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Change-Id: Iefe6ece780ebb903819190bf75b0e6b704c54bb0 Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/67260 Pigweed-Auto-Submit: Ewout van Bekkum <ewout@google.com> Reviewed-by: Keir Mierle <keir@google.com> Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
46 lines
1.6 KiB
ReStructuredText
46 lines
1.6 KiB
ReStructuredText
.. _module-pw_sync_embos:
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=============
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pw_sync_embos
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=============
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This is a set of backends for pw_sync based on embOS v4.
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--------------------------------
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Critical Section Lock Primitives
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--------------------------------
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Mutex & TimedMutex
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==================
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The embOS v4 backend for the Mutex and TimedMutex use ``OS_RSEMA`` as the
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underlying type. It is created using ``OS_CreateRSema`` as part of the
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constructors and cleaned up using ``OS_DeleteRSema`` in the destructors.
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InterruptSpinLock
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=================
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The embOS v4 backend for InterruptSpinLock is backed by a ``bool`` which permits
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these objects to detect accidental recursive locking.
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This object uses ``OS_IncDI`` and ``OS_DecRI`` to mask interrupts which enables
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the critical section. In addition, ``OS_SuspendAllTasks`` and
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``OS_ResumeAllSuspendedTasks`` are used to to prevent accidental thread context
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switches while the InterruptSpinLock is locked.
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--------------------
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Signaling Primitives
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--------------------
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ThreadNotification & TimedThreadNotification
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============================================
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The native embOS v4 implementation of its semaphores (``OS_CSEMA``) is very
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efficient, ergo we recommend using the binary semaphore backends for
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ThreadNotifications:
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- ``pw_sync:binary_semaphore_thread_notification_backend``
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- ``pw_sync:binary_semaphore_timed_thread_notification_backend``
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BinarySemaphore & CountingSemaphore
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===================================
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The embOS v4 backends for the BinarySemaphore and CountingSemaphore use
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``OS_CSEMA`` as the underlying type. It is created using ``OS_CreateCSema`` as
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part of the constructor and cleaned up using ``OS_DeleteCSema`` in the
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destructor.
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