1. Chapter 14: 80x86 Port

2. Register Model and Addressing

3. OS_CPU.H

4. OS_CPU.H

5. OS_CPU_C.C OSTaskStkInit OSTaskStkInit_FPE_x86 Hook functions
Borland floating point emulator
Hook functions
OSTaskCreateHook()
OSTaskDelHook()
OSTaskSwHook()
OSTaskIdleHook()
OSTaskStatHook()
OSTimeTickHook()
OSInitHookBegin()

6. OS_CPU_C.C

7. OS_CPU.C – OSStkInit()

8. OS_CPU.C – OSStkInit()
@OSTaskDel
0xFFFF

9. OS_CPU.C – OSStkInit() void OSTaskDelSelf() { OSTaskDel(OS_PRIO_SELF);}

10. OS_CPU_A.ASM
OSStartHighRdy
OSCtxSw
OSIntCtxSw
OSTickISR

11. OSStartHighRdy()

12. LDS, LES, LFS, LGS, and LSS … AX 89 BX (6F2A) 30 … 6F 2A
DS:_OSTCBHighRdy … … … CS
DS(1000)
ES(8930) …
10000

13. OSCtxSw()
The system call which change certain tasks state needs to activate the scheduler and throw an software interrupt. (the macro OS_TASK_SW)
The software trap vectors to the OSCtxSw.

14. OSCtxSw()

15. OSCtxSw()

17. OSIntCtxSw()
OSIntCtxSw is called by OSIntExit to perform a context switch from an ISR.
All registers have been saved onto the interrupted task’s stack
Stack pointer is also saved into the beginning of the ISR has already done that.

18. OSIntCtxSw()

19. OSTickISR() – the Setup Procedure
void main():
Call OSInit
PC_DOSSaveReturn
PC_VecSet //install switch vector at vector 0x80
Create at least one application
Call OSStart
The first task:
Install OSTickISR
(Change the tick rate)

21. Pseudocode

22. OSTickISR()

23. OSTickISR()

24. Using OSTaskStkInit_FPE_x86()

26. ptos
ptos
Size-384
size
pbos
pbos
SS:0000
before
after