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Altera_Forum's avatar
Altera_Forum
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12 years ago

How to read NIOS-II General Purpose Register's

How to read NIOS-II General purpose Register specifically r29 (Exception return Address) & r30 (Breakpoint return Address)

NIOS-II Processor Reference Handbook Page 3-11

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  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    If you are working in C, you may need to create a function in assembly language.

    See nios2.h and the macros for NIOS2_READ_ET(), NIOS2_WRITE_ET() which operate on register R24 (Exception temporary). I suppose you just need to clone those, but substitute the appropriate register identifier in the assembly language.
  • Altera_Forum's avatar
    Altera_Forum
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    12 years ago

    GCC generated code will often save r29 on the stack, and then use r29 as a temporary register.

    Similary the assembler breakpoint stub will save r30 somewhere.

    So the values in the registers are very boring in any C code.