How can I perform pre-main initialization in C/C++ with avr-gcc?

Question

In order to ensure that some initialization code runs before main (using Arduino/avr-gcc) I have code such as the following:

class Init {
public         


        

Answer 1

You can use the ".init*" sections to add C code to be run before main() (and even the C runtime). These sections are linked into the executable at the end and called up at specific time during program initialization. You can get the list here:

http://www.nongnu.org/avr-libc/user-manual/mem_sections.html

.init1 for example is weakly bound to __init(), so if you define __init(), it will be linked and called first thing. However, the stack hasn't been setup, so you have to be careful in what you do (only use register8_t variable, not call any functions).