T-Kernel Specification (1.B0.02)

4.2. TASK-DEPENDENT SYNCHRONIZATION FUNCTIONS 59
tk sus tsk
Suspend Task
[C Language Interface]
ER ercd = tk_sus_tsk ( ID tskid ) ;
[Parameters]
ID tskid Task ID
[Return Parameters]
ER ercd Error code
[Error Codes]
E OK
E ID
E NOEXS
E OBJ
E CTX
E QOVR
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 the invoking task or for a task in DORMANT state)
A task in RUN state was designated in dispatch disabled state
Queuing or nesting overflow (too many nested requests in suscnt)
[Description]
Puts the task designated in tskid in SUSPEND state and interrupts execution by the task.
SUSPEND state is released by issuing system call tk rsm tsk or tk frsm tsk.
If tk sus tsk is called for a task already in WAIT state, the state goes to a combination of WAIT state
and SUSPEND state (WAIT-SUSPEND state). Thereafter when the task wait release conditions are
met, the task goes to SUSPEND state. If tk rsm tsk is issued for the task in WAIT-SUSPEND state,
the task state reverts to WAIT state.
Since SUSPEND state means task interruption by a system call issued by another task, this system call
cannot be issued for the invoking task. If the invoking task is designated, error code E OBJ is returned.
When this system call is issued from a task-independent portion, if a task in RUN state is designated
while dispatching is disabled, error code E CTX is returned.
If tk sus tsk is issued more than once for the same task, the task is put in SUSPEND state multiple
times. This is called nesting of suspend requests. In this case, the task reverts to its original state only
when tk rsm tsk has been issued for the same number of times as tk sus tsk (suscnt). Accordingly,
nesting of the pair tk sus tsk — tk rsm tsk is possible.
The nesting of suspend requests (issuing tk sus tsk two or more times for the same task) and limits
on nesting count are implementation-dependent.
If tk sus tsk is issued multiple times in a system that does not allow suspend request nesting, or if the
nesting count exceeds the allowed limit, error code E QOVR is returned.
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T-Kernel 1.B0.02