Nios® V Processor Software Developer Handbook

ID 743810
Date 4/07/2025
Public

Visible to Intel only — GUID: kxf1733359748096

Ixiasoft

Document Table of Contents

9.2.1. CLINT-Direct Mode

All traps (both exceptions and interrupts) are dispatched through a single top-level trap handling code. In other words, all traps are handled by code residing at a single location - the exception vector.
The CLINT-Direct is a simple, non-vectored interrupt controller. Upon receipt of a trap request, the CLINT-Direct :
  1. Transfers control to exception vector.
  2. Identifies which IRQ is currently asserted.
  3. Allows trap handling code to mask other traps.
To complement CLINT-Direct, the trap handling code identifies the trap cause and dispatches the registered ISR. CLINT-Direct has 16 independent platform interrupt signals. These interrupt signals allow software to prioritize interrupts, although the interrupt signals themselves have no inherent priority from a hardware perspective
Table 38.  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