__main in startup assembly

[Francesco Sfragara]

Posted on June 04, 2018 at 10:30

Hi.

I'm using keil for programming a stm32 board. In the start up file .s there is a call to __main after the call to SystemInit. Where is the definition of __main? What's the difference between main and __main?

[Nesrine M_O · Accepted solution]

Posted on June 04, 2018 at 10:37

Hi

IMPORT __main�?

This line refers to the __main in the C library which eventually calls the main() function defined elsewhere in your project.

-Nesrine-

[Artur IWANICKI]

Posted on June 04, 2018 at 10:40

Hello,

main is your main procedure form main.c file, once __main is an internal procedure created by Keil toolchain which is calling at the end your main, but before it is initializing all variables (copying variables from FLASH to proper positions in RAM). In gcc it is seen explicitly, in Keil you can see it within debug process.

Best Regards,

Artur

[Francesco Sfragara]

Posted on June 04, 2018 at 11:47

Thank you