loc_mtx

Outline

Lock mutex (waiting forever).

C format

 ER      loc_mtx (ID mtxid);

Parameter(s)

I/O	Parameter	Description
I	ID mtxid;	ID number of the mutex to be locked.

Explanation

This service call locks the mutex specified by parameter mtxid.

If the target mutex could not be locked (another task has been locked) when this service call is issued, this service call queues the invoking task to the target mutex wait queue and moves it from the RUNNING state to the WAITING state (mutex wait state).

The WAITING state for a mutex is cancelled in the following cases, and then moved to the READY state.

WAITING State for a Mutex Cancel Operation	Return Value
The locked state of the target mutex was cancelled as a result of issuing unl_mtx.	E_OK
The locked state of the target mutex was cancelled as a result of issuing ext_tsk.	E_OK
The locked state of the target mutex was cancelled as a result of issuing ter_tsk.	E_OK
Forced release from waiting (accept rel_wai while waiting).	E_RLWAI
Forced release from waiting (accept irel_wai while waiting).	E_RLWAI

Note 1 Invoking tasks are queued to the target mutex wait queue in the order defined during configuration (FIFO order or priority order).

Note 2 In the RI850V4, E_ILUSE is returned if this service call is re-issued for the mutex that has been locked by the invoking task (multiple-locking of mutex).

Return value

Macro	Value	Description
E_OK	0	Normal completion.
E_ID	-18	Invalid ID number. - mtxid < 0x0 - mtxid > Maximum ID number
E_CTX	-25	Context error. - This service call was issued from a non-task. - This service call was issued in the CPU locked state. - This service call was issued in the dispatching disabled state.
E_ILUSE	-28	Illegal service call use. - Multiple locking of a mutex.
E_NOEXS	-42	Non-existent object. - Specified mutex is not registered.
E_RLWAI	-49	Forced release from the WAITING state. - Accept rel_wai/irel_wai while waiting.