Re: Image attribute (yet again)

[Shark8 <onewingedshark@gmail.com>]

On Sunday, April 26, 2020 at 8:16:46 AM UTC-6, Jere wrote:
> On Sunday, April 26, 2020 at 2:05:59 AM UTC-4, J-P. Rosen wrote:
> > Le 26/04/2020 à 00:35, Stephen Davies a écrit :
> > 'Image is not intending for elaborate formatting, it's a quick debugging
> > help. Text_IO has all formatting features for proper IO. Since every
> > program has different formatting needs, you have to write you own function.
> > 
> This might be a good time to ask since this comes up all the time
> for me, but where are the formatting options for hexadecimal 
> to String.

The method that I typically go with is something like:
Subtype Hex_Character is Character
  with Static_Predicate => Hex_Character in '0'..'9'|'A'..'F';
Type Nybble  is range 0..15 with Size => 4;
Type Byte    is record
  High, Low : Nybble;
end record with Size => 8;
-- Rep Clause.

Function To_Nybble( Input : Hex_Character ) return Nybble is
(case Input is
  when '0' => 16#0#,
  when '1' => 16#1#,
--...
  when 'F' => 16#F#
);

Function To_Hex_Character( Input : Nybble ) return Hex_Character is
(case Input is
  when 16#0# => '0',
  when 16#1# => '1',
--...
  when 16#F# => 'F'
);

Function Byte_to_Hex( Input : Byte ) return String is
( HexChar( Input.High ) & HexChar( Input.High ) );

Though for one application I made a proper Hex_Character character-type and used the 'pos/'val/'image/'value attributes.

You can also get easy string conversions with 'Value, especially:
Subtype Hex_String is String
  with Dynamic_Predicate => (for all C of Hex_String => C in Hex_Character);

Function Hex_to_Integer( Input : Hex_String ) return Integer is
( Integer'Image("16#"& Input &'#') );