AN 978: Nios® V Processor Migration Guidelines

ID 773196
Date 1/27/2025
Public
Document Table of Contents

7.4. Miscellaneous Operations

Table 42.  Assembly Language Comparison (Miscellaneous Operations)
Nios® II Processor Nios® V Processor
Operation Assembler Syntax Operation Assembler Syntax

Debugger Breakpoint

break Debugger Breakpoint ebreak

Debugger Breakpoint Return

bret Debugger Breakpoint Return dret
Custom Instruction custom N, rC,rA, rB Custom Instruction

Refer to custom_instruction_debug.xml to write the machine code. For example, “.4byte 0xe7978b”.

Note: If you use custom instructions to generate the BSP, you can find the .xml file in the BSP Project folder.

status ← estatus

PC ← ea

eret PC ← mepc mret
rC ← PC + 4 nextpc rC

xC ← PC + 4

PC ← PC + 4

jal xC, 4

No Operation

nop No Operation nop

Read from Control Register

rdctl rC, ctlN Read from Control Register csrr xC, csr

Read from Previous Register Set

rdprs rB, rA, IMM16 Not available in Nios® V processor -

Return from Subroutine

ret Return from Subroutine ret
Trap trap Trap ecall

Write to Control Register

wrctl ctlN, rA Write to Control Register csrw csr, xC

Read to Previous Register Set

wrprs rC, rA Not Available in Nios® V processor -