handing over args from assembler to c

Altera_Forum · ‎12-22-2005

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

Altera_Forum · ‎12-22-2005

declaring ExceptionAddr and ExceptionType as volatile did't work either.

Altera_Forum · ‎12-22-2005

Can you please post the disassembly version of the function?

Paolo

Altera_Forum · ‎12-22-2005

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>

}

Altera_Forum · ‎12-23-2005

yes, at a first look they seem ok...

Paolo