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Altera_Forum's avatar
Altera_Forum
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17 years ago

Nios II Program Counter

Is there anyway to access the Nios program counter from the hardware (instead of using instruction like nextpc..) ? :confused:

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    Nice question, sorry I can not help you but I can suggest you to post your question to the Nios Forum.

  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    I already posted the question there 2 months ago but seems no reply so far...:(

  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    Why do you need it? What will you do with it?

    If you say accessing it? Is it access in software, or in hardware?

    Stefaan
  • Altera_Forum's avatar
    Altera_Forum
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    17 years ago

    You can only read it via the nextpc instruction.

    From the NIOS II instruction set reference: 

    
nextpc
get address of following instruction
Operation: rC ←  PC + 4
Assembler Syntax: nextpc rC
Example: nextpc r6
Description: Stores the address of the next instruction to register rC. 
Usage: A relocatable code fragment can use nextpc to calculate the address of its data 
segment. nextpc is the only way to access the PC directly.
Exceptions: None
Instruction Type: R
Instruction Fields: C = Register index of operand rC

    Obviously you can modify the program counter via jump and branch commands.

    Jake