2.9.8. Software interrupt instruction

You can use the Software Interrupt Instruction (SWI) to enter Supervisor mode, usually to request a particular supervisor function. An SWI handler returns by executing the following instruction, irrespective of the processor operating state:

MOVS PC, R14_svc

This action restores the PC and CPSR, and returns to the instruction following the SWI. The SWI handler reads the opcode to extract the SWI function number.

IRQs are automatically disabled when a software interrupt occurs and are automatically re-enabled on return.

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