Chapter 3 Introduction to MR308
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3.2 Service Call
How does the programmer use the real-time OS in a program?
First, it is necessary to call up a real-time OS function from the program in some way or other. Calling a
real-time OS function is referred to as a service call. Task activation and other processing operations can be
initiated by such a service call (See Figure 3.9).
Key input
Task
Real-time OS Remote control
task
Service call Task switching
Figure 3.9 Service call
This service call is realized by a function call when the application program is written in C language, as shown
below.
sta_tsk(ID_main,3);
Furthermore, if the application program is written in assembly language, it is realized by an assembler macro
call, as shown below.
sta_tsk #ID_main,#3