Description
OSTaskSwHook() is always called by either OSCtxSw() or OSIntCtxSw() (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 OSTaskSwHook(), OSTCBCurPtr points at the OS_TCB of the task being switched out, and OSTCBHighRdyPtr points at the OS_TCB of the new task being switched in.
The code shown in the example below should be included in all implementations 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.