On Fri, 1 Feb 2002, Edson Brusque wrote:

> Hello,
>
>     I need to multiply a byte by another byte and then divide this result by
> 255, like x = y * z / 255.
>
>     At this moment, I'm using CCS-PICC built-in maths, but it's very
> inneficient. The execution time for this calculation is about 1200
> instructions(!).
>
>     Someone have an idea of a very fast math function in assembly to make
> this?


This can be done in less than 40 cycles. Is that fast enough?

Hint: look at the http://www.piclist.com/

And remember that 1/255 = 1/256 + 1/256^2 + 1/256^3 ...

When done, I promise this will not take anywhere near a ridiculus 1200
cycles on SDCC. OTOH, I don't think it take just 40 either...

Scott

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