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Re: [Caml-list] Runtime overflow and what to do
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Date: -- (:)
From: Pierre Weis <pierre.weis@i...>
Subject: Re: [Caml-list] Runtime overflow and what to do
> Hi,
> 
> On Sun, Oct 13, 2002 at 11:25:37AM +0200, Xavier Leroy wrote:
> 
> > Multiplication is left as an exercise for the readers :-)
> 
> Much more complicated... I tried that a long time ago when I was
> writting a PostScript interpreter, but I found no solution.

(* [lenght_of_int] is the maximum number of bits in an integer. *)
let length_of_int = Sys.word_size - 2;;

let ( * ) n m =
 if num_bits_int n + num_bits_int m < length_of_int
 then n * m else raise (Overflow ("*", string_of_int n, string_of_int m))

(* [num_bits_int n] returns the number of significant bits of an
   integer. *)

Just to let people play with the writting of the module :),
num_bits_int is left as an exercise to the interested readers (3 lines
of Caml code using trivial bit shuffling).

Pierre Weis

INRIA, Projet Cristal, Pierre.Weis@inria.fr, http://pauillac.inria.fr/~weis/


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