1287_ Implementation analysis of prvtaskistasksuspended() interface in FreeRTOS

All learning summary ： GreyZhang/g_FreeRTOS: learning notes about FreeRTOS. (github.com)

Take a look this time prvTaskIsTaskSuspended() The interface of , This interface is used to judge a task Whether it is in a suspended state . Usually , The interface implementation of this judgment class is simpler . Similar to the previous implementation of obtaining task priority , So it is with . Because its function is to query rather than modify , Yes OS The overall operating environment does not have much impact .

Many interfaces are being implemented , Task handle if NULL The default is to process the current task . But in this interface, this explanation is meaningless , As long as the task is executing the query action, it means that the current task is not suspended .

This is the main part of the interface implementation , Made a simple note . Query implementation is relatively simple , First, judge whether the task is in the linked list of suspended tasks . If not , There is no need to query directly , Definitely not a suspended task . So is it necessarily a suspended task ？ In fact, it is not .

The query implemented by this interface , In fact, it realizes whether the suspended state of task non execution is triggered by the suspended action . If the suspension is caused by blocking , Nor should it return as a pending state . thus , It is not only the attribution state of a linked list element that is judged , We have to see whether the event status is valid , Because the event state represents that the task enters the suspended linked list because it is not executed due to non suspended actions .

With the rules above , The determined result can be returned as the return result .