320 lines
12 KiB
Plaintext
320 lines
12 KiB
Plaintext
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/*
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ChibiOS/RT - Copyright (C) 2006-2007 Giovanni Di Sirio.
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This file is part of ChibiOS/RT.
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ChibiOS/RT is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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ChibiOS/RT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @defgroup kernel Kernel
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* The kernel is the portable part of ChibiOS/RT, this section documents the
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* various kernel subsystems.
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*/
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/**
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* @defgroup kernel_info Version Numbers and Identification
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* Kernel related settings and hooks.
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* @ingroup kernel
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*/
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/**
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* @defgroup config Configuration
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* Kernel related settings and hooks.
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* @ingroup kernel
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*/
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/**
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* @defgroup types Types
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* System types and macros.
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* @ingroup kernel
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*/
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/**
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* @defgroup base Base Kernel Services
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* Base kernel services, the base subsystems are always included in the
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* OS builds.
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* @ingroup kernel
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*/
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/**
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* @defgroup system System Management
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* Initialization, Locks, Interrupt Handling, Power Management, Abnormal
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* Termination.
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* @ingroup base
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*/
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/**
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* @defgroup time Time and Virtual Timers
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* Time and Virtual Timers related APIs.
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* @ingroup base
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*/
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/**
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* @defgroup scheduler Scheduler
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* ChibiOS/RT scheduler APIs and macros.
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* @ingroup base
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*/
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/**
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* @defgroup threads Threads
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* Threads related APIs.
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* @ingroup base
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*/
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/**
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* @defgroup synchronization Synchronization
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* Synchronization services.
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* @ingroup kernel
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*/
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/**
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* @defgroup semaphores Semaphores
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* Semaphores and threads synchronization.
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* <h2>Operation mode</h2>
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* A semaphore is a threads synchronization object, some operations
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* are defined on semaphores:
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* - <b>Signal</b>: The semaphore counter is increased and if the result
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* is non-positive then a waiting thread is removed from the semaphore
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* queue and made ready for execution.
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* - <b>Wait</b>: The semaphore counter is decreased and if the result
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* becomes negative the thread is queued in the semaphore and suspended.
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* - <b>Reset</b>: The semaphore counter is reset to a non-negative value
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* and all the threads in the queue are released.
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* .
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* Semaphores can be used as guards for mutual exclusion code zones (note that
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* mutexes are recommended for this kind of use) but also have other uses,
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* queues guards and counters as example.<br>
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* Semaphores usually use FIFO queues but it is possible to make them
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* order threads by priority by specifying CH_USE_SEMAPHORES_PRIORITY in
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* @p chconf.h.<br>
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* In order to use the Semaphores APIs the @p CH_USE_SEMAPHORES
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* option must be specified in @p chconf.h.<br><br>
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* @ingroup synchronization
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*/
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/**
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* @defgroup mutexes Mutexes
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* Mutexes and threads synchronization.
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* <h2>Operation mode</h2>
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* A mutex is a threads synchronization object, some operations are defined
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* on mutexes:
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* - <b>Lock</b>: The mutex is checked, if the mutex is not owned by some
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* other thread then it is locked else the current thread is queued on the
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* mutex in a list ordered by priority.
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* - <b>Unlock</b>: The mutex is released by the owner and the highest
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* priority thread waiting in the queue, if any, is resumed and made owner
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* of the mutex.
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* .
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* In order to use the Event APIs the @p CH_USE_MUTEXES option must be
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* specified in @p chconf.h.<br>
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*
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* <h2>Constraints</h2>
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* In ChibiOS/RT the Unlock operations are always performed in Lock-reverse
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* order. The Unlock API does not even have a parameter, the mutex to unlock
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* is taken from an internal stack of owned mutexes.
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* This both improves the performance and is required by an efficient
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* implementation of the priority inheritance mechanism.
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*
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* <h2>The priority inversion problem</h2>
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* The mutexes in ChibiOS/RT implements the <b>full</b> priority
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* inheritance mechanism in order handle the priority inversion problem.<br>
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* When a thread is queued on a mutex, any thread, directly or indirectly,
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* holding the mutex gains the same priority of the waiting thread (if their
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* priority was not already equal or higher). The mechanism works with any
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* number of nested mutexes and any number of involved threads. The algorithm
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* complexity (worst case) is N with N equal to the number of nested mutexes.
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* @ingroup synchronization
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*/
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/**
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* @defgroup condvars Condition Variables
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* Condition Variables and threads synchronization.
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* <h2>Operation mode</h2>
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* The condition variable is a synchronization object meant to be used inside
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* a zone protected by a @p Mutex. Mutexes and CondVars together can implement
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* a Monitor construct.<br>
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* In order to use the Condition Variables APIs the @p CH_USE_CONDVARS
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* option must be specified in @p chconf.h.<br><br>
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* @ingroup synchronization
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*/
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/**
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* @defgroup events Event Flags
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* @brief Event Flags, Event Sources and Event Listeners.
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* <h2>Operation mode</h2>
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* Each thread has a mask of pending event flags inside its Thread structure.
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* Several operations are defined:
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* - <b>Wait</b>, the invoking thread goes to sleep until a certain AND/OR
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* combination of event flags becomes pending.
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* - <b>Clear</b>, a mask of event flags is cleared from the pending events
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* mask, the cleared event flags mask is returned (only the flags that were
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actually pending and then cleared).
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* - <b>Signal</b>, an event mask is directly ORed to the mask of the signaled
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* thread.
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* - <b>Broadcast</b>, each thread registered on an Event Source is signaled
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* with the event flags specified in its Event Listener.
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* - <b>Dispatch</b>, an events mask is scanned and for each bit set to one
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* an associated handler function is invoked. Bit masks are scanned from bit
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* zero upward.
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* .
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* An Event Source is a special object that can be "broadcasted" by a thread or
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* an interrupt service routine. Broadcasting an Event Source has the effect
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* that all the threads registered on the Event Source will be signaled with
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* and events mask.<br>
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* An unlimited number of Event Sources can exists in a system and each
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* thread can listen on an unlimited number of them.<br><br>
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* In order to use the Event APIs the @p CH_USE_EVENTS option must be
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* specified in @p chconf.h.
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* @ingroup synchronization
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*/
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/**
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* @defgroup messages Synchronous Messages
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* Synchronous inter-thread messages.
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* <h2>Operation Mode</h2>
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* Synchronous messages are an easy to use and fast IPC mechanism, threads
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* can both serve messages and send messages to other threads, the mechanism
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* allows data to be carried in both directions. Data is not copied between
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* the client and server threads but just a pointer passed so the exchange
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* is very time efficient.<br>
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* Messages are usually processed in FIFO order but it is possible to process
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* them in priority order by specifying CH_USE_MESSAGES_PRIORITY
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* in @p chconf.h.<br>
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* Threads do not need to allocate space for message queues, the mechanism
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* just requires two extra pointers in the @p Thread structure (the message
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* queue header).<br>
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* In order to use the Messages APIs the @p CH_USE_MESSAGES option must be
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* specified in @p chconf.h.
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* @ingroup synchronization
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*/
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/**
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* @defgroup mailboxes Mailboxes
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* Asynchronous messages.
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* <h2>Operation mode</h2>
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* A mailbox is an asynchronous communication mechanism.<br>
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* The following operations are possible on a mailbox:
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* - <b>Post</b>: Posts a message on the mailbox in FIFO order.
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* - <b>Post Ahead</b>: Posts a message on the mailbox with high priority.
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* - <b>Fetch</b>: A message is fetched from the mailbox and removed from
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* the queue.
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* - <b>Reset</b>: The mailbox is emptied and all the stored messages lost.
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* .
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* A message is a variable of type msg_t that is guaranteed to have the
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* same size of and be compatible with pointers (an explicit cast is needed).
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* If larger messages need to be exchanged then a pointer to a structure can
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* be posted in the mailbox but the posting side has no predefined way to
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* know when the message has been processed. A possible approach is to
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* allocate memory (from a memory pool as example) from the posting side and
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* free it on the fetching side. Another approach is to set a "done" flag into
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* the structure pointed by the message.
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* @ingroup synchronization
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*/
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/**
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* @defgroup memory Memory Management
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* Memory Management services.
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* @ingroup kernel
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*/
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/**
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* @defgroup heap Heap
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* Heap Allocator related APIs.
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* <h2>Operation mode</h2>
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* The heap allocator implements a first-fit strategy and its APIs are
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* functionally equivalent to the usual @p malloc() and @p free(). The main
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* difference is that the heap APIs are thread safe.<br>
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* By enabling the @p CH_USE_MALLOC_HEAP option the heap manager will use the
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* runtime-provided @p malloc() and @p free() as backend for the heap APIs
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* instead of the system provided allocator.<br>
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* In order to use the heap APIs the @p CH_USE_HEAP option must be specified
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* in @p chconf.h.
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* @ingroup memory
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*/
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/**
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* @defgroup pools Memory Pools
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* Memory Pools related APIs.
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* <h2>Operation mode</h2>
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* The Memory Pools APIs allow to allocate/free fixed size objects in
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* <b>constant time</b> and reliably without memory fragmentation problems.<br>
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* In order to use the Time APIs the @p CH_USE_MEMPOOLS option must be
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* specified in @p chconf.h.
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* @ingroup memory
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*/
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/**
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* @defgroup io_support I/O Support
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* I/O related services.
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* @ingroup kernel
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*/
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/**
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* @defgroup io_channels I/O Abstract Channels
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* @brief Abstract I/O Channels.
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* @details This module defines an abstract interface for I/O channels. Note
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* that no code is present, I/O channels are just abstract classes-like
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* structures, you should look at the systems as to a set of abstract C++
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* classes (even if written in C). Specific device drivers can use/extend
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* the interfaces and implement them.<br>
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* This system has the advantage to make the access to channels
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* independent from the implementation logic. As example, an I/O channel
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* interface can hide the access to a serial driver, to a networking socket
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* and so on.
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*
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* @ingroup io_support
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*/
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/**
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* @defgroup io_queues I/O Queues
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* @brief I/O queues.
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* @details ChibiOS/RT supports several kinds of queues. The queues are mostly
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* used in serial-like device drivers. The device drivers are usually designed
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* to have a lower side (lower driver, it is usually an interrupt service
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* routine) and an upper side (upper driver, accessed by the application
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* threads).<br>
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* There are several kind of queues:<br>
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* - <b>Input queue</b>, unidirectional queue where the writer is the
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* lower side and the reader is the upper side.
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* - <b>Output queue</b>, unidirectional queue where the writer is the
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* upper side and the reader is the lower side.
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* - <b>Full duplex queue</b>, bidirectional queue where read and write
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* operations can happen at the same time. Full duplex queues
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* are implemented by pairing an input queue and an output queue together.
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* .
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* In order to use the I/O queues the @p CH_USE_QUEUES option must
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* be specified in @p chconf.h.<br>
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*
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* @ingroup io_support
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*/
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/**
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* @defgroup debug Debug
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* Debug APIs and procedures.
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* @ingroup kernel
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*/
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/**
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* @defgroup core Port Templates
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* Non portable code templates.
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* @ingroup kernel
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*/
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/**
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* @defgroup internals Internals
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* Internal details, not APIs.
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* @ingroup kernel
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*/
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