Re: Emulating a 64-bit long with only 32 bits: code anyone?

On 30 May 2001 00:21:12 -0400, Sean Luke
<seanl@jifsan.cs.umd.edu> wrote:


>hoping that someone may know where you can find open source for code which
>manipulates 64-bit longs (multiply, divide, subtract, add, shift, bitwise
>and logical operations, etc.) using only 32 bits


Sorry, I don't have code for you ... I was looking for some myself a
while back. The project requirements changed and I abandoned the
search before finding anything useful (to me).


If you want any performance at all, you'll have to drop into assembler
which is necessarily machine specific. High level languages don't
allow access to the CPU flags and trying to do multiple precision
arithmetic without overflow detection and carry is *slow* and painful.


Addition and subtraction are easy in assembler, the others not so much
depending on the native instruction set.


Good luck!


George Neuner
Automated Visual Inspection Systems, Inc.

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