Nios® II Embedded Design Suite (EDS)
Support for Embedded Development Tools, Processors (SoCs and Nios® II processor), Embedded Development Suites (EDSs), Boot and Configuration, Operating Systems, C and C++
12469 Discussions

How to read NIOS-II General Purpose Register's

Altera_Forum
Honored Contributor II
1,125 Views

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
0 Kudos
2 Replies
Altera_Forum
Honored Contributor II
130 Views

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
Honored Contributor II
130 Views

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.
Reply