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Altera_Forum's avatar
Altera_Forum
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20 years ago

handing over args from assembler to c

Hi everybody,

maby someone of you has an explenation for this behavior?

I am calling a c function from assembler code, handing over two arguments in registers r4 and r5. So far so good.

The c function assigns these argumetns to two variables and calls another c function:

void my_exception_handler(ulong addr, ulong type)

{

ExceptionAddr = addr;

ExceptionType = type;

restart();

}

restart sends ExceptionAddr and ExceptionType to the console and restarts the system.

The assignment is not working unless I do something in advance.

Like:

void my_exception_handler(ulong addr, ulong type)

{

int etemp;

etemp = 1;

ExceptionAddr = addr;

ExceptionType = type;

restart();

}

http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/blink.gif

Any ideas?

--wolf

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    declaring ExceptionAddr and ExceptionType as volatile did&#39;t work either.

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    Both versions seem to be ok for me. What do you think?

    0104e248 g O .bss 00000004 ExceptionAddr

    0104e24c g O .bss 00000004 ExceptionType

    void my_exception_handler(ulong addr, ulong type)

    {

    102a824: defffb04 addi sp,sp,-20

    102a828: dfc00415 stw ra,16(sp)

    102a82c: df000315 stw fp,12(sp)

    102a830: d839883a mov fp,sp

    102a834: e1000015 stw r4,0(fp)

    102a838: e1400115 stw r5,4(fp)

    int etemp;

    etemp = 1;

    102a83c: 00800044 movi r2,1

    102a840: e0800215 stw r2,8(fp)

    ExceptionAddr = addr;

    102a844: 00c04174 movhi r3,261

    102a848: 18f89204 addi r3,r3,-7608

    102a84c: e0800017 ldw r2,0(fp)

    102a850: 18800015 stw r2,0(r3)

    ExceptionType = type;

    102a854: 00c04174 movhi r3,261

    102a858: 18f89304 addi r3,r3,-7604

    102a85c: e0800117 ldw r2,4(fp)

    102a860: 18800015 stw r2,0(r3)

    restart();

    102a864: 01000404 movi r4,16

    102a868: 10142d00 call 10142d0 <restart>

    }

    ---

    0104e240 g O .bss 00000004 ExceptionAddr

    0104e244 g O .bss 00000004 ExceptionType

    void my_exception_handler(ulong addr, ulong type)

    {

    102a824: defffc04 addi sp,sp,-16

    102a828: dfc00315 stw ra,12(sp)

    102a82c: df000215 stw fp,8(sp)

    102a830: d839883a mov fp,sp

    102a834: e1000015 stw r4,0(fp)

    102a838: e1400115 stw r5,4(fp)

    // int etemp;

    // etemp = 1;

    ExceptionAddr = addr;

    102a83c: 00c04174 movhi r3,261

    102a840: 18f89004 addi r3,r3,-7616

    102a844: e0800017 ldw r2,0(fp)

    102a848: 18800015 stw r2,0(r3)

    ExceptionType = type;

    102a84c: 00c04174 movhi r3,261

    102a850: 18f89104 addi r3,r3,-7612

    102a854: e0800117 ldw r2,4(fp)

    102a858: 18800015 stw r2,0(r3)

    restart();

    102a85c: 01000404 movi r4,16

    102a860: 10142d00 call 10142d0 <restart>

    }