The __stdcall calling convention is used by default when calling DLL functions. This calling convention is used by all Windows API DLL functions.
You can change the calling convention for a DLL function by using the CallingConvention property of the DllFunctionOptions attribute.
<Dll("msvcrt.dll")> Public Interface IMsVisualCRuntime <DllFunctionOptions(CallingConvention:=CallingConvention.Cdecl)> Function cos(ByVal input As Double) As Double End Interface