T-Kernel Specification (1.B0.02)

90 CHAPTER 4. T-KERNEL/OS FUNCTIONS
tk set flg
tk clr flg
Set Event Flag
Clear Event Flag
[C Language Interface]
ER ercd = tk_set_flg ( ID flgid, UINT setptn ) ;
ER ercd = tk_clr_flg ( ID flgid, UINT clrptn ) ;
[Parameters]
For tk set flg
ID flgid Event flag ID
UINT setptn Bit pattern to be set
For tk clr flg
ID flgid Event flag ID
UINT clrptn Bit pattern to be cleared
[Return Parameters]
ER ercd Error code
[Error Codes]
E OK
E ID
E NOEXS
Normal completion
Invalid ID number (flgid is invalid or cannot be used)
Object does not exist (the event flag designated in flgid does not exist)
[Description]
tk set flg sets the bits indicated in setptn in a one-word event flag designated in flgid. That is,
a logical sum is taken of the values of the event flag designated in flgid and the values indicated in
setptn. tk clr flg clears the bits of the one-word event flag based on the corresponding zero bits of
clrptn. That is, a logical product is taken of the values of the event flag designated in flgid and the
values indicated in clrptn.
After event flag values are changed by tk set flg, if the condition for releasing the wait state of a
task that called tk wai flg is met, the WAIT state of that task is cleared, putting it in RUN state or
READY state (or SUSPEND state if the waiting task was in WAIT-SUSPEND state).
Issuing tk clr flg never results in wait conditions being released for a task waiting for the designated
event flag; that is, dispatching never occurs with tk clr flg.
Nothing will happen to the event flag if all bits of setptn are cleared to 0 with tk set flg or if all bits
of clrptn are set to 1 with tk clr flg. No error will result in either case.
Copyright c○ 2002, 2003 by T-Engine Forum
T-Kernel 1.B0.02