[fpc-pascal] How to find address of record member

[Martin]

On 08/07/2018 17:07, Bo Berglund wrote:
> Say I have a record type defined like this:
>
>    TAppData = packed record  //Total 8 bytes per app
>      ActiveToken: word; //Matches constant for app if active
>      Option: word;      //16 option bits
>      ExpDate: word;     //Integer TDateTime values
>      Info: word;        //16 info bits
>    end;
>
> The data is stored in a security dongle memory which can be accessed
> only a word at a time by its word address 0..55.
>
> I want to write my code such that the address to the individual member
> is calculated automatically so if the record type is modified it will
> still work.
>

var AppData: TAppData absolute 0;
begin
writeln( ptrint( @AppData.Option ));

You can also take a variable without "absolute"
@AppData.Option - @AppData