Frequently Asked Questions

How much time do math operations take?

Unsigned 8 bit operations are quite fast and floating point is very slow. If possible consider fixed point instead of floating point. For example instead of "float cost_in_dollars;" do "long cost_in_cents;". For trig formulas consider a lookup table instead of real time calculations (see EX_SINE.C for an example). The following are some rough times on a 20 mhz, 14 bit PIC. Note times will vary depending on memory banks used.

8 bit add	<1 us
8 bit multiply	9 us
8 bit divide	20 us
16 bit add	2 us
16 bit multiply	48 us
16 bit divide	65 us
32 bit add	5 us
32 bit multiply	138 us
32 bit divide	162 us
float add	32 us
float multiply	147 us
float divide	274 us
exp()	1653 us
Ln()	2676 us
sin()	3535 us