Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Kernel <strong>Structure</strong> (Cont’d)<br />
• Clock Tick / <strong>OS</strong>TimeTick()<br />
MicroC/<strong>OS</strong>-<strong>II</strong> Clock Tick <br />
Multitasking <strong>OS</strong>Start() Clock Tick<br />
Interrupt .<br />
Clock Tick <br />
‣ <strong>OS</strong>TimeTick(), <strong>OS</strong>TickISR()<br />
void <strong>OS</strong>TickISR(void)<br />
{<br />
Save processor registers;<br />
Call <strong>OS</strong>IntEnter() or increment <strong>OS</strong>IntNesting;<br />
if (<strong>OS</strong>IntNesting == 1) {<br />
<strong>OS</strong>TCBCur-><strong>OS</strong>TCBStkPtr = SP;<br />
}<br />
Post a 'dummy' message (e.g. (void *)1) to the tick mailbox;<br />
}<br />
Call <strong>OS</strong>IntExit();<br />
Restore processor registers;<br />
Execute a return from interrupt instruction;<br />
Embedded System Lab. <strong>II</strong> 32