Re: creating a 16 bit value from 2 8 bit values in Ada

[Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov>]

ma740988@pegasus.cc.ucf.edu (Mark) writes:

> Could someone show me how to concatenate the Hi and Lo components? 
> The end result - obviously - would be a 16 bit value.  I've waded
> through my ada books here and keep coming up short?

Others have pointed out ' lo + 256 * hi'. Another choice is:

type Double_Byte_Type is record
    Lo : Byte;
    Hi : Byte;
end record;
for Double_Byte_Type use record
    Lo at 0 range 0 .. 6;
    Hi at 0 range 7 .. 15;
end record;  
for Double_Byte_Type'size use 16;

function to_int_16 is new Ada.Unchecked_conversions
   (Source => Double_Byte_Type,
    Target => Interfaces.Unsigned_16);

type Some_Type is record
   Hi_Lo : Double_Byte_Type;
   -- more stuff
end record;


One advantage of this version is it should take no code. One drawback
is you have to get the byte-endianness right.

-- 
-- Stephe