/* Performs an atomic compare exchange operation on the 16-bit unsigned integer specified by Value. If Value is equal to CompareValue, then Value is set to ExchangeValue and CompareValue is returned. If Value is not equal to CompareValue, then Value is returned. The compare exchange operation must be performed using MP safe mechanisms. */
UINT16 EFIAPI InternalSyncCompareExchange16(IN volatile UINT16 *Value, IN UINT16 CompareValue, IN UINT16 ExchangeValue)
/* Performs an atomic compare exchange operation on the 16-bit unsigned integer specified by Value. If Value is equal to CompareValue, then Value is set to ExchangeValue and CompareValue is returned. If Value is not equal to CompareValue, then Value is returned. The compare exchange operation must be performed using MP safe mechanisms. */
UINT16 EFIAPI InternalSyncCompareExchange16(IN volatile UINT16 *Value, IN UINT16 CompareValue, IN UINT16 ExchangeValue)
{
  _asm {
    mov     ecx, Value
    mov     ax, CompareValue
    mov     dx, ExchangeValue
    lock    cmpxchg [ecx], dx
  }
}