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    InterlockedCompareExchange

    Conditional exchange.

    Declaration

    Source position: systemh.inc line 1643

    function InterlockedCompareExchange(var Target: LongInt; 
                                   NewValue: LongInt; 
                                   Comperand: LongInt) : LongInt;

    function InterlockedCompareExchange(var Target: Pointer; 
                                   NewValue: Pointer; 
                                   Comperand: Pointer) : Pointer;external name 'FPC_INTERLOCKEDCOMPAREEXCHANGE64';

    function InterlockedCompareExchange(var Target: Cardinal; 
                                   NewValue: Cardinal; 
                                   Comperand: Cardinal) : Cardinal;external name 'FPC_INTERLOCKEDCOMPAREEXCHANGE';

    Description

    InterlockedCompareExchange does an compare-and-exchange operation on the specified values in a thread-safe way. The function compares Target and Comperand and exchanges Target with NewValue if Target and Comperand are equal. It returns the old value of Target. This is done in a thread-safe way, i.e., only one processor is accessing the Target variable at a time.

    Errors

    None.

    See also

    Name Description
    InterLockedDecrement Thread-safe decrement.
    InterLockedIncrement Thread-safe increment.
    InterLockedExchange Exchange 2 integers in a thread-safe way.
    InterLockedExchangeAdd Thread-safe add and exchange of 2 values.