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CHAPTER 4 TASK MANAGEMENT
User’s Manual U14833EJ2V0UM
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4.14.4 Task exception enabled/disabled states
Tasks have two states related to task exception processing: a task exception enabled state and a task exception
disabled state. In the latter state, task exception processing requests are held pending, and the task exception
processing routine is not activated. The conditions under which the enabled/disabled state changes are summarized
below.
Task exceptions become disabled when:
A task is activated
def_tex is issued and a new exception processing routine is defined
def_tex is issued and an exception processing routine is redefined in the task exception disabled state
(continuance of disabled state)
def_tex is issued and an exception processing routine is canceled
dis_tex is issued
A task exception processing routine is activated
Task exceptions become enabled when:
ena_tex is issued
Processing shifts from a task exception processing routine to a task (except when dis_tex is issued in an
exception processing routine)
def_tex is issued and an exception processing routine is redefined in the task exception enabled state
(continuance of enabled state)
4.14.5 Task exception processing requests
When some kind of event exceptional to a task occurs, (i)ras_tex is issued and a task exception processing
execution request is sent to that task. To issue (i)ras_tex, a 32-bit bit string (TEXPTN type), which is held as the
exception source when the exception processing routine is activated (pending exception source), is specified. If
(i)ras_tex is issued more than once before the task exception processing routine is actually activated, the activation
source is updated with the logical sum of the values specified by the multiple (i)ras_tex service calls.
When a task exception processing routine is activated, the pending exception source is passed as the parameter of
the task exception processing routine, and then cleared to 0. Although it is possible to request exception processing
for the same task by issuing iras_tex from an interrupt servicing routine or cyclic handler activated while the task
exception processing routine is being executed, in this case, the pending exception source will only be updated, and
there will be no effect on the exception source of the task exception processing routine being processed.