ISR: Interrupt Service Program

Interrupt service routines (ISR)

 

ISR: interrupt service routine)

The so-called interruption refers to an external event (such as a level change, the occurrence of a pulse edge, or the overflow of the timer count) when the CPU is processing something) the request is processed by the CPU quickly, so the CPU temporarily suspends the current job and forwards it to the processing of the event. After the incident is handled, the interrupted service returns to the place where it was originally suspended to continue its work.

Interrupt is a hardware mechanism that notifies the cpu Of an asynchronous event. Once the interrupt is identified by the system, the CPU stores partial (or all) context values, that is, the values of some (or all) registers, and jumps to a special subroutine, it is called the interrupt service program (ISR ). The interrupted service program processes events and executes task scheduling after processing is completed. The program returns to the task with the highest priority in the ready state to run (for the deprived kernel ).