This is project presents a small tutorial for a technique to automatically store and load designated variables with minimal hassle for the programmer. The variables can be declared normally, without massive amounts of serialization or deserialization code.
The method is not without limitations or problems, but it is quick and simple to implement.
The tutorial is written in nvram.c, this file should be viewed to see how it works, spoiler - get your linker to put your variables in a custom section and write this to disk using atexit.
This code works with either GCC or Clang.
To build and run the program:
make nvram
make run
When run, the nvram program will attempt to load a file off disk called "nvram.blk", if it cannot do that then the default values as specified in the C source code are used.
The variables get written back to disk on program exit, the demonstration program does nothing fancy, it is simply there to illustrate the technique.
This program has to be run multiple times to see any affect.
A hacked together editor using doxygen and perl has been added, it is another demonstration of a concept. The editor script, editor.pl, takes as its input two files, an XML file produced by doxygen which contains a processed version of nvram.c. The declarations are easily extractable from this XML file (the perl module TreePP does the parsing), and variables with the correct declaration are searched for. This used to automatically construct an editor for the "nvram.blk" file.
The editor itself is very primitive.