Faster Division

[Richi]

Hi Guys,
anyone an idea how I can do that faster:

output_high(OUTPUT_2);
MERKER_16_2 = MERKER_32 / MERKER_16_1;
output_low(OUTPUT_2);

I measured the time between with the Oscilloscope

16 and 32 are for long and double and this operation takes 1,1ms with a 4MHz clock!!!

Is it possible to do this faster? Some special algorytm?
I think with a the method subtraction it is not faster

Thanks

[Moldy Green Bread]

[Richi]

... I´m still using a PIC16F819 you meant: use a PIC18F...?

I would, but no space. Now I try to use the internal clock - 8MHz

What about the assembler? I can implement assembler code- so do you have a programm for me? I not good in assembler.

[ckielstra]

I'm not sure, but it is possible that CCS implements the division as int32/int32. Faster would be to do it as int32/int16 but it sounds logical for CCS not to provide seperate functions for all possible bit combinations (optimizing memory usage over speed).

Have a look at http://www.piclist.com/techref/microchip/math/div/index.htm for several (assembly) math routines.

Maybe a further optimization is possible for your application by using the int24/int16 routine from that same website?

[SherpaDoug]

Maybe you can calculate

X = 1/MERKER_16_1;

at some non-time critical point in the code. Then using this may be faster.

MERKER_16_2 = MERKER_32 * X;
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