Re: Bit Manipulations

[Mats Weber <matsw@mail.com>]

generic
   type T is private;
function bitwise_and (left, right : T) return T;

function bitwise_and (left, right : T) return T is
   type bit_array_t is array (1 .. T'Size) of Boolean;
   pragma Pack (Bit_Array_T);
   function to_t is new unchecked_conversion(bit_array_t, t);
   function to_bit_Array is new unchecked_conversion(t, bit_array_t);
begin
   return to_t(to_bit_array(left) and to_bit_array(right));
end;

Then create "and" operators for the types you need, e.g.:

type my_int is range -34 .. 2222;

function "and" is new bitwise_and(character);
function "and" is new bitwise_and(integer);
function "and" is new bitwise_and(my_int);

> For instance, I get a byte from a hardware port and want to mast off the
> parity bit ( 16#07F#).
> 
> I want to do...
> 
> char_data := char_data AND 16#07F#

or, simpler:

if character'pos(char_data) > 127 then
   char_data := character'val(character'pos(char_data) - 128);
end if;