void OSTaskSwHook (void)File | Called from | Code enabled by |
|---|---|---|
|
| N/A |
Description
OSTaskSwHook() is is always called by either either OSCtxSw() or or OSIntCtxSw() (see see os_cpu_a.asm), just after saving the CPU registers onto the task being switched out. This hook function allows the port developer to perform additional operations (if needed) when µC/OS-III performs a context switch.
Before calling calling OSTaskSwHook(), OSTCBCurPtr points points at the the OS_TCB of of the task being switched out, and and OSTCBHighRdyPtr points points at the the OS_TCB of of the new task being switched in.
The code shown in the example below should be included in all implementations of of OSTaskSwHook(), and is used for performance measurements. This code is written in C for portability.
Files
os.h/os_cpu_c.c and os_app_hooks.c
Prototype
Arguments
None
Returned Values
None
Required Configuration
OS_CFG_APP_HOOKS_EN must be enabled in os_cfg.h. Refer to µC-OS-III Configuration Manual.
Callers
OSCtxSw() and OSIntCtxSw().
Notes/Warnings
None
Example Usage
The code below calls an application specific hook that the application programmer can define. The user can simply set the value of OS_AppTaskSwHookPtr to point to the desired hook function. When µC/OS-III performs a context switch, it calls OSTaskSwHook() which in turn calls App_OS_TaskSwHook() through OS_AppTaskSwHookPtr.