How to generate .a and .so files to add in arduino project

Question

I know to make a library on arduino ide with source codes, but I cant send my source code to another users who want to use my lib.

So I need to make a library with precompiled=true info at library.properties. And I need to put my .a and .so files at src/{build.mcu} (in my case, src/avr/mylib.a and mylib.so).

But, where is that files (.a and .so)?!

Does the arduino compiler generate this files? If so, where? If dont, how compiler I need to use?

I found the .o file at appData\local\Temp\arduino_build_XXXX\libraries\mylib\

Thank you very much and sory about my english.

Answer 1

[library] = library name

1) edit the [library] library.properties file and add dot_a_linkage=true to the end ... (/home/name/Arduino/libraries/[library]/library.properties)

2) build the example ...

3) After the build is complete navigate to the build folder (In Linux it's located in the /tmp/arduino_build_xxxxxx folder) then copy the dot_a file from under library folder (libraries/[library].a) to the arduino library folder for the [library] library (/home/name/Arduino/libraries/[library]/src/esp8266/lib[library].a)

4) edit the [library] library library.properties file again and remove dot_a_linkage=true and add precompiled=true and ldflags=-l[library] to the end of the file ...

5) build the example ... this time it links to the dot_a file ...

Answer 2

• Note: I have never done this with the Arduino IDE, so I don't know if the resultant file will be of any use to you.

A .a file (you don't want a .so file - that's a shared library that makes no sense on a platform without an OS) is merely an archive (ar archive, specifically) that contains one or more .o files.

You create one simply enough using:

avr-ar rcs myLib.a myLib.o

You will find the avr-ar program in the tools installation within your Arduino IDE somewhere.

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As an aside, UECIDE (which I wrote) uses library files like these to cache its libraries and other compiled code. You can use UECIDE to directly grab a .a file for your library, which you would find in the cache folder of the UECIDE data folder (find it through the Help -> Debug menu).

Answer 3

Thank you Majenko!

But, the program is not avr-ar for me, I use the avr-gcc-ar.

After that, I must to dot_a_linkage=true in my library.properties and manually add mylib.a at AppData\Local\Temp\arduino_build_115676\libraries\mylib\

I dont know why, but this help for me.

I hope help other.

Best regards.