Nios® V Processor Software Developer Handbook

ID 743810
Date 4/07/2025
Public
Document Table of Contents

9.2.2. CLINT-Vectored Mode

Different from CLINT-Direct, CLINT-Vectored enables the processor to work with a dedicated interrupt vector for every interrupt.
  • Interrupts are handled separately from software exceptions. Each interrupt has its own dedicated vector, tied to its ISRs. Interrupt vectors are calculated from the base address of the vector table and the interrupt cause number.
  • Software exception handling is the same as with the CLINT-Direct. All exceptions are handled by an exception dispatcher residing at a single location - the base address of the vector table.

The CLINT-Vectored is a simple, vectored interrupt controller. Upon receipt of a trap request, the CLINT-Vectored:

  1. Transfers control to the exception vector (for all exceptions) or the individual interrupt vector (specific for each interrupt).
  2. Allows exception (or interrupt) handling code to mask other traps.
The CLINT-Vectored carries out the role of dispatching handler (identifies the trap cause and dispatches the registered ISR). Thus, a simpler trap handling system is implemented under CLINT-Vectored. A total of 16 independent platform interrupt signals are available in CLINT-Vectored.
Table 40.  Supported Traps
Type of Traps List of Traps
Interrupt
  • Machine software interrupt
  • Machine timer interrupt
  • 16 Platform interrupt
Exception
  • Instruction address misaligned
  • Instruction access fault
  • Illegal Instruction
  • Breakpoint
  • Load address misaligned
  • Load access fault
  • Store address misaligned
  • Store access fault
  • Hardware Error