This call allows a process to query the code page currently used to display text data.
VioGetCp
Reserved (USHORT) - input
The display code page ID previously set by VioSetCp, or inherited from the requesting process, is returned to the caller.
The code page tag returned is the currently active code page. A value of 0000 indicates that the code page in use is the ROM code page provided by the hardware.
If ERROR_VIO_USER_FONT is returned, it indicates a user font that was previously loaded with VioSetFont is the active code page.