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Wait For Event.





is an optional condition code.


This is a hint instruction. It is optional whether this instruction is implemented or not. If this instruction is not implemented, it executes as a NOP. The assembler produces a diagnostic message if the instruction executes as a NOP on the target.

If the Event Register is not set, WFE suspends execution until one of the following events occurs:

  • An IRQ interrupt, unless masked by the CPSR I-bit.
  • An FIQ interrupt, unless masked by the CPSR F-bit.
  • An Imprecise Data abort, unless masked by the CPSR A-bit.
  • A Debug Entry request, if Debug is enabled.
  • An Event signaled by another processor using the SEV instruction, or by the current processor using the SEVL instruction.

If the Event Register is set, WFE clears it and returns immediately.

If WFE is implemented, SEV must also be implemented.


This instruction is available in A32 and T32.