On Fri, 1 Feb 2002 20:50:46 -0200, Edson Brusque wrote:

>Hello,
>
>    I need to multiply a byte by another byte and then divide this =
result by
>255, like x =3D 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?
>

If your application can tolerate about -0.4% error, you could just
take the upper byte of a 16-bit multiplication result. (Hard to get
much faster but this error may or may not meet your requirements.)

regards, Bob

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