detect overflow of multiply/ div32 result

[richard]

its mainly about speed of execution and code size.

eg miles to kilometre conversion k=m*1.609

pbp has no floats so the 1.609 needs to be scaled up and then the result scaled back

this will work :-
you could do 1.609*1000=1609

k=m*1609 /1000

(k=m*1609
div32 1000)


this is better :-

using 1.609 * 256 = 411
so k=m*411/256 (eq to k=m*/411)

and will give you smaller faster code
and has a larger input range before overflowing also

[ruijc]

Thanks for the explanation Richard,

It's crystal clear now

Regards
Rui