICS
#endif
#undef IN_OVS_ATOMIC_H
+#ifndef OMIT_STANDARD_ATOMIC_TYPES
+typedef ATOMIC(bool) atomic_bool;
+
+typedef ATOMIC(char) atomic_char;
+typedef ATOMIC(signed char) atomic_schar;
+typedef ATOMIC(unsigned char) atomic_uchar;
+
+typedef ATOMIC(short) atomic_short;
+typedef ATOMIC(unsigned short) atomic_ushort;
+
+typedef ATOMIC(int) atomic_int;
+typedef ATOMIC(unsigned int) atomic_uint;
+
+typedef ATOMIC(long) atomic_long;
+typedef ATOMIC(unsigned long) atomic_ulong;
+
+typedef ATOMIC(long long) atomic_llong;
+typedef ATOMIC(unsigned long long) atomic_ullong;
+
+typedef ATOMIC(size_t) atomic_size_t;
+typedef ATOMIC(ptrdiff_t) atomic_ptrdiff_t;
+
+typedef ATOMIC(intmax_t) atomic_intmax_t;
+typedef ATOMIC(uintmax_t) atomic_uintmax_t;
+
+typedef ATOMIC(intptr_t) atomic_intptr_t;
+typedef ATOMIC(uintptr_t) atomic_uintptr_t;
+#endif /* !OMIT_STANDARD_ATOMIC_TYPES */
+
+/* Nonstandard atomic types. */
+typedef ATOMIC(uint8_t) atomic_uint8_t;
+typedef ATOMIC(uint16_t) atomic_uint16_t;
+typedef ATOMIC(uint32_t) atomic_uint32_t;
+typedef ATOMIC(uint64_t) atomic_uint64_t;
+
+typedef ATOMIC(int8_t) atomic_int8_t;
+typedef ATOMIC(int16_t) atomic_int16_t;
+typedef ATOMIC(int32_t) atomic_int32_t;
+typedef ATOMIC(int64_t) atomic_int64_t;
+
+/* Reference count. */
+struct ovs_refcount {
+ atomic_uint count;
+};
+
+/* Initializes 'refcount'. The reference count is initially 1. */
+static inline void
+ovs_refcount_init(struct ovs_refcount *refcount)
+{
+ atomic_init(&refcount->count, 1);
+}
+
+/* Increments 'refcount'. */
+static inline void
+ovs_refcount_ref(struct ovs_refcount *refcount)
+{
+ unsigned int old_refcount;
+
+ atomic_add(&refcount->count, 1, &old_refcount);
+ ovs_assert(old_refcount > 0);
+}
+
+/* Decrements 'refcount' and returns the previous reference count. Often used
+ * in this form:
+ *
+ * if (ovs_refcount_unref(&object->ref_cnt) == 1) {
+ * // ...uninitialize object...
+ * free(object);
+ * }
+ */
+static inline unsigned int
+ovs_refcount_unref(struct ovs_refcount *refcount)
+{
+ unsigned int old_refcount;
+
+ atomic_sub(&refcount->count, 1, &old_refcount);
+ ovs_assert(old_refcount > 0);
+ return old_refcount;
+}
+
+/* Reads and returns 'ref_count_''s current reference count.
+ *
+ * Rarely useful. */
+static inline unsigned int
+ovs_refcount_read(const struct ovs_refcount *refcount_)
+{
+ struct ovs_refcount *refcount
+ = CONST_CAST(struct ovs_refcount *, refcount_);
+ unsigned int count;
+
+ atomic_read(&refcount->count, &count);
+ return count;
+}
+
#endif /* ovs-atomic.h */
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