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Completed sweep adding directive and constant prefixes.

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Joel Sherrill
1998-03-27 16:47:53 +00:00
parent 3973e40a54
commit 75e22db0d5
22 changed files with 823 additions and 606 deletions
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doc/user/task.t
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@@ -73,13 +73,12 @@ by the task manager are:
@subsection Task Definition
Many definitions of a task have been proposed in computer
literature. Unfortunately, none of these definitions
encompasses all facets of the concept in a manner which is
operating system independent. Several of the more common
definitions are provided to enable each user to select a
definition which best matches their own experience and
understanding of the task concept:
Many definitions of a task have been proposed in computer literature.
Unfortunately, none of these definitions encompasses all facets of the
concept in a manner which is operating system independent. Several of the
more common definitions are provided to enable each user to select a
definition which best matches their own experience and understanding of the
task concept:
@itemize @bullet
@item a "dispatchable" unit.
@@ -193,35 +192,34 @@ A task's mode is a combination of the following four components:
It is used to modify RTEMS' scheduling process and to alter the
execution environment of the task.
The preemption component allows a task to determine when control
of the processor is relinquished. If preemption is disabled
(@code{@value{RPREFIX}NO_PREEMPT}), the task will retain control of the processor as
long as it is in the executing state -- even if a higher
priority task is made ready. If preemption is enabled (@code{@value{RPREFIX}PREEMPT})
and a higher priority task is made ready, then the processor
will be taken away from the current task immediately and given
to the higher priority task.
The preemption component allows a task to determine when control of the
processor is relinquished. If preemption is disabled
(@code{@value{RPREFIX}NO_PREEMPT}), the task will retain control of the
processor as long as it is in the executing state -- even if a higher
priority task is made ready. If preemption is enabled
(@code{@value{RPREFIX}PREEMPT}) and a higher priority task is made ready,
then the processor will be taken away from the current task immediately and
given to the higher priority task.
The timeslicing component is used by the RTEMS scheduler to
determine how the processor is allocated to tasks of equal
priority. If timeslicing is enabled (@code{@value{RPREFIX}TIMESLICE}), then RTEMS
will limit the amount of time the task can execute before the
processor is allocated to another ready task of equal priority.
The length of the timeslice is application dependent and
specified in the Configuration Table. If timeslicing is
disabled (@code{@value{RPREFIX}NO_TIMESLICE}), then the task will be allowed to
execute until a task of higher priority is made ready. If
@code{@value{RPREFIX}NO_PREEMPT} is selected, then the timeslicing component is
ignored by the scheduler.
The timeslicing component is used by the RTEMS scheduler to determine how
the processor is allocated to tasks of equal priority. If timeslicing is
enabled (@code{@value{RPREFIX}TIMESLICE}), then RTEMS will limit the amount
of time the task can execute before the processor is allocated to another
ready task of equal priority. The length of the timeslice is application
dependent and specified in the Configuration Table. If timeslicing is
disabled (@code{@value{RPREFIX}NO_TIMESLICE}), then the task will be
allowed to execute until a task of higher priority is made ready. If
@code{@value{RPREFIX}NO_PREEMPT} is selected, then the timeslicing
component is ignored by the scheduler.
The asynchronous signal processing component is used to
determine when received signals are to be processed by the task.
If signal processing is enabled (@code{@value{RPREFIX}ASR}), then signals sent to the
task will be processed the next time the task executes. If
signal processing is disabled (@code{@value{RPREFIX}NO_ASR}), then all signals
received by the task will remain posted until signal processing
is enabled. This component affects only tasks which have
established a routine to process asynchronous signals.
The asynchronous signal processing component is used to determine when
received signals are to be processed by the task.
If signal processing is enabled (@code{@value{RPREFIX}ASR}), then signals
sent to the task will be processed the next time the task executes. If
signal processing is disabled (@code{@value{RPREFIX}NO_ASR}), then all
signals received by the task will remain posted until signal processing is
enabled. This component affects only tasks which have established a
routine to process asynchronous signals.
The interrupt level component is used to determine which
interrupts will be enabled when the task is executing.
@@ -274,56 +272,54 @@ single argument as an index into an array of parameter blocks.
@end ifinfo
@subsection Floating Point Considerations
Creating a task with the @code{@value{RPREFIX}FLOATING_POINT} flag results in
additional memory being allocated for the TCB to store the state
of the numeric coprocessor during task switches. This
additional memory is @b{NOT} allocated for @code{@value{RPREFIX}NO_FLOATING_POINT} tasks.
Saving and restoring the context of a @code{@value{RPREFIX}FLOATING_POINT} task takes
longer than that of a @code{@value{RPREFIX}NO_FLOATING_POINT} task because of the
relatively large amount of time required for the numeric
coprocessor to save or restore its computational state.
Creating a task with the @code{@value{RPREFIX}FLOATING_POINT} flag results
in additional memory being allocated for the TCB to store the state of the
numeric coprocessor during task switches. This additional memory is
@b{NOT} allocated for @code{@value{RPREFIX}NO_FLOATING_POINT} tasks. Saving
and restoring the context of a @code{@value{RPREFIX}FLOATING_POINT} task
takes longer than that of a @code{@value{RPREFIX}NO_FLOATING_POINT} task
because of the relatively large amount of time required for the numeric
coprocessor to save or restore its computational state.
Since RTEMS was designed specifically for embedded military
applications which are floating point intensive, the executive
is optimized to avoid unnecessarily saving and restoring the
state of the numeric coprocessor. The state of the numeric
coprocessor is only saved when a @code{@value{RPREFIX}FLOATING_POINT} task is
dispatched and that task was not the last task to utilize the
coprocessor. In a system with only one @code{@value{RPREFIX}FLOATING_POINT} task, the
state of the numeric coprocessor will never be saved or
restored.
Since RTEMS was designed specifically for embedded military applications
which are floating point intensive, the executive is optimized to avoid
unnecessarily saving and restoring the state of the numeric coprocessor.
The state of the numeric coprocessor is only saved when a
@code{@value{RPREFIX}FLOATING_POINT} task is dispatched and that task was
not the last task to utilize the coprocessor. In a system with only one
@code{@value{RPREFIX}FLOATING_POINT} task, the state of the numeric
coprocessor will never be saved or restored.
Although the overhead imposed by @code{@value{RPREFIX}FLOATING_POINT} tasks is
minimal, some applications may wish to completely avoid the
overhead associated with @code{@value{RPREFIX}FLOATING_POINT} tasks and still utilize
a numeric coprocessor. By preventing a task from being
preempted while performing a sequence of floating point
operations, a @code{@value{RPREFIX}NO_FLOATING_POINT} task can utilize the numeric
coprocessor without incurring the overhead of a @code{@value{RPREFIX}FLOATING_POINT}
context switch. This approach also avoids the allocation of a
floating point context area. However, if this approach is taken
by the application designer, NO tasks should be created as
@code{@value{RPREFIX}FLOATING_POINT} tasks. Otherwise, the floating point context
will not be correctly maintained because RTEMS assumes that the
state of the numeric coprocessor will not be altered by
@code{@value{RPREFIX}NO_FLOATING_POINT} tasks.
Although the overhead imposed by @code{@value{RPREFIX}FLOATING_POINT} tasks
is minimal, some applications may wish to completely avoid the overhead
associated with @code{@value{RPREFIX}FLOATING_POINT} tasks and still
utilize a numeric coprocessor. By preventing a task from being preempted
while performing a sequence of floating point operations, a
@code{@value{RPREFIX}NO_FLOATING_POINT} task can utilize the numeric
coprocessor without incurring the overhead of a
@code{@value{RPREFIX}FLOATING_POINT} context switch. This approach also
avoids the allocation of a floating point context area. However, if this
approach is taken by the application designer, NO tasks should be created
as @code{@value{RPREFIX}FLOATING_POINT} tasks. Otherwise, the floating
point context will not be correctly maintained because RTEMS assumes that
the state of the numeric coprocessor will not be altered by
@code{@value{RPREFIX}NO_FLOATING_POINT} tasks.
If the supported processor type does not have hardware floating
capabilities or a standard numeric coprocessor, RTEMS will not
provide built-in support for hardware floating point on that
processor. In this case, all tasks are considered
@code{@value{RPREFIX}NO_FLOATING_POINT} whether created as @code{@value{RPREFIX}FLOATING_POINT} or
@code{@value{RPREFIX}NO_FLOATING_POINT} tasks. A floating point emulation software
library must be utilized for floating point operations.
capabilities or a standard numeric coprocessor, RTEMS will not provide
built-in support for hardware floating point on that processor. In this
case, all tasks are considered @code{@value{RPREFIX}NO_FLOATING_POINT}
whether created as @code{@value{RPREFIX}FLOATING_POINT} or
@code{@value{RPREFIX}NO_FLOATING_POINT} tasks. A floating point emulation
software library must be utilized for floating point operations.
On some processors, it is possible to disable the floating point
unit dynamically. If this capability is supported by the target
processor, then RTEMS will utilize this capability to enable the
floating point unit only for tasks which are created with the
@code{@value{RPREFIX}FLOATING_POINT} attribute. The consequence of a
@code{@value{RPREFIX}NO_FLOATING_POINT} task attempting to access the floating point
unit is CPU dependent but will i general result in an exception
condition.
On some processors, it is possible to disable the floating point unit
dynamically. If this capability is supported by the target processor, then
RTEMS will utilize this capability to enable the floating point unit only
for tasks which are created with the @code{@value{RPREFIX}FLOATING_POINT}
attribute. The consequence of a @code{@value{RPREFIX}NO_FLOATING_POINT}
task attempting to access the floating point unit is CPU dependent but will
generally result in an exception condition.
@ifinfo
@node Building a Task's Attribute Set, Building a Mode and Mask, Floating Point Considerations, Task Manager Background
@@ -438,57 +434,53 @@ listed below:
<TR><TD ALIGN=center><STRONG>Mode Constant</STRONG></TD>
<TD ALIGN=center><STRONG>Mask Constant</STRONG></TD>
<TD ALIGN=center><STRONG>Description</STRONG></TD></TR>
<TR><TD ALIGN=center>PREEMPT</TD>
<TD ALIGN=center>PREEMPT_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}PREEMPT</TD>
<TD ALIGN=center>@value{RPREFIX}PREEMPT_MASK</TD>
<TD ALIGN=center>enables preemption</TD></TR>
<TR><TD ALIGN=center>NO_PREEMPT</TD>
<TD ALIGN=center>PREEMPT_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}NO_PREEMPT</TD>
<TD ALIGN=center>@value{RPREFIX}PREEMPT_MASK</TD>
<TD ALIGN=center>disables preemption</TD></TR>
<TR><TD ALIGN=center>NO_TIMESLICE</TD>
<TD ALIGN=center>TIMESLICE_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}NO_TIMESLICE</TD>
<TD ALIGN=center>@value{RPREFIX}TIMESLICE_MASK</TD>
<TD ALIGN=center>disables timeslicing</TD></TR>
<TR><TD ALIGN=center>TIMESLICE</TD>
<TD ALIGN=center>TIMESLICE_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}TIMESLICE</TD>
<TD ALIGN=center>@value{RPREFIX}TIMESLICE_MASK</TD>
<TD ALIGN=center>enables timeslicing</TD></TR>
<TR><TD ALIGN=center>ASR</TD>
<TD ALIGN=center>ASR_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}ASR</TD>
<TD ALIGN=center>@value{RPREFIX}ASR_MASK</TD>
<TD ALIGN=center>enables ASR processing</TD></TR>
<TR><TD ALIGN=center>NO_ASR</TD>
<TD ALIGN=center>ASR_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}NO_ASR</TD>
<TD ALIGN=center>@value{RPREFIX}ASR_MASK</TD>
<TD ALIGN=center>disables ASR processing</TD></TR>
<TR><TD ALIGN=center>INTERRUPT_LEVEL(0)</TD>
<TD ALIGN=center>INTERRUPT_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}INTERRUPT_LEVEL(0)</TD>
<TD ALIGN=center>@value{RPREFIX}INTERRUPT_MASK</TD>
<TD ALIGN=center>enables all interrupts</TD></TR>
<TR><TD ALIGN=center>INTERRUPT_LEVEL(n)</TD>
<TD ALIGN=center>INTERRUPT_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}INTERRUPT_LEVEL(n)</TD>
<TD ALIGN=center>@value{RPREFIX}INTERRUPT_MASK</TD>
<TD ALIGN=center>sets interrupts level n</TD></TR>
</TABLE>
</CENTER>
@end html
@end ifset
Mode values are specifically designed to be mutually exclusive, therefore
bitwise OR and addition operations are equivalent as long as each mode
appears exactly once in the component list. A mode component listed as a
default is not required to appear in the mode component list, although it
is a good programming practice to specify default components. If all
defaults are desired, the mode @code{@value{RPREFIX}DEFAULT_MODES} and the
mask @code{@value{RPREFIX}ALL_MODE_MASKS} should be used.
Mode values are specifically designed to be mutually exclusive,
therefore bitwise OR and addition operations are equivalent as
long as each mode appears exactly once in the component list. A
mode component listed as a default is not required to appear in
the mode component list, although it is a good programming
practice to specify default components. If all defaults are
desired, the mode @code{@value{RPREFIX}DEFAULT_MODES} and the mask @code{@value{RPREFIX}ALL_MODE_MASKS}
should be used.
The following example demonstrates the mode and mask parameters
used with the task_mode directive to place a task at interrupt
level 3 and make it non-preemptible. The mode should be set to
@code{@value{RPREFIX}INTERRUPT_LEVEL(3)
@value{OR} @value{RPREFIX}NO_PREEMPT} to indicate the desired
preemption mode and interrupt level, while the mask parameter
should be set to
@code{@value{RPREFIX}INTERRUPT_MASK @value{OR} @value{RPREFIX}NO_PREEMPT_MASK}
to indicate that the calling task's interrupt level and preemption mode are
being altered.
The following example demonstrates the mode and mask parameters used with
the @code{@value{DIRPREFIX}task_mode}
directive to place a task at interrupt level 3 and make it
non-preemptible. The mode should be set to
@code{@value{RPREFIX}INTERRUPT_LEVEL(3) @value{OR}
@value{RPREFIX}NO_PREEMPT} to indicate the desired preemption mode and
interrupt level, while the mask parameter should be set to
@code{@value{RPREFIX}INTERRUPT_MASK @value{OR}
@value{RPREFIX}NO_PREEMPT_MASK} to indicate that the calling task's
interrupt level and preemption mode are being altered.
@ifinfo
@node Task Manager Operations, Creating Tasks, Building a Mode and Mask, Task Manager
@@ -515,7 +507,8 @@ being altered.
@end ifinfo
@subsection Creating Tasks
The task_create directive creates a task by allocating a task
The @code{@value{DIRPREFIX}task_create}
directive creates a task by allocating a task
control block, assigning the task a user-specified name,
allocating it a stack and floating point context area, setting a
user-specified initial priority, setting a user-specified
@@ -531,9 +524,11 @@ execute in the most privileged mode of the processor.
When a task is created, RTEMS generates a unique task ID and
assigns it to the created task until it is deleted. The task ID
may be obtained by either of two methods. First, as the result
of an invocation of the task_create directive, the task ID is
of an invocation of the @code{@value{DIRPREFIX}task_create}
directive, the task ID is
stored in a user provided location. Second, the task ID may be
obtained later using the task_ident directive. The task ID is
obtained later using the @code{@value{DIRPREFIX}task_ident}
directive. The task ID is
used by other directives to manipulate this task.
@ifinfo
@@ -541,14 +536,16 @@ used by other directives to manipulate this task.
@end ifinfo
@subsection Starting and Restarting Tasks
The task_start directive is used to place a dormant task in the
The @code{@value{DIRPREFIX}task_start}
directive is used to place a dormant task in the
ready state. This enables the task to compete, based on its
current priority, for the processor and other system resources.
Any actions, such as suspension or change of priority, performed
on a task prior to starting it are nullified when the task is
started.
With the task_start directive the user specifies the task's
With the @code{@value{DIRPREFIX}task_start}
directive the user specifies the task's
starting address and argument. The argument is used to
communicate some startup information to the task. As part of
this directive, RTEMS initializes the task's stack based upon
@@ -556,7 +553,8 @@ the task's initial execution mode and start address. The
starting argument is passed to the task in accordance with the
target processor's calling convention.
The task_restart directive restarts a task at its initial
The @code{@value{DIRPREFIX}task_restart}
directive restarts a task at its initial
starting address with its original priority and execution mode,
but with a possibly different argument. The new argument may be
used to distinguish between the original invocation of the task
@@ -573,13 +571,16 @@ restarted). All restarted tasks are placed in the ready state.
@end ifinfo
@subsection Suspending and Resuming Tasks
The task_suspend directive is used to place either the caller or
The @code{@value{DIRPREFIX}task_suspend}
directive is used to place either the caller or
another task into a suspended state. The task remains suspended
until a task_resume directive is issued. This implies that a
until a @code{@value{DIRPREFIX}task_resume}
directive is issued. This implies that a
task may be suspended as well as blocked waiting either to
acquire a resource or for the expiration of a timer.
The task_resume directive is used to remove another task from
The @code{@value{DIRPREFIX}task_resume}
directive is used to remove another task from
the suspended state. If the task is not also blocked, resuming
it will place it in the ready state, allowing it to once again
compete for the processor and resources. If the task was
@@ -594,15 +595,17 @@ task which is not suspended is considered an error.
@end ifinfo
@subsection Delaying the Currently Executing Task
The task_wake_after directive creates a sleep timer which allows
a task to go to sleep for a specified interval. The task is
blocked until the delay interval has elapsed, at which time the
task is unblocked. A task calling the task_wake_after directive
with a delay interval of @code{@value{RPREFIX}YIELD_PROCESSOR} ticks will yield the
processor to any other ready task of equal or greater priority
and remain ready to execute.
The @code{@value{DIRPREFIX}task_wake_after} directive creates a sleep timer
which allows a task to go to sleep for a specified interval. The task is
blocked until the delay interval has elapsed, at which time the task is
unblocked. A task calling the @code{@value{DIRPREFIX}task_wake_after}
directive with a delay
interval of @code{@value{RPREFIX}YIELD_PROCESSOR} ticks will yield the
processor to any other ready task of equal or greater priority and remain
ready to execute.
The task_wake_when directive creates a sleep timer which allows
The @code{@value{DIRPREFIX}task_wake_when}
directive creates a sleep timer which allows
a task to go to sleep until a specified date and time. The
calling task is blocked until the specified date and time has
occurred, at which time the task is unblocked.
@@ -612,15 +615,18 @@ occurred, at which time the task is unblocked.
@end ifinfo
@subsection Changing Task Priority
The task_set_priority directive is used to obtain or change the
The @code{@value{DIRPREFIX}task_set_priority}
directive is used to obtain or change the
current priority of either the calling task or another task. If
the new priority requested is CURRENT_PRIORITY or the task's
the new priority requested is
@code{@value{RPREFIX}CURRENT_PRIORITY} or the task's
actual priority, then the current priority will be returned and
the task's priority will remain unchanged. If the task's
priority is altered, then the task will be scheduled according
to its new priority.
The task_restart directive resets the priority of a task to its
The @code{@value{DIRPREFIX}task_restart}
directive resets the priority of a task to its
original value.
@ifinfo
@@ -628,12 +634,14 @@ original value.
@end ifinfo
@subsection Changing Task Mode
The task_mode directive is used to obtain or change the current
The @code{@value{DIRPREFIX}task_mode}
directive is used to obtain or change the current
execution mode of the calling task. A task's execution mode is
used to enable preemption, timeslicing, ASR processing, and to
set the task's interrupt level.
The task_restart directive resets the mode of a task to its
The @code{@value{DIRPREFIX}task_restart}
directive resets the mode of a task to its
original value.
@ifinfo
@@ -643,11 +651,15 @@ original value.
RTEMS provides sixteen notepad locations for each task. Each
notepad location may contain a note consisting of four bytes of
information. RTEMS provides two directives, task_set_note and
task_get_note, that enable a user to access and change the
notepad locations. The task_set_note directive enables the user
information. RTEMS provides two directives,
@code{@value{DIRPREFIX}task_set_note} and
@code{@value{DIRPREFIX}task_get_note}, that enable a user
to access and change the
notepad locations. The @code{@value{DIRPREFIX}task_set_note}
directive enables the user
to set a task's notepad entry to a specified note. The
task_get_note directive allows the user to obtain the note
@code{@value{DIRPREFIX}task_get_note}
directive allows the user to obtain the note
contained in any one of the sixteen notepads of a specified task.
@ifinfo
@@ -655,7 +667,8 @@ contained in any one of the sixteen notepads of a specified task.
@end ifinfo
@subsection Task Deletion
RTEMS provides the task_delete directive to allow a task to
RTEMS provides the @code{@value{DIRPREFIX}task_delete}
directive to allow a task to
delete itself or any other task. This directive removes all
RTEMS references to the task, frees the task's control block,
removes it from resource wait queues, and deallocates its stack
@@ -665,8 +678,10 @@ references to either of them is invalid. In fact, RTEMS may
reuse the task ID for another task which is created later in the
application.
Unexpired delay timers (i.e. those used by task_wake_after and
task_wake_when) and timeout timers associated with the task are
Unexpired delay timers (i.e. those used by
@code{@value{DIRPREFIX}task_wake_after} and
@code{@value{DIRPREFIX}task_wake_when}) and
timeout timers associated with the task are
automatically deleted, however, other resources dynamically
allocated by the task are NOT automatically returned to RTEMS.
Therefore, before a task is deleted, all of its dynamically
@@ -757,15 +772,17 @@ This directive creates a task which resides on the local node.
It allocates and initializes a TCB, a stack, and an optional
floating point context area. The mode parameter contains values
which sets the task's initial execution mode. The
@code{@value{RPREFIX}FLOATING_POINT} attribute should be specified if the created task
@code{@value{RPREFIX}FLOATING_POINT} attribute should be
specified if the created task
is to use a numeric coprocessor. For performance reasons, it is
recommended that tasks not using the numeric coprocessor should
specify the @code{@value{RPREFIX}NO_FLOATING_POINT} attribute. If the GLOBAL
specify the @code{@value{RPREFIX}NO_FLOATING_POINT} attribute.
If the @code{@value{RPREFIX}GLOBAL}
attribute is specified, the task can be accessed from remote
nodes. The task id, returned in id, is used in other task
related directives to access the task. When created, a task is
placed in the dormant state and can only be made ready to
execute using the directive task_start.
execute using the directive @code{@value{DIRPREFIX}task_start}.
@subheading NOTES:
This directive will not cause the calling task to be preempted.
@@ -776,8 +793,10 @@ RTEMS supports a maximum of 256 interrupt levels which are
mapped onto the interrupt levels actually supported by the
target processor.
The requested stack size should be at least @code{@value{RPREFIX}MINIMUM_STACK_SIZE}
bytes. The value of @code{@value{RPREFIX}MINIMUM_STACK_SIZE} is processor dependent.
The requested stack size should be at least
@code{@value{RPREFIX}MINIMUM_STACK_SIZE}
bytes. The value of @code{@value{RPREFIX}MINIMUM_STACK_SIZE}
is processor dependent.
Application developers should consider the stack usage of the
device drivers when calculating the stack size required for
tasks which utilize the driver.
@@ -922,7 +941,7 @@ enabled and the task being started has a higher priority.
Any actions performed on a dormant task such as suspension or
change of priority are nullified when the task is initiated via
the task_start directive.
the @code{@value{DIRPREFIX}task_start} directive.
@page
@@ -968,9 +987,12 @@ dormant state.
The task's starting argument is contained in argument. This
argument can be a single value or an index into an array of
parameter blocks. This new argument may be used to distinguish
between the initial task_start of the task and any ensuing calls
to task_restart of the task. This can be beneficial in deleting
a task. Instead of deleting a task using the task_delete
between the initial @code{@value{DIRPREFIX}task_start}
of the task and any ensuing calls
to @code{@value{DIRPREFIX}task_restart}
of the task. This can be beneficial in deleting
a task. Instead of deleting a task using
the @code{@value{DIRPREFIX}task_delete}
directive, a task can delete another task by restarting that
task, and allowing that task to release resources back to RTEMS
and then delete itself.
@@ -983,7 +1005,7 @@ The calling task will be preempted if its preemption mode is
enabled and the task being restarted has a higher priority.
The task must reside on the local node, even if the task was
created with the GLOBAL option.
created with the @code{@value{RPREFIX}GLOBAL} option.
@page
@@ -1042,7 +1064,7 @@ to every node in the system for deletion from the local copy of
the global object table.
The task must reside on the local node, even if the task was
created with the GLOBAL option.
created with the @code{@value{RPREFIX}GLOBAL} option.
@page
@@ -1079,7 +1101,8 @@ This directive suspends the task specified by id from further
execution by placing it in the suspended state. This state is
additive to any other blocked state that the task may already be
in. The task will not execute again until another task issues
the task_resume directive for this task and any blocked state
the @code{@value{DIRPREFIX}task_resume}
directive for this task and any blocked state
has been removed.
@subheading NOTES:
@@ -1092,7 +1115,7 @@ will generate a request to the remote node to suspend the
specified task.
If the task specified by id is already suspended, then the
ALREADY_SUSPENDED status code is returned.
@code{@value{RPREFIX}ALREADY_SUSPENDED} status code is returned.
@page
@@ -1140,7 +1163,7 @@ will generate a request to the remote node to resume the
specified task.
If the task specified by id is not suspended, then the
INCORRECT_STATE status code is returned.
@code{@value{RPREFIX}INCORRECT_STATE} status code is returned.
@page
@@ -1178,10 +1201,12 @@ procedure Task_Set_Priority (
@subheading DESCRIPTION:
This directive manipulates the priority of the task specified by
id. An id of @code{@value{RPREFIX}SELF} is used to indicate the calling task. When
new_priority is not equal to CURRENT_PRIORITY, the specified
id. An id of @code{@value{RPREFIX}SELF} is used to indicate
the calling task. When new_priority is not equal to
@code{@value{RPREFIX}CURRENT_PRIORITY}, the specified
task's previous priority is returned in old_priority. When
new_priority is CURRENT_PRIORITY, the specified task's current
new_priority is @code{@value{RPREFIX}CURRENT_PRIORITY},
the specified task's current
priority is returned in old_priority. Valid priorities range
from a high of 1 to a low of 255.
@@ -1252,25 +1277,41 @@ a higher priority task is ready to run.
Enabling timeslicing has no effect if preemption is enabled.
A task can obtain its current execution mode, without modifying
it, by calling this directive with a mask value of @code{@value{RPREFIX}CURRENT_MODE}.
it, by calling this directive with a mask value of
@code{@value{RPREFIX}CURRENT_MODE}.
To temporarily disable the processing of a valid ASR, a task
should call this directive with the NO_ASR indicator specified
in mode.
should call this directive with the @code{@value{RPREFIX}NO_ASR}
indicator specified in mode.
The set of task mode constants and each mode's corresponding
mask constant is provided in the following table:
@ifset use-ascii
@itemize @bullet
@item PREEMPT is masked by PREEMPT_MASK and enables preemption
@item NO_PREEMPT is masked by PREEMPT_MASK and disables preemption
@item NO_TIMESLICE is masked by TIMESLICE_MASK and disables timeslicing
@item TIMESLICE is masked by TIMESLICE_MASK and enables timeslicing
@item ASR is masked by ASR_MASK and enables ASR processing
@item NO_ASR is masked by ASR_MASK and disables ASR processing
@item INTERRUPT_LEVEL(0) is masked by INTERRUPT_MASK and enables all interrupts
@item INTERRUPT_LEVEL(n) is masked by INTERRUPT_MASK and sets interrupts level n
@item @code{@value{RPREFIX}PREEMPT} is masked by
@code{@value{RPREFIX}PREEMPT_MASK} and enables preemption
@item @code{@value{RPREFIX}NO_PREEMPT} is masked by
@code{@value{RPREFIX}PREEMPT_MASK} and disables preemption
@item @code{@value{RPREFIX}NO_TIMESLICE} is masked by
@code{@value{RPREFIX}TIMESLICE_MASK} and disables timeslicing
@item @code{@value{RPREFIX}TIMESLICE} is masked by
@code{@value{RPREFIX}TIMESLICE_MASK} and enables timeslicing
@item @code{@value{RPREFIX}ASR} is masked by
@code{@value{RPREFIX}ASR_MASK} and enables ASR processing
@item @code{@value{RPREFIX}NO_ASR} is masked by
@code{@value{RPREFIX}ASR_MASK} and disables ASR processing
@item @code{@value{RPREFIX}INTERRUPT_LEVEL(0)} is masked by
@code{@value{RPREFIX}INTERRUPT_MASK} and enables all interrupts
@item @code{@value{RPREFIX}INTERRUPT_LEVEL(n)} is masked by
@code{@value{RPREFIX}INTERRUPT_MASK} and sets interrupts level n
@end itemize
@end ifset
@@ -1279,14 +1320,29 @@ mask constant is provided in the following table:
@sp 1
@c this is temporary
@itemize @bullet
@item PREEMPT is masked by PREEMPT_MASK and enables preemption
@item NO_PREEMPT is masked by PREEMPT_MASK and disables preemption
@item NO_TIMESLICE is masked by TIMESLICE_MASK and disables timeslicing
@item TIMESLICE is masked by TIMESLICE_MASK and enables timeslicing
@item ASR is masked by ASR_MASK and enables ASR processing
@item NO_ASR is masked by ASR_MASK and disables ASR processing
@item INTERRUPT_LEVEL(0) is masked by INTERRUPT_MASK and enables all interrupts
@item INTERRUPT_LEVEL(n) is masked by INTERRUPT_MASK and sets interrupts level n
@item @code{@value{RPREFIX}PREEMPT} is masked by
@code{@value{RPREFIX}PREEMPT_MASK} and enables preemption
@item @code{@value{RPREFIX}NO_PREEMPT} is masked by
@code{@value{RPREFIX}PREEMPT_MASK} and disables preemption
@item @code{@value{RPREFIX}NO_TIMESLICE} is masked by
@code{@value{RPREFIX}TIMESLICE_MASK} and disables timeslicing
@item @code{@value{RPREFIX}TIMESLICE} is masked by
@code{@value{RPREFIX}TIMESLICE_MASK} and enables timeslicing
@item @code{@value{RPREFIX}ASR} is masked by
@code{@value{RPREFIX}ASR_MASK} and enables ASR processing
@item @code{@value{RPREFIX}NO_ASR} is masked by
@code{@value{RPREFIX}ASR_MASK} and disables ASR processing
@item @code{@value{RPREFIX}INTERRUPT_LEVEL(0)} is masked by
@code{@value{RPREFIX}INTERRUPT_MASK} and enables all interrupts
@item @code{@value{RPREFIX}INTERRUPT_LEVEL(n)} is masked by
@code{@value{RPREFIX}INTERRUPT_MASK} and sets interrupts level n
@end itemize
@@ -1301,29 +1357,29 @@ mask constant is provided in the following table:
<TR><TD ALIGN=center><STRONG>Mode Constant</STRONG></TD>
<TD ALIGN=center><STRONG>Mask Constant</STRONG></TD>
<TD ALIGN=center><STRONG>Description</STRONG></TD></TR>
<TR><TD ALIGN=center>PREEMPT</TD>
<TD ALIGN=center>PREEMPT_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}PREEMPT</TD>
<TD ALIGN=center>@value{RPREFIX}PREEMPT_MASK</TD>
<TD ALIGN=center>enables preemption</TD></TR>
<TR><TD ALIGN=center>NO_PREEMPT</TD>
<TD ALIGN=center>PREEMPT_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}NO_PREEMPT</TD>
<TD ALIGN=center>@value{RPREFIX}PREEMPT_MASK</TD>
<TD ALIGN=center>disables preemption</TD></TR>
<TR><TD ALIGN=center>NO_TIMESLICE</TD>
<TD ALIGN=center>TIMESLICE_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}NO_TIMESLICE</TD>
<TD ALIGN=center>@value{RPREFIX}TIMESLICE_MASK</TD>
<TD ALIGN=center>disables timeslicing</TD></TR>
<TR><TD ALIGN=center>TIMESLICE</TD>
<TD ALIGN=center>TIMESLICE_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}TIMESLICE</TD>
<TD ALIGN=center>@value{RPREFIX}TIMESLICE_MASK</TD>
<TD ALIGN=center>enables timeslicing</TD></TR>
<TR><TD ALIGN=center>ASR</TD>
<TD ALIGN=center>ASR_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}ASR</TD>
<TD ALIGN=center>@value{RPREFIX}ASR_MASK</TD>
<TD ALIGN=center>enables ASR processing</TD></TR>
<TR><TD ALIGN=center>NO_ASR</TD>
<TD ALIGN=center>ASR_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}NO_ASR</TD>
<TD ALIGN=center>@value{RPREFIX}ASR_MASK</TD>
<TD ALIGN=center>disables ASR processing</TD></TR>
<TR><TD ALIGN=center>INTERRUPT_LEVEL(0)</TD>
<TD ALIGN=center>INTERRUPT_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}INTERRUPT_LEVEL(0)</TD>
<TD ALIGN=center>@value{RPREFIX}INTERRUPT_MASK</TD>
<TD ALIGN=center>enables all interrupts</TD></TR>
<TR><TD ALIGN=center>INTERRUPT_LEVEL(n)</TD>
<TD ALIGN=center>INTERRUPT_MASK</TD>
<TR><TD ALIGN=center>@value{RPREFIX}INTERRUPT_LEVEL(n)</TD>
<TD ALIGN=center>@value{RPREFIX}INTERRUPT_MASK</TD>
<TD ALIGN=center>sets interrupts level n</TD></TR>
</TABLE>
</CENTER>
@@ -1371,7 +1427,8 @@ location of the task specified by id.
@subheading NOTES:
This directive will not cause the running task to be preempted.
If id is set to @code{@value{RPREFIX}SELF}, the calling task accesses its own notepad.
If id is set to @code{@value{RPREFIX}SELF},
the calling task accesses its own notepad.
@c This version of the paragraph avoids the overfull hbox error.
@c The constants NOTEPAD_0 through NOTEPAD_15 can be used to access the
@@ -1423,8 +1480,8 @@ This directive sets the notepad entry for the task specified by
id to the value note.
@subheading NOTES:
If id is set to @code{@value{RPREFIX}SELF}, the calling task accesses its own notepad
locations.
If id is set to @code{@value{RPREFIX}SELF}, the calling
task accesses its own notepad locations.
This directive will not cause the running task to be preempted.
@@ -1470,12 +1527,13 @@ procedure Task_Wake_After (
@subheading DESCRIPTION:
This directive blocks the calling task for the specified number
of system clock ticks. When the requested interval has elapsed,
the task is made ready. The clock_tick directive automatically
updates the delay period.
the task is made ready. The @code{@value{DIRPREFIX}clock_tick}
directive automatically updates the delay period.
@subheading NOTES:
Setting the system date and time with the clock_set directive
has no effect on a task_wake_after blocked task.
Setting the system date and time with the
@code{@value{DIRPREFIX}clock_set} directive
has no effect on a @code{@value{DIRPREFIX}task_wake_after} blocked task.
A task may give up the processor and remain in the ready state
by specifying a value of @code{@value{RPREFIX}YIELD_PROCESSOR} in ticks.