OvmfPkg/XenBusDxe/InterlockedCompareExchange16.c

   1 #include <Library/DebugLib.h>
   2 #include "InterlockedCompareExchange16.h"
   3
   4 /**
   5   Performs an atomic compare exchange operation on a 16-bit unsigned integer.
   6
   7   Performs an atomic compare exchange operation on the 16-bit unsigned integer
   8   specified by Value.  If Value is equal to CompareValue, then Value is set to
   9   ExchangeValue and CompareValue is returned.  If Value is not equal to CompareValue,
  10   then Value is returned.  The compare exchange operation must be performed using
  11   MP safe mechanisms.
  12
  13   If Value is NULL, then ASSERT().
  14
  15   @param  Value         A pointer to the 16-bit value for the compare exchange
  16                         operation.
  17   @param  CompareValue  16-bit value used in compare operation.
  18   @param  ExchangeValue 16-bit value used in exchange operation.
  19
  20   @return The original *Value before exchange.
  21
  22 **/
  23 UINT16
  24 EFIAPI
  25 InterlockedCompareExchange16 (
  26   IN OUT  UINT16                    *Value,
  27   IN      UINT16                    CompareValue,
  28   IN      UINT16                    ExchangeValue
  29   )
  30 {
  31   ASSERT (Value != NULL);
  32   return InternalSyncCompareExchange16 (Value, CompareValue, ExchangeValue);
  33 }