Forum Post: RE: I/O Interface API

thank you for reply...

I'm using Microsoft Visual Studio (both C++ / C#) for app development in WinCE 6.0.

#ifndef CTL_CODE

#define CTL_CODE( DeviceType, Function, Method, Access ) ( \
((DeviceType) << 16) | ((Access) << 14) | ((Function) << 2) | (Method) \
)
#endif

#define IOCTL_GPIO_SETBIT  \
CTL_CODE(FILE_DEVICE_UNKNOWN, 0x0300, METHOD_BUFFERED, FILE_ANY_ACCESS)

Now, my questions is:

• What's the meaning of function "0x0300" in above code?  
• It's SET the GPIO:bit TRUE, But how?
• Is it same in any kit, even my custom board?

Best regards...