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STC backup registers

Burim Aliu
Intellectual 510 points

Hi

Before the STC test is executed the CPU registers must be saved on the stack

I am running the STC during runtime but after restoring the registers i am getting an exception which i cant reproduce

because after the STC starts all breakpoints are removed....

Does anybody has sample backup code?, maybe i don't backup all registers

Regards 

Burim

  • 0
    TI__Guru**** 196776 points

    Hi Burim,

    Enclosed code is to backup stackpointer. They are stored in RAM, and should be restored after STC.

    Regards,

    QJ

    =================================

    coreBackupStackPointer_:

     

    ldr r0, r1_bkup

    str r1, [r0]

    ldr r0, r2_bkup

    str r2, [r0]

     

    msr cpsr_c, #0xD1

    ldr r0, fiq_bkup

    str sp, [r0]

    msr cpsr_c, #0xD2

    ldr r0, irq_bkup

    str sp, [r0]

    msr cpsr_c, #0xD7

    ldr r0, abort_bkup

    str sp, [r0]

    msr cpsr_c, #0xDB

    ldr r0, undef_bkup

    str sp, [r0]

    msr cpsr_c, #0xDF

    ldr r0, user_bkup

    str sp, [r0]

    msr cpsr_c, #0xD3

    ldr r0, svc_bkup

    str sp, [r0]

    bx lr

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

    user_bkup: 

     

     

    svc_bkup:

     

     

    fiq_bkup:

     

     

    irq_bkup:

     

     

    abort_bkup:

     

     

    undef_bkup:

     

     

    r0_bkup:

     

     

    r1_bkup:

     

     

    r2_bkup:

     

     

     .word 0x08001020     .word 0x0800101C     .word 0x08001018     .word 0x08001014     .word 0x08001010     .word 0x0800100C     .word 0x08001008     .word 0x08001004     .word 0x08001000

  • 0 in reply to QJ Wang
    Intellectual 510 points

    Hi  

    This backup function is taking care of just the [0-7] bits of the CPRS

    Should be taken care of the "E- data endianness bit" too? I am confused about that

    Regards

    Burim

  • 0 in reply to Burim Aliu
    TI__Guru**** 196776 points

    Hi Burim,

    Yes. The CPSR register should also be taken care of.

    Regards,

    QJ