DSR not called

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originally posted by tns1@Nov 9 2005, 10:42 AM

if the code looks ok, what about the state of the registers?

to learn more, try explicitly disabling interrupts around the dsr "abe++".

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The problem has been located.

Stepping through the assembler code I noticed that the index into the hal_interrupt_data is calculated and stored in r15.

Then a call to the isr takes place and upon return r15 is used again for finding the DSR and calling the interrupt_end function.

If the ISR uses r15 without restoring it this scenario will obviously crash in many flavours http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif

In the broken code r15 is used by the compiler and not restored which is perfectly legal according to the register usage table 7-2 in nios ii processor reference handbook.

Depending on the kind of C code you write in the ISR you can have r15 corrupted or not.

I&#39;ve just modified the vector.s code to use r16 instead of r15 pushing it onto the stack etc and that did the trick.

in my humble opinion this seems to be a major bug in the nios port of ecos.

Looking forward to having your opinions.