OSTaskReturnHook

Description

This function is called by OS_TaskReturn(). OS_TaskReturn() is called if the user accidentally returns from the task code. In other words, the task should either be implemented as an infinite loop and never return, or the task must call OSTaskDel((OS_TCB *)0, &err) to delete itself to prevent it from exiting.

OSTaskReturnHook() is part of the CPU port code and this function must not be called by the application code. OSTaskReturnHook() is actually used by the µC/OS-III port developer.

Note that after calling OSTaskReturnHook(), OS_TaskReturn() will actually delete the task by calling:

OSTaskDel((OS_TCB *)0,

          &err)

Files

os.h/os_cpu_c.c and os_app_hooks.c

Prototype

void  OSTaskReturnHook (OS_TCB  *p_tcb)

Arguments

p_tcb

is a pointer to the TCB of the task that is not behaving as expected. Note that the OS_TCB is validated by OS_TaskReturn(), and is guaranteed to not be a NULL pointer when OSTaskReturnHook() is called.

Returned Value

None

Required Configuration

OS_CFG_APP_HOOKS_EN must be enabled in os_cfg.h. Refer to µC-OS-III Configuration Manual.

Callers

OS_TaskReturn().

Notes/Warnings

1. Do not call this function from the application.

Example Usage

The code below calls an application-specific hook that the application programmer can define. For this, the user can simply set the value of OS_AppTaskReturnHookPtr to point to the desired hook function as shown in the example. If a task returns and forgets to call OSTaskDel((OS_TCB *)0, &err) then µC/OS-III will call OSTaskReturnHook() which in turns calls App_OS_TaskReturnHook() through OS_AppTaskReturnHookPtr. When called, the application hook is passed the address of the OS_TCB of the task returning.

          void  App_OS_TaskReturnHook (OS_TCB  *p_tcb)                /* os_app_hooks.c         */
          {
              /* Your code goes here! */
          }
           
           
          void App_OS_SetAllHooks (void)                              /* os_app_hooks.c         */
          {
              CPU_SR_ALLOC();
           
              CPU_CRITICAL_ENTER();
              :
              OS_AppTaskReturnHookPtr = App_OS_TaskReturnHook;
              :
              CPU_CRITICAL_EXIT();
          }
           
           
          void  OSTaskReturnHook (OS_TCB *p_tcb)                      /* os_cpu_c.c             */
          {
          #if OS_CFG_APP_HOOKS_EN > 0u
              if (OS_AppTaskReturnHookPtr != (OS_APP_HOOK_TCB)0) {    /* Call application hook  */
                  (*OS_AppTaskReturnHookPtr)(p_tcb);
              }
          #endif
          }