return from interrupt การใช้

• Restarting a bytecode ( such as following a return from interrupt ) will re-execute the complete sequence of related ARM instructions.
• The routine ended with the RTI ( ReTurn from Interrupt ) instruction, which restored PC and PSW as of just before the processor granted the interrupt.
• The matching return from interrupt instruction is iret, which restores the flags after returning . " Soft Interrupts " of the type described above are used by some operating systems for system calls, and can also be used in debugging hard interrupt handlers . " Hard interrupts " are triggered by external hardware events, and must preserve all register values as the state of the currently executing program is unknown.