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Branching to main form assembly error

sasa pavlovic
Note: This was originally posted on 25th August 2012 at http://forums.arm.com

Hey guys, do you know why a simple branch to main from the reset handler causes an hard fault? Heres an example where I try to branch to main via the reset hander in the startup file provided by Keil and this causes an

hard fault. Any cue?



Reset_Handler    PROC
                 EXPORT  Reset_Handler             [WEAK]
     IMPORT  __main
                 
                LDR     R0, =__main
                BX      R0
                ENDP
  • Note: This was originally posted on 26th August 2012 at http://forums.arm.com

    I found it, I don't know why the startup file Keilprovides load the register r0 with the address of the label __mainbut it certainly doesn't work for me. Instead, I load this register with the label main without the two
    underscores and it work perfectly.



            IMPORT  main
                     LDR     R0, =main
                     BLX     R0

                     ENDP

  • Arm Employee Badge
    Note: This was originally posted on 28th August 2012 at http://forums.arm.com

    Your solution could cause you other problems.

    The __main label is ARM's scatter loading + C library init code, which itself calls main().  So by calling main() you are by-passing the C library initialization.  This may be ok, but could lead to interesting problems.  For example, global variables probably won't have their initial values set.

    I don't know the Keil tools to know why it didn't work before.  Have you tried the dedicated Keil forums?