Enhance NRF LOG to include line number in prefix

RE: Enhance NRF LOG to include line number in prefix

Andy — Wed, 06 Mar 2019 10:18:45 GMT

Mm I think this will have the same issue as with the macro, i.e. the arguments won't get parsed.

RE: Enhance NRF LOG to include line number in prefix

awneil — Wed, 06 Mar 2019 10:05:02 GMT

in your header:

static inline void log_with_location( char * stuff )
{
   NRF_LOG_INFO("%-25s:%4d:%8lu: %s", __FILE__, __LINE__, timestamp(), stuff );
}

in your code:

#include "log_with_location.h"

:
:

   log_with_location( stuff ); // If __LINE__ and __FILLE__ get expanded here, 
                               // they will refer to this location!

:
:

RE: Enhance NRF LOG to include line number in prefix

Andy — Tue, 05 Mar 2019 18:06:07 GMT

Assuming that it works, what would the inline function look like?

RE: Enhance NRF LOG to include line number in prefix

awneil — Tue, 05 Mar 2019 18:05:02 GMT

like I said, it depends on when the __FILE__ and __LINE__ get expanded in an inline file - it's only useful if they get expanded at the point where the function is inlined (ie, the call).

RE: Enhance NRF LOG to include line number in prefix

Andy — Tue, 05 Mar 2019 18:02:18 GMT

Yeah, calling NRF_LOG_INFO multiple times (which is what I don't want to do):

#define debug(...) do { NRF_LOG_INFO("%-25s:%4d:%8lu: ", __FILE__, __LINE__, timestamp()); NRF_LOG_INFO(__VA_ARGS__); } while(0)

How would an inline function call be different? What would it look like?

RE: Enhance NRF LOG to include line number in prefix

awneil — Tue, 05 Mar 2019 17:15:31 GMT

But that's macros - I'm talking about a proper function call.

For macros, you'd have to get down & dirty with the stringification stuff ... ?

😮

But you said you already had this working with macros?

RE: Enhance NRF LOG to include line number in prefix

Andy — Tue, 05 Mar 2019 16:34:08 GMT

i.e. if I called debug("x = %d", x); it would print

main.c: 100: 23: x = %d

RE: Enhance NRF LOG to include line number in prefix

Andy — Tue, 05 Mar 2019 16:32:24 GMT

I already tried something like that:

#define debug(...) NRF_LOG_INFO("%-25s:%4d:%8lu: %s", __FILE__, __LINE__, timestamp(), __VA_ARGS__)

But the arguments weren't being processed.

RE: Enhance NRF LOG to include line number in prefix

awneil — Tue, 05 Mar 2019 16:24:11 GMT

I was thinking of making the inline function the thing that you actually place in your code - so the line where it's called is the one you want

RE: Enhance NRF LOG to include line number in prefix

Andy — Tue, 05 Mar 2019 16:15:28 GMT

Mm I'm not sure, but neither of those cases is useful to me. It will either always show the line where it was defined, or it will always show the line where it was called (which would always be in nrf_log_frontend.c)

RE: Enhance NRF LOG to include line number in prefix

awneil — Tue, 05 Mar 2019 15:13:31 GMT

Just a thought:

If you use an 'inline' function, do __FILE__ and __LINE__ expand according to where the function was defined, or where it was inlined (called) ... ?

RE: Enhance NRF LOG to include line number in prefix

Andy — Tue, 05 Mar 2019 14:44:48 GMT

To be more specific, how would I create a function that returns different line numbers of calls that happened elsewhere in the code?

RE: Enhance NRF LOG to include line number in prefix

Andy — Tue, 05 Mar 2019 14:43:25 GMT

How would I use that?

RE: Enhance NRF LOG to include line number in prefix

Simonr — Tue, 05 Mar 2019 14:27:19 GMT

I don't know if this is what you're after, but maybe you'd want to modify an already existing function, I.E. modify the NRF_LOG USES_TIMESTAMP function to instead of timestamps, output the line you want. Or at least use that function as a template.

Best regards,

Simon

RE: Enhance NRF LOG to include line number in prefix

Andy — Tue, 05 Mar 2019 14:18:49 GMT

At least not without creating a wrapper macro that calls NRF_LOG_INFO twice, which is what I already did.

RE: Enhance NRF LOG to include line number in prefix

Andy — Tue, 05 Mar 2019 14:17:42 GMT

Yeah, that's basically what I want to do, but it's not trivial as far as I can tell.

RE: Enhance NRF LOG to include line number in prefix

awneil — Tue, 05 Mar 2019 14:10:26 GMT

Yes, I would say you'd have to pass __LINE__ as parameter, and have your formatter put that into the string...

Something like this:

https://stackoverflow.com/a/15885297/4618900

EDIT

Fix link

RE: Enhance NRF LOG to include line number in prefix

Andy — Tue, 05 Mar 2019 14:00:19 GMT

And I think I'd have to modify starting from the macros, inserting __LINE__ somewhere.

If I add __LINE__ somewhere in the string formatter module it will print the line in that source file, not the line where the NRF_LOG_INFO macro was initially called from.

RE: Enhance NRF LOG to include line number in prefix

Andy — Tue, 05 Mar 2019 13:50:59 GMT

I know I have to modify the source... I'm asking for some hints about what to modify. The logging module is kind of like a cascade of macros. One after another after another.

RE: Enhance NRF LOG to include line number in prefix

awneil — Tue, 05 Mar 2019 13:43:50 GMT

[quote userid="15909" url="~/f/nordic-q-a/44436/enhance-nrf-log-to-include-line-number-in-prefix"]What would be the best way to do this?[/quote]

Examine the source of the existing logging functions, and modify to suit.

Only the string formatting should be affected - not the transmission functions.

You will probably need to understand how variadic functions work in 'C' ...

https://en.cppreference.com/w/c/variadic