le_atomic.h

    1 /**
    2  * @page c_atomic Atomic Operation API
    3  *
    4  * @subpage le_atomic.ch "API Reference"
    5  *
    6  * <HR>
    7  *
    8  * An atomic operation interface for Legato.  Using an atomic operation has two effects:
    9  *  - Ensures all threads either see the whole operation performed, or none of it, and
   10  *  - Provides guarantees on when the effects of an operation are seen by other threads,
   11  *    relative to the surrounding code.
   12  */
   13 
   14 #ifndef LEGATO_ATOMIC_INCLUDE_GUARD
   15 #define LEGATO_ATOMIC_INCLUDE_GUARD
   16 
   17 #ifdef __GNUC__
   18 
   19 /**
   20  * Does not create ordering constraints between threads.
   21  */
   22 #define LE_ATOMIC_ORDER_RELAXED __ATOMIC_RELAXED
   23 
   24 /**
   25  * Creates a constraint that guarantees this operation will occur before all later operations,
   26  * as seen by all threads.
   27  */
   28 #define LE_ATOMIC_ORDER_ACQUIRE __ATOMIC_ACQUIRE
   29 
   30 /**
   31  * Creates a constraint that guarantees this operation will occur after all previous operations,
   32  * as seen by all threads.
   33  */
   34 #define LE_ATOMIC_ORDER_RELEASE __ATOMIC_RELEASE
   35 
   36 /**
   37  * Combines the effects of LE_ATOMIC_ORDER_ACQUIRE and LE_ATOMIC_ORDER_RELEASE
   38  */
   39 #define LE_ATOMIC_ORDER_ACQ_REL __ATOMIC_ACQ_REL
   40 
   41 /**
   42  * Test if a value has previously been set, and set it to true.  This returns true if and only if
   43  * the value was previously true.
   44  *
   45  * @param ptr points to a bool.
   46  * @param order ordering constraint
   47  */
   48 #define LE_ATOMIC_TEST_AND_SET(ptr, order) __atomic_test_and_set((ptr), (order))
   49 
   50 /**
   51  * Performs an atomic add operation. Results are stored in address pointed to by ptr
   52  *
   53  * @return output value of operation
   54  */
   55 #define LE_ATOMIC_ADD_FETCH(ptr, value, order)  __sync_add_and_fetch((ptr), (value))
   56 
   57 /**
   58  * Performs an atomic subtract operation. Results are stored in address pointed to by ptr
   59  *
   60  * @return output value of operation
   61  */
   62 #define LE_ATOMIC_SUB_FETCH(ptr, value, order)  __sync_sub_and_fetch((ptr), (value))
   63 
   64 /**
   65  * Performs an atomic bitwise-OR operation. Results are stored in address pointed to by ptr
   66  *
   67  * @return output value of operation
   68  */
   69 #define LE_ATOMIC_OR_FETCH(ptr, value, order)  __sync_or_and_fetch((ptr), (value))
   70 
   71 /**
   72  * Performs an atomic bitwise-AND operation. Results are stored in address pointed to by ptr
   73  *
   74  * @return output value of operation
   75  */
   76 #define LE_ATOMIC_AND_FETCH(ptr, value, order) __sync_and_and_fetch((ptr), (value))
   77 
   78 /**
   79  * Perform an atomic compare and swap. If the current value of *ptr is oldval, then write newval
   80  * into *ptr.
   81  *
   82  * @return True if comparison is successful and newval was written
   83  */
   84 #define LE_SYNC_BOOL_COMPARE_AND_SWAP(ptr, oldval, newval) \
   85             __sync_bool_compare_and_swap((ptr), (oldval), (newval))
   86 
   87 #else /* !__GCC__ */
   88 
   89 // On compilers other than GCC, the framework adaptor must provide an implementation.
   90 #ifndef LE_ATOMIC_ORDER_RELAXED
   91 #error "The frameworkAdaptor is missing a definition of LE_ATOMIC_ORDER_RELAXED"
   92 #endif
   93 
   94 #ifndef LE_ATOMIC_ORDER_ACQUIRE
   95 #error "The frameworkAdaptor is missing a definition of LE_ATOMIC_ORDER_ACQUIRE"
   96 #endif
   97 
   98 #ifndef LE_ATOMIC_ORDER_RELEASE
   99 #error "The frameworkAdaptor is missing a definition of LE_ATOMIC_ORDER_RELEASE"
  100 #endif
  101 
  102 #ifndef LE_ATOMIC_ORDER_ACQ_REL
  103 #error "The frameworkAdaptor is missing a definition of LE_ATOMIC_ORDER_ACQ_REL"
  104 #endif
  105 
  106 #ifndef LE_ATOMIC_TEST_AND_SET
  107 #error "The frameworkAdaptor is missing a definition of LE_ATOMIC_TEST_AND_SET"
  108 #endif
  109 
  110 #ifndef LE_ATOMIC_ADD_FETCH
  111 #error "The frameworkAdaptor is missing a definition of LE_ATOMIC_ADD_FETCH"
  112 #endif
  113 
  114 #ifndef LE_ATOMIC_SUB_FETCH
  115 #error "The frameworkAdaptor is missing a definition of LE_ATOMIC_SUB_FETCH"
  116 #endif
  117 
  118 #ifndef LE_ATOMIC_OR_FETCH
  119 #error "The frameworkAdaptor is missing a definition of LE_ATOMIC_OR_FETCH"
  120 #endif
  121 
  122 #ifndef LE_ATOMIC_AND_FETCH
  123 #error "The frameworkAdaptor is missing a definition of LE_ATOMIC_AND_FETCH"
  124 #endif
  125 
  126 #ifndef LE_SYNC_BOOL_COMPARE_AND_SWAP
  127 #error "The frameworkAdaptor is missing a definition of LE_SYNC_BOOL_COMPARE_AND_SWAP"
  128 #endif
  129 
  130 #endif /* __GCC__ */
  131 
  132 #endif // LEGATO_ATOMIC_INCLUDE_GUARD