Honored ContributorI write a very simple program, driving LED through PIO. Both function can work. If using main() , the code size is 1940 bytes. If alt_main(), the code size is 472 bytes. It seems that main() include some initialization.
Can anyone explain the difference, or recommend some documents to read? Thanks.
Honored ContributorActually it is the default alt_main() that contains the extra code - either side of the call to main().
Largely this is code for initialising stdio for printf() - which pulls in a lot of library code.Honored ContributorHi sabertooth
I copy here the comment to alt_main() definition /* * alt_main is the C entry point for the HAL. It is called by the assembler * startup code in the processor specific crt0.S. It is responsible for: * completing the C runtime configuration; configuring all the * devices/filesystems/components in the system; and call the entry point for * the users application, i.e. main(). */ RegardsHonored ContributorMany thanks to Cris72.
