T-Kernel Specification (1.B0.02)

64 CHAPTER 4. T-KERNEL/OS FUNCTIONS
tk sig tev
Signal Task Event
[C Language Interface]
ER ercd = tk_sig_tev ( ID tskid, INT tskevt ) ;
[Parameters]
ID tskid Task ID
INT tskevt Task event number (1 to 8)
[Return Parameters]
ER ercd Error code
[Error Codes]
E OK
E ID
E NOEXS
E OBJ
E PAR
Normal completion
Invalid ID number (tskid is invalid or cannot be used)
Object does not exist (the task designated in tskid does not exist)
Invalid object state (called for a task in DORMANT state)
Parameter error (tskevt is invalid)
[Description]
Sends the task event designated in tskevt to the task designated in tskid. There are eight task event
types stored for each task, designated by numbers 1 to 8.
The task event send count is not saved, only whether the event occurs or not.
The invoking task can be designated by setting tskid = TSK SELF = 0. Note, however, that when a
system call is issued from a task-independent portion and tskid = TSK SELF = 0 is designated, error
code E ID is returned.
[Additional Notes]
The task event function is used for synchronization much like tk slp tsk and tk wup tsk, but differs
from the use of those system calls in the following ways.
• The wakeup request (task event) count is not kept.
• Wakeup requests can be classified by the eight event types.
Using the same event type for synchronization in two or more places in the same task would cause
confusion. Event type allocation should be clearly defined. The task event function is intended for
use in middleware, and as a rule should not be used in ordinary applications. Use of tk slp tsk and
tk wup tsk is recommended for applications.
Copyright c○ 2002, 2003 by T-Engine Forum
T-Kernel 1.B0.02