Lock using static libraries *.a

[luluv1]

Hello,

I would like to link a static library into my Arduino project. I have tested it for SAMD and AVR respectively ( Arduino Uno et Arduino Zero)

I have already read this topics:
https://arduino.stackexchange.com/questions/57891/how-to-use-a-precompiled-library-in-a-project-with-arduino-ide
https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5:-Library-specification#libraryproperties-file-format
arduino/Arduino#4336

I follow the instruction in order to add static library, then I can see it in the Contributed library (attached file)

Here is the source code of my compiled library :
int foo(void) { return 1; }

Then, I create a library using ar tool.

I create a repo called foo which include

• library.properties
• and a repo src as below:
  -/src
  ---foo.h
  ---/{architecture_mcu_name}
  -----libfoo.a

author=lululuv1
maintainer=foo <foo@gmail.com>                                                                          
sentence=                                                                                                
paragraph=                                                                                              
category=Uncategorized                                                                                  
url=                                                                                                    
architectures=*                                                                                          
precompiled=true                                                                                        
ldflags=-lfoo`

My foo.h contain the function prototype : int foo(void);

FInally I create the ino project, include the library....

#include <foo.h>

void setup() {
  Serial.begin(9600);
}

void loop() {
  int foo_value = foo();
  Serial.print("FOOFOOFOOFOOF");
}

Link with the library is done because if I want to link a libfoo.a from a dismatch architecture I got an error.

Hence, there is no compilation error, no link error but when i call the function foo(); I am lock, the print FOOFOOFOOFOO is never done.

Any idea ?

Thank you
PS: this is a simple example in order to reproduce the problem, can be done with avr-gcc or arm-none-eabi-gcc

[kgoveas]

Hi,

Check out the readme in https://github.com/BoschSensortec/BSEC-Arduino-library

[facchinm]

Hi @luluv1 ,
I can't see what could be wrong with your setup; could you try a simple hack to understand if the problem is with the lib you are linking?
1 - remove precompiled=true for your library.properties and add dot_a_linkage=true
2 - add a C/C++ file with foo() implementation
3 - compile the example once

This will produce a .a archive of the library that you can copy back to the lib folder; after undoing the changes (remove implementation file and readding precompiled flag) should result in the same outcome.

Let me know if it works or there's any improvement!

[luluv1]

Thank you @facchinm ,

I did all the steps. Using a foo.cpp, it creates a foo.a in the tmp folder.
I try to use this one, compilation is ok. I can upload the code but there is no improvement... I did this test using Arduino M0 Pro

I attach the library created using dot_a_linkage -> libfoo.zip

Thank you very much for your help,

[facchinm]

Hi @luluv1 ,
I tested your .a and it works just fine in my setup (SAMD core 1.8.1). I'm attaching the "full" library so you can test too in your setup
libfoo.zip
Let me know if it works for you!

[luluv1]

Hi @facchinm ,

You are right, it works fine.
When arduino create the foo library, it use the same compilation flag...

My mistake when I create the foo library on my own.
---> I do not use the -mthumb flag unlike the arduino compilation

Also, I find another interesting point. (Which is maybe obvious for you)
In my library (not the foo library but a real one ;-) there is an (useless) empty main function. I guess that Arduino consider this main as the entry point. Hence, nothing happen...

Thank you for your help.