How to Use Overrides for Static Library Build?

liquidsoulder · October 13, 2020, 9:32pm

Hi there - I am trying to enable floating point formatting in the minimal-printf library during a build of a static archive of mbed-os.

I am able to follow the instructions from the minimal-printf repo when building an application (using mbed_app.json), however I am unable to get the same configuration changes when building my archive.

The command I use to build my static archive:
mbed compile --library --source=mbed-os -m SFE_ARTEMIS_DK -t GCC_ARM

How may I enable floating point formatting using the minimal-printf library within a static archive build of mbed?

related github issue

Thanks a bunch!

liquidsoulder · October 20, 2020, 6:34pm

Can anyone offer insight into this? I am struggling to find the information on my own. Thank you

AnnaBridge · October 26, 2020, 5:57pm

Hi

this should help:

github.com

ARMmbed/mbed-os/blob/master/platform/source/minimal-printf/README.md

# Minimal printf and snprintf


Library supports both printf and snprintf in around 1300 bytes of flash.

Prints directly to stdio/UART without using malloc. Width size and prepending zero modifiers are supported. All other flags are ignored.
There is no error handling if a writing error occurs.

Supports:
* %d: signed integer [h, hh, (none), l, ll, z, j, t].
* %i: signed integer [h, hh, (none), l, ll, z, j, t].
* %u: unsigned integer [h, hh, (none), l, ll, z, j, t].
* %x: unsigned integer [h, hh, (none), l, ll, z, j, t], printed as hexadecimal number (e.g., ff).
* %X: unsigned integer [h, hh, (none), l, ll, z, j, t], printed as hexadecimal number (e.g., FF).
* %f: floating point (disabled by default). Precision modifier is supported (e.g. %.5f).
* %F: floating point (disabled by default, treated as %f). Precision modifier is supported (e.g. %.5F).
* %g: floating point (disabled by default, treated as %f). Precision modifier is supported (e.g. %.5g).
* %G: floating point (disabled by default, treated as %f). Precision modifier is supported (e.g. %.5G).
* %c: character.
* %s: string.

This file has been truncated. show original

Regards
Anna

liquidsoulder · October 27, 2020, 9:04am

Hello Anna,

I really appreciate that you took the time to respond to me.

You might notice that I linked to the same README file in my original post. I am able to use the “target_overrides” property in mbed_app.json when building an application (which includes the ‘main’ function definition). My trouble instead comes when I try to achieve the same override when building Mbed as a static library. The mbed_app.json in the project root no longer seems to be respected, nor do a few other locations I have tried. (Such as in the mbed-os dir itself).

Is there supposed to be a difference between overrides when compiling an app vs a static library?

See, it won’t do to modify ‘mbed_config.h’ after the fact because the library will have been compiled not to support the printf features I need. Any modifications to the config header are replaced by the auto-generated file when the build is run again.

If you can offer any additional advice it would be wonderful.

Best,
Owen

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How to Use Overrides for Static Library Build?

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