Re: Rep Specing Variant Records

[Petter <petter_fryklund@hotmail.com>]

Yes, discriminants do take up size.

This is how I would do it:

type Stuff (Has_Extra : Boolean) is record
     Foo : Integer;
     Bar : Integer;
     case Has_Extra is
         when True =>
             Blah : Float;
         when False =>
             null;
     end case;
 end record;

 for Stuff use record
     Has_Extra at  0 range 0 .. 31;
     Foo       at  4 range 0 .. 31;
     Bar       at  8 range 0 .. 31;
     Blah      at 12 range 0 .. 31;
 end record;

type Other_Stuff (Has_Blah : Boolean) is record
     Foo : Integer;
     Bar : Integer;
     case Has_Blah is
         when True =>
             Blah : Float;
         when False =>
             Blip : Integer;
     end case;
 end record;

 for Other_Stuff use record
     Has_Blah  at  0 range 0 .. 31;
     Foo       at  4 range 0 .. 31;
     Bar       at  8 range 0 .. 31;
     Blah      at 12 range 0 .. 31;
     Blip      at 12 range 0 .. 31;
 end record;