Re: AVR Usart send number string with no 'Image

[Shark8 <onewingedshark@gmail.com>]

On Wednesday, May 1, 2013 2:35:02 PM UTC-6, Rego, P. wrote:
> Now I am trying to implement the inverse (String to Unsigned_8),
> But the result is not right. Maybe did I forget something?

    declare
	Use Interfaces;
	Subtype Digit is Character Range '0'..'9';
	Subtype String3 is String(1..3);
	
	Function From_String(Input : String3) return Unsigned_8 is
	    Working	: String3	:= Input;
	    Index	: Unsigned_8	:= 1;
	begin
	    -- preprocessing string: spaces are treated as 0.
	    for C of Working loop
		C := (if C = ' ' then '0' else C);
		-- throw error if invalid characters exist.
		if C not in Digit then
		    raise Numeric_Error;
		end if;
		-- Note a case statement might habe been
		-- nore appropriate for this block.
	    end loop;
	    
	    Return Result : Unsigned_8 := 0 do
		for C of reverse Working loop
		    -- We add the current character's value, multiplied
		    -- by its position, to modify result.
		    Result:= Result +
			Index * (Character'Pos(C) - Character'Pos('0'));
		    -- The following works because wrap-around isn't an error.
		    -- If we weren't using Unsigned_8 we would need a cast.
		    Index:= Index * 10;
		end loop;
	    End return;
	End From_String;