Re: touchscreen calibration again

Hi Zap,

>Wh... wh... what??? floating-point? kidding? Floating point is a performance
>killer on ARM, especially in the kernel! Every fp operation causes a exception
>and a lot of overhead.
>
>

Oops... I knew that floating point operations had to be emulated on ARM,
but not that each one corresponded to a kernel exception.

>Use fixed-point math. With 16.16 fixed-point you'll get ~0.000015 accuracy,
>and you can represent with 32 bits any number in the range 0.0-65535.9999.
>With 14.18 fixed-point you'll get ~.000004 accuracy, and you can represent
>with 32 bits any number in the range 0.0-16383.99999. I think this is quite
>enough for touchscreen readings.
>
>I can explain how to use fixed-point arithmetic, if somebody is interested.
>
>
Sure! Please go ahead! I will need this to write the h2200_lcd driver.

Thanks a lot for clarifying this!

    Have a nice day,

    :-)

    Michael.

-- 
Michael Opdenacker
http://opdenacker.org/