Nios II Program Counter

Altera_Forum · ‎09-12-2008

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

Altera_Forum · ‎09-12-2008

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

Altera_Forum · ‎09-12-2008

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

Altera_Forum · ‎09-17-2008

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 · ‎09-17-2008

You can only read it via the nextpc instruction.

From the NIOS II instruction set reference:


nextpc
get address of following instruction
Operation: rC &#8592;  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