System_printf supported format specifications

Juan R. Garcia

Hi,

I have an application that needs to print out some float values. I have tried using System_printf but it seems not working. If I specify %f all I get is an f printed out. It happens the same for %F. I have been searching inside the target configuration file, in the System and SysMin sections, but I have found nothing.

By the way, printf (imported from stdio.h) does print out float values.

Thank you very much.

over 13 years ago

0 Gordon Deane over 13 years ago

Expert 1255 points

RTSC considers the %f an 'extended format' which is not compiled in by default. Add to your config file:

System.extendedFormats = '%$L%$S%$F%f';

(%$S, %$F etc. are useful if you want to use xdc.runtime.Log and xdc.runtime.Error). System_printf is an entirely separate implementation from the C runtime printf, for various reasons.

The XDC docs for System_printf do explain this, but could perhaps be a bit a clearer example in the case of enabling %f, which seems a common thing to want on a floating-point DSP...

0 Juan R. Garcia over 13 years ago in reply to Gordon Deane

Prodigy 70 points

Thank you very much. I'm kinda newbie and the platform is huge; ccs integrates everything very well though.

0 Jeremy Downing over 12 years ago in reply to Juan R. Garcia

Prodigy 30 points

What about %g and %e? I tried simply appedning

System.extendedFormats = '%$L%$S%$F%f%g%e';

but that doesn't seem to work.

0 ToddMullanix over 12 years ago in reply to Jeremy Downing

TI__Guru* 96960 points

Jeremy,

%g and %e are not supported. From the System_printf documentation:

"This function behaves much like the ANSI C Standard printf but does not support the full range of format strings specified by the C Standard. In addition, several non-standard format specifiers are recognized."

This was done to keep the code footprint small.

Todd

0 Jeremy Downing over 12 years ago in reply to ToddMullanix

Prodigy 30 points

Where can I read in code or documentation the full list of supported format speficiers?

0 ToddMullanix over 12 years ago in reply to Jeremy Downing

TI__Guru* 96960 points

Hi Jeremy,

Unfortunately it is this is documented...and it should be. I've opened a bug report on it: https://bugs.eclipse.org/bugs/show_bug.cgi?id=404046

You can look at code in <xdctools_install_dir>\packages\xdc\runtime\System.c. In the System_doPrint() function, there are lots of "if (c ==" statements that show which options are supported. Also if you do not provide a different extendFxn function (I expect you are not), the System.xdt file has "if (c ==" statements also that show the extended options. The .xdt file is a template that has JavaScript and C code. It gets converted to standard C code during the build and placed in the big generated .c file that is compiled with your application (it is in the debug\configPkg\package\cfg directory). The template allows us to generate optimal code based on your configuration.

Todd

0 Jeremy Downing over 12 years ago in reply to ToddMullanix

Prodigy 30 points

Excellent, thank you.

0 Sasha Slijepcevic over 12 years ago in reply to Jeremy Downing

TI__Mastermind 37985 points

Jeremy,
conversion specifiers are documented here: http://rtsc.eclipse.org/cdoc-tip/xdc/runtime/System.html#printf. Is that what you were looking for?

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System_printf supported format specifications