On 12/08/2019 08:37, David Binderman wrote:
Hello there,
Source code is
prescale = 15;
base = timer_base * (1 << prescale);
divider = 65535;
*nanosec = divider * base;
timer_base seems to be 500 or 100.
nanosec is a pointer to int, so it can only hold about 2,000,000,000 nanoseconds, or about 2 seconds.
Thanks for the report.
I couldn't reproduce the error with the compiler version I was using,
but I can see that it is likely to result in an arithmetic overflow.
I think the main problem is that the line (in (dt3k_ns_to_timer()):
base = timer_base * (1 << prescale);
should be:
base = timer_base * (prescale + 1);
which matches the earlier instance of this calculation in the same function.
In practice, these lines of code should never be reached due to earlier
range checks in dt3k_ai_cmdtest().
Suggest rework code to use longs.
It wouldn't do any harm to change the `int` variables to `unsigned int`.
Regards
David Binderman
time-_Base seems to be 50 or 100.
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