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From: hunt@spar.SPAR.SLB.COM (Neil Hunt)
Newsgroups: comp.lang.c
Subject: Re: We need  H E L P (!!!!) with an algorithm.
Message-ID: <1460@spar.SPAR.SLB.COM>
Date: Tue, 13-Oct-87 13:59:07 EDT
Article-I.D.: spar.1460
Posted: Tue Oct 13 13:59:07 1987
Date-Received: Thu, 15-Oct-87 00:50:52 EDT
References: <116@fxgrp.UUCP>
Reply-To: hunt@spar.UUCP (Neil Hunt)
Organization: Schlumberger Palo Alto Research - CASLAB
Lines: 29

In article <116@fxgrp.UUCP> ljz@fxgrp.UUCP (Lloyd Zusman) writes:
>Has anyone out there come across any algorithms for doing arithmetic on 64-bit
>integers?  In other words, we want to define a new data type something like
>this ...
>
>        typedef struct {
>                unsigned long low_order;
>                unsigned long high_order;
>        } ExtPrecision;
>
>Then, we want to be able to do addition, subtraction, multiplication, and
>division on these ExtPrecision things.  Furthermore, we need to be able to
>convert between these things and ASCII strings so they can be input and
>output from a terminal.

If you are on a UNIX machine, I hope that you looked at MP(3)

  MP(3X)	MISCELLANEOUS FUNCTIONS       MP(3x)

  NAME
    mp, itom, madd, msub, mult, mdiv, mout, pow, gcd, rpow,
    xtom, mtox, mfree - multiple prevision integer arithmetic.

It is written in C (at least all the bits I looked at), and based upon
the algorithms in Knuth2, with references.

Hope this helps.

Neil/.