Re: AVR Usart send number string with no 'Image

["Rego, P." <pvrego@gmail.com>]

On Wednesday, May 1, 2013 7:32:42 PM UTC-3, Shark8 wrote:
>     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;

Thanks Shark8, even better than my last one.