[Lazarus] Need help with LibIconv

[ListMember]

I need to convert one char (codepoint) in one encoding to another char 
(codepoint) in a different encoding.

And, I need to do that one char (codepoint) at a time (IOW, no strings; 
just a single char/codepoint).

This is the function prototype I'd like to use in my application:

function ConvertCodePoint(
     InCP: Integer; {incoming codepoint}
     InEncoding: Integer; { incoming codepoint's encoding}
     OutEncoding: Integer; { resulting codepoint's encoding}
     out OutCP: Integer; { resulting codepoint }
     out ErrorCode: Integer {error code}
   );
begin
   {LibIconv fils the void here.}
end;

But, I have absolutely no idea how to fill the void between 'begin' and 
'end'.

One more thing: Even though the iconv docs say it supports many 
encodings, I couldn't find any information on what the named constants 
are (to use for 'InEncoding' and 'OutEncoding' in the above function).

Where can I find them?

Could someone help please.