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Diffstat (limited to '')
| -rw-r--r-- | doc/user/sem.t | 103 |
1 files changed, 2 insertions, 101 deletions
diff --git a/doc/user/sem.t b/doc/user/sem.t index 9697da82e4..8f63cdc727 100644 --- a/doc/user/sem.t +++ b/doc/user/sem.t @@ -6,22 +6,8 @@ @c $Id$ @c -@ifinfo -@node Semaphore Manager, Semaphore Manager Introduction, TIMER_RESET - Reset an interval timer, Top -@end ifinfo @chapter Semaphore Manager -@ifinfo -@menu -* Semaphore Manager Introduction:: -* Semaphore Manager Background:: -* Semaphore Manager Operations:: -* Semaphore Manager Directives:: -@end menu -@end ifinfo - -@ifinfo -@node Semaphore Manager Introduction, Semaphore Manager Background, Semaphore Manager, Semaphore Manager -@end ifinfo + @section Introduction The semaphore manager utilizes standard Dijkstra @@ -37,20 +23,7 @@ semaphore manager are: @item @code{@value{DIRPREFIX}semaphore_release} - Release a semaphore @end itemize -@ifinfo -@node Semaphore Manager Background, Nested Resource Access, Semaphore Manager Introduction, Semaphore Manager -@end ifinfo @section Background -@ifinfo -@menu -* Nested Resource Access:: -* Priority Inversion:: -* Priority Inheritance:: -* Priority Ceiling:: -* Building a Semaphore's Attribute Set:: -* Building a SEMAPHORE_OBTAIN Option Set:: -@end menu -@end ifinfo A semaphore can be viewed as a protected variable whose value can be modified only with the @@ -92,9 +65,6 @@ performs a corresponding @code{@value{DIRPREFIX}semaphore_release} operation when it reaches its synchronization point, thus unblocking the pending task. -@ifinfo -@node Nested Resource Access, Priority Inversion, Semaphore Manager Background, Semaphore Manager Background -@end ifinfo @subsection Nested Resource Access Deadlock occurs when a task owning a binary semaphore @@ -114,9 +84,6 @@ outermost @code{@value{DIRPREFIX}semaphore_obtain} is matched with a @code{@value{DIRPREFIX}semaphore_release}. -@ifinfo -@node Priority Inversion, Priority Inheritance, Nested Resource Access, Semaphore Manager Background -@end ifinfo @subsection Priority Inversion Priority inversion is a form of indefinite @@ -132,9 +99,6 @@ cannot complete its interaction with the resource and release that resource. The high priority task is effectively prevented from executing by lower priority tasks. -@ifinfo -@node Priority Inheritance, Priority Ceiling, Priority Inversion, Semaphore Manager Background -@end ifinfo @subsection Priority Inheritance Priority inheritance is an algorithm that calls for @@ -163,9 +127,6 @@ any of the semaphores the task holds. Only when the task releases ALL of the binary semaphores it holds will its priority be restored to the normal value. -@ifinfo -@node Priority Ceiling, Building a Semaphore's Attribute Set, Priority Inheritance, Semaphore Manager Background -@end ifinfo @subsection Priority Ceiling Priority ceiling is an algorithm that calls for the @@ -207,9 +168,6 @@ any of the semaphores the task holds. Only when the task releases ALL of the binary semaphores it holds will its priority be restored to the normal value. -@ifinfo -@node Building a Semaphore's Attribute Set, Building a SEMAPHORE_OBTAIN Option Set, Priority Ceiling, Semaphore Manager Background -@end ifinfo @subsection Building a Semaphore's Attribute Set In general, an attribute set is built by a bitwise OR @@ -263,9 +221,6 @@ similar semaphore were to be known globally, then the attribute_set parameter would be @code{@value{RPREFIX}GLOBAL @value{OR} @value{RPREFIX}PRIORITY}. -@ifinfo -@node Building a SEMAPHORE_OBTAIN Option Set, Semaphore Manager Operations, Building a Semaphore's Attribute Set, Semaphore Manager Background -@end ifinfo @subsection Building a SEMAPHORE_OBTAIN Option Set In general, an option is built by a bitwise OR of the @@ -292,23 +247,8 @@ to poll for a semaphore. The option parameter passed to the @code{@value{DIRPREFIX}semaphore_obtain} directive should be @code{@value{RPREFIX}NO_WAIT}. -@ifinfo -@node Semaphore Manager Operations, Creating a Semaphore, Building a SEMAPHORE_OBTAIN Option Set, Semaphore Manager -@end ifinfo @section Operations -@ifinfo -@menu -* Creating a Semaphore:: -* Obtaining Semaphore IDs:: -* Acquiring a Semaphore:: -* Releasing a Semaphore:: -* Deleting a Semaphore:: -@end menu -@end ifinfo - -@ifinfo -@node Creating a Semaphore, Obtaining Semaphore IDs, Semaphore Manager Operations, Semaphore Manager Operations -@end ifinfo + @subsection Creating a Semaphore The @code{@value{DIRPREFIX}semaphore_create} directive creates a binary or @@ -328,9 +268,6 @@ must be specified. RTEMS allocates a Semaphore Control Block RTEMS to manage the newly created semaphore. Also, a unique semaphore ID is generated and returned to the calling task. -@ifinfo -@node Obtaining Semaphore IDs, Acquiring a Semaphore, Creating a Semaphore, Semaphore Manager Operations -@end ifinfo @subsection Obtaining Semaphore IDs When a semaphore is created, RTEMS generates a unique @@ -344,9 +281,6 @@ the semaphore ID may be obtained later using the used by other semaphore manager directives to access this semaphore. -@ifinfo -@node Acquiring a Semaphore, Releasing a Semaphore, Obtaining Semaphore IDs, Semaphore Manager Operations -@end ifinfo @subsection Acquiring a Semaphore The @code{@value{DIRPREFIX}semaphore_obtain} directive is used to acquire the @@ -389,9 +323,6 @@ priority ceiling and the priority ceiling for this semaphore is greater than that of the holder, then the holder's priority will be elevated. -@ifinfo -@node Releasing a Semaphore, Deleting a Semaphore, Acquiring a Semaphore, Semaphore Manager Operations -@end ifinfo @subsection Releasing a Semaphore The @code{@value{DIRPREFIX}semaphore_release} directive is used to release @@ -412,9 +343,6 @@ the task does not currently hold any other binary semaphores, then the task performing the @code{@value{DIRPREFIX}semaphore_release} will have its priority restored to its normal value. -@ifinfo -@node Deleting a Semaphore, Semaphore Manager Directives, Releasing a Semaphore, Semaphore Manager Operations -@end ifinfo @subsection Deleting a Semaphore The @code{@value{DIRPREFIX}semaphore_delete} directive removes a semaphore @@ -425,19 +353,7 @@ the semaphore will be readied and returned a status code which indicates that the semaphore was deleted. Any subsequent references to the semaphore's name and ID are invalid. -@ifinfo -@node Semaphore Manager Directives, SEMAPHORE_CREATE - Create a semaphore, Deleting a Semaphore, Semaphore Manager -@end ifinfo @section Directives -@ifinfo -@menu -* SEMAPHORE_CREATE - Create a semaphore:: -* SEMAPHORE_IDENT - Get ID of a semaphore:: -* SEMAPHORE_DELETE - Delete a semaphore:: -* SEMAPHORE_OBTAIN - Acquire a semaphore:: -* SEMAPHORE_RELEASE - Release a semaphore:: -@end menu -@end ifinfo This section details the semaphore manager's directives. A subsection is dedicated to each of this manager's @@ -445,9 +361,6 @@ directives and describes the calling sequence, related constants, usage, and status codes. @page -@ifinfo -@node SEMAPHORE_CREATE - Create a semaphore, SEMAPHORE_IDENT - Get ID of a semaphore, Semaphore Manager Directives, Semaphore Manager Directives -@end ifinfo @subsection SEMAPHORE_CREATE - Create a semaphore @subheading CALLING SEQUENCE: @@ -549,9 +462,6 @@ semaphores, is limited by the maximum_global_objects field in the Configuration Table. @page -@ifinfo -@node SEMAPHORE_IDENT - Get ID of a semaphore, SEMAPHORE_DELETE - Delete a semaphore, SEMAPHORE_CREATE - Create a semaphore, Semaphore Manager Directives -@end ifinfo @subsection SEMAPHORE_IDENT - Get ID of a semaphore @subheading CALLING SEQUENCE: @@ -609,9 +519,6 @@ nodes. It accesses only the local copy of the global object table. @page -@ifinfo -@node SEMAPHORE_DELETE - Delete a semaphore, SEMAPHORE_OBTAIN - Acquire a semaphore, SEMAPHORE_IDENT - Get ID of a semaphore, Semaphore Manager Directives -@end ifinfo @subsection SEMAPHORE_DELETE - Delete a semaphore @subheading CALLING SEQUENCE: @@ -670,9 +577,6 @@ Proxies, used to represent remote tasks, are reclaimed when the semaphore is deleted. @page -@ifinfo -@node SEMAPHORE_OBTAIN - Acquire a semaphore, SEMAPHORE_RELEASE - Release a semaphore, SEMAPHORE_DELETE - Delete a semaphore, Semaphore Manager Directives -@end ifinfo @subsection SEMAPHORE_OBTAIN - Acquire a semaphore @subheading CALLING SEQUENCE: @@ -762,9 +666,6 @@ A clock tick is required to support the timeout functionality of this directive. @page -@ifinfo -@node SEMAPHORE_RELEASE - Release a semaphore, Message Manager, SEMAPHORE_OBTAIN - Acquire a semaphore, Semaphore Manager Directives -@end ifinfo @subsection SEMAPHORE_RELEASE - Release a semaphore @subheading CALLING SEQUENCE: |