Re: [freeelks-devel] Class BASIC_ROUTINES

[Eric B. <er...@go...>]

Eric Bezault wrote:
> I know that BASIC_ROUTINES does not belong to the core of
> the kernel classes, but since it is here, I had a look at
> it. I was wondering if it would be possible to get rid of
> the 3 external routines of this classe and write it in
> pure Eiffel. For `charconv' I think that we can write:
> 
>     charconv (i: INTEGER): CHARACTER is
>             -- Character associated with integer value `i'
>         do
>             if i.is_valid_character_code then
>                 Result := i.to_character
>             end
>         end
> 
> The difference I see is that it returns a null character
> if the integer value is out of bound, instead of some
> other value. Do we care?

In fact the following implementation gives the same
behavior as the external routine, even for out-of-bound
values:

	charconv (i: INTEGER): CHARACTER is
			-- Character associated with integer value `i'
		do
			Result := (i & 0x000000FF).to_character
		end

> For `bottom_int_div' and `up_int_div', I must say that not
> having the C code of 'bointdiv' and 'upintdiv' I don't
> know exactly what they are supposed to do. Could they be
> written in pure Eiffel as well?

I made some tests and the following implementation seems to
give the same results as the external routines:

	bottom_int_div (n1, n2: INTEGER): INTEGER is
			-- Greatest lower bound of the integer division of `n1' by `n2'
		local
			r: INTEGER
		do
			Result := n1 // n2
			r := n1 \\ n2
			if n2 > 0 then
				if r < 0 then
					Result := Result - 1
				end
			elseif r > 0 then
				Result := Result - 1
			end
		end

	up_int_div (n1, n2: INTEGER): INTEGER is
			-- Least upper bound of the integer division
			-- of `n1' by `n2'
		local
			r: INTEGER
		do
			Result := n1 // n2
			r := n1 \\ n2
			if n2 > 0 then
				if r > 0 then
					Result := Result + 1
				end
			elseif r < 0 then
				Result := Result + 1
			end
		end

-- 
Eric Bezault
mailto:er...@go...
http://www.gobosoft.com