Arbitrary Length Math with a 56F8013

jag — Tue, 26 Sep 2006 18:35:03 GMT

Hi,
for a program I'm doing I need to do some math with very large numbers.
Very large numbers means 64 bits (signed) variables.
Just to be clear: it is not my decision to use 64 bit variables.
The problem is, as I think you have understood, that the 56800/E can NOT use 64 bit variables, but "only" 32 bits.
So I need to split the 64 bit variable in 2 chucks of 32 bit each, and do the math (only + and - luckily) with these 32 bits chucks.
Now I'm wondering if exist some algorithm already implemented for the 56800/E that do this kind of math.
Or else I'll write it, but I've no uidea how to manage the overflow (and underflow) of the low chuck.

Thanks Bye Jack

Re: Arbitrary Length Math with a 56F8013

jag — Tue, 26 Sep 2006 20:10:35 GMT

I reply to myself .

The 56800/E core can do 64 bit addition and subtraction (cfr. pag. 5-29 of DSP 56800E Reference Manual).

So problem solved. Or at least I don't have to implement the algorithm myself.
Now I just have to search for the C function (or write the assembler routine in my C code).

Bye Jack

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Arbitrary Length Math with a 56F8013

Re: Arbitrary Length Math with a 56F8013