AN 977: Nios® V Processor Custom Instruction

ID 773194
Date 4/14/2023
Document Table of Contents

4.2.1. Hardware Interfaces Table

You must assign the opcode and funct7 field of a custom instruction logic block. Select the symbol + to add new assignment, and - to delete. Each assignment results in a single Nios V Custom Instruction Manager interface at the processor core.

Table 11.  Hardware Interfaces Table Parameter
Parameter Description
  • The required selector index.
  • String assignment, with CUSTOM0, CUSTOM1, CUSTOM2, or CUSTOM3 as options.
  • As optional selector index, or user-defined immediate.
  • 3-bits assignment, with available logic of 0, 1, or x.
  • Assign the bits as x to register the bit for user-defined immediate.
Figure 14. Example Assignments in Hardware Interface Table
Figure 15. Nios V Custom Instruction Manager Examples