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Re: New Vax - future directions :-)

>> If you have two 64-bit values which you multiply, there is a fair
>> chance the result will not fit into 64 bits, and a carry won't be
>> enough to handle the overflow. :-)  Then what?  Just give up.  Leave
>> it all to be done in software?  Or add some instruction that can
>> assist you?
> Yes, do it in software.

I've done multiprecision arithmetic without special instruction assist
(for that use case, code portability won over performance, so I did it
all in C.)

It's cumbersome and comparatively slow.  I ended up resorting to
half-size multiplies (ie, half the size of the largest integer the
language provided).

> You don't have any modern language that want to deal with the upper
> part anyway.

Maybe not - I don't know "modern language"s - but any Lisp system with
bignum support, or any modern crypto, wants to do arithmetic on
integers having hundreds-to-thousands of bits.

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