Re: Interfacing Ada to C

[Samuel Tardieu <sam@ada.eu.org>]

>>>>> "Rune" == Rune Wemberg <ruw@ffi.no> writes:

Rune> Does anyone know what a packed Ada record is?

It's a record on which you apply a pragma Pack. For example, the
following type R is a packed record:

  type My_Natural is range 0 .. 15;
  for My_Natural'Size use 4;

  type R is record
    A, B : My_Natural;
  end record;
  pragma Pack (R);
  for R'Size use 8;

If you do:

  My_R : aliased constant R := (1, 2);

then My_R will be represented in memory by a single byte containing
00010010 (or 00100001, depending on the endianness).

Here is the code generated by GNAT for the m68k:

.data
_t__my_r:
        .byte 0x12

Hope this helps.

  Sam
-- 
Samuel Tardieu -- sam@ada.eu.org