Strange value of register

adaszeq · ‎2013-02-24

Posted on February 24, 2013 at 09:08

I have one strange problem. After this fragment of code program:

b = a;

a =/ 40;

if(!a)

//breakpoints

the results of two registers are: b = 50000 - good value,

a=0

The value of a should be about 1250 not 0!!

I can't find place in my program where i change value of a, because I use it only in one place.

Any suggestion how can I find solutions of this problem?

#incorrect-expectations #wrong-value-register-bug #optimisation

Andrew Neil · ‎2013-02-25

Posted on February 25, 2013 at 10:07

You have not given enough information.

Post the smallest complete program which illustrates your problem...

luca239955_stm1_st · ‎2013-02-26

Posted on February 26, 2013 at 09:03

most likely something has been optimized away: first step is to declare the variables as volatile and see if you get the expected value.

Andrew Neil · ‎2013-02-26

Posted on February 26, 2013 at 19:46

''declare the variables as volatile and see if you get the expected value''

If you do, that may well be an indication that the expectation was flawed...

richhamersley · ‎2013-03-04

Posted on March 04, 2013 at 17:16

Did you mean: a /= 40;

i.e., a = a/40;

instead of a =/40?

a =/ 40; if accepted by compiler will always set a to 0.