/* ChibiOS/RT - Copyright (C) 2006-2007 Giovanni Di Sirio. This file is part of ChibiOS/RT. ChibiOS/RT is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. ChibiOS/RT is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . */ /** * @mainpage ChibiOS/RT * @author Giovanni Di Sirio (gdisirio@users.sourceforge.net). * *

Chibi ?

* I didn't want a serious name for this project. It is the Japanese word for * small as in small child. So ChibiOS/RT * @htmlonly (ちびOS/RT) @endhtmlonly * means small Real Time Operating System. * Source Wikipedia. * *

Features

* - Free software, GPL3 licensed. Stable releases include a exception clause * to the GPL. * - Designed for realtime applications. * - Easily portable. * - Preemptive scheduling. * - 128 priority levels. Multiple threads at the same priority level allowed. * - Round robin scheduling for threads at the same priority level. * - Offers threads, virtual timers, semaphores, mutexes, condvars, * event flags, messages, mailboxes, I/O queues. * - No static setup at compile time, there is no need to configure a maximum * number of all the above objects. * - PC simulator target included, the development can be done on the PC * using MinGW.
* Timers, I/O channels and other HW resources are simulated in a * Win32 process and the application code does not need to be aware of it. * MinGW demo available. * - No *need* for a memory allocator, all the kernel structures are static * and declaratively allocated. * - Optional, thread safe, Heap Allocator subsystem. * - Optional, thread safe, Memory Pools Allocator subsystem. * - Blocking and non blocking I/O channels with timeout and events generation * capability. * - Minimal system requirements: about 8KiB ROM with all options enabled and * speed optimizations on. The size can shrink under 2KiB by disabling the * the unused subsystems and optimizing for size. * - Almost totally written in C with little ASM code required for ports. * . *

Related pages

* - @subpage lic_faq * - @subpage goals * - @subpage concepts * - @subpage articles * . */ /** * @defgroup Ports Ports * This section describes the technical details for the various supported * ChibiOS/RT ports. */ /** * @defgroup Kernel Kernel * Kernel related subsystems, */ /** * @defgroup Config Configuration * In @p chconf.h are defined the required subsystems for your application. * @ingroup Kernel */ /** * @defgroup Core Generic Port Code Templates * Non portable code templates. * @ingroup Kernel */ /** * @defgroup Types Types * System types and macros. * @ingroup Kernel */ /** * @defgroup System System Management * Initialization, Locks, Interrupt Handling, Power Management, Abnormal * Termination. * @ingroup Kernel */ /** * @defgroup Inline Inline * System inline-able code. * @ingroup Kernel */ /** * @defgroup Debug Debug * Debug APIs and procedures. * @ingroup Kernel */ /** * @defgroup Scheduler Scheduler * ChibiOS/RT scheduler. * @ingroup Kernel */ /** * @defgroup ThreadLists Thread Lists and Queues * ChibiOS/RT thread lists and queues utilities. * @ingroup Kernel */ /** * @defgroup Threads Threads * Threads creation and termination APIs. */ /** * @defgroup Time Time and Virtual Timers * Time and Virtual Timers related APIs. */ /** * @defgroup Heap Heap * Heap Allocator related APIs. *

Operation mode

* The heap allocator implements a first-fit strategy and its APIs are * functionally equivalent to the usual @p malloc() and @p free(). The main * difference is that the heap APIs are thread safe.
* By enabling the @p CH_USE_MALLOC_HEAP option the heap manager will use the * runtime-provided @p malloc() and @p free() as backend for the heap APIs * instead of the system provided allocator.
* In order to use the heap APIs the @p CH_USE_HEAP option must be specified * in @p chconf.h. */ /** * @defgroup MemoryPools Memory Pools * Memory Pools related APIs. *

Operation mode

* The Memory Pools APIs allow to allocate/free fixed size objects in * constant time and reliably without memory fragmentation problems.
* In order to use the Time APIs the @p CH_USE_MEMPOOLS option must be * specified in @p chconf.h. */ /** * @defgroup Semaphores Semaphores * Semaphores and threads synchronization. *

Operation mode

* A semaphore is a threads synchronization object, some operations * are defined on semaphores: * - Signal: The semaphore counter is increased and if the result * is non-positive then a waiting thread is removed from the semaphore * queue and made ready for execution. * - Wait: The semaphore counter is decreased and if the result * becomes negative the thread is queued in the semaphore and suspended. * - Reset: The semaphore counter is reset to a non-negative value * and all the threads in the queue are released. * . * Semaphores can be used as guards for mutual exclusion code zones (note that * mutexes are recommended for this kind of use) but also have other uses, * queues guards and counters as example.
* Semaphores usually use FIFO queues but it is possible to make them * order threads by priority by specifying CH_USE_SEMAPHORES_PRIORITY in * @p chconf.h.
* In order to use the Semaphores APIs the @p CH_USE_SEMAPHORES * option must be specified in @p chconf.h.

*/ /** * @defgroup Mutexes Mutexes * Mutexes and threads synchronization. *

Operation mode

* A mutex is a threads synchronization object, some operations are defined * on mutexes: * - Lock: The mutex is checked, if the mutex is not owned by some * other thread then it is locked else the current thread is queued on the * mutex in a list ordered by priority. * - Unlock: The mutex is released by the owner and the highest * priority thread waiting in the queue, if any, is resumed and made owner * of the mutex. * . * In order to use the Event APIs the @p CH_USE_MUTEXES option must be * specified in @p chconf.h.
* *

Constraints

* In ChibiOS/RT the Unlock operations are always performed in Lock-reverse * order. The Unlock API does not even have a parameter, the mutex to unlock * is taken from an internal stack of owned mutexes. * This both improves the performance and is required by the priority * inheritance mechanism. * *

The priority inversion problem

* The mutexes in ChibiOS/RT implements the full priority * inheritance mechanism in order handle the priority inversion problem.
* When a thread is queued on a mutex, any thread, directly or indirectly, * holding the mutex gains the same priority of the waiting thread (if their * priority was not already equal or higher). The mechanism works with any * number of nested mutexes and any number of involved threads. The algorithm * complexity (worst case) is N with N equal to the number of nested mutexes. */ /** * @defgroup CondVars Condition Variables * Condition Variables and threads synchronization. *

Operation mode

* The condition variable is a synchronization object meant to be used inside * a zone protected by a @p Mutex. Mutexes and CondVars together can implement * a Monitor construct.
* In order to use the Condition Variables APIs the @p CH_USE_CONDVARS * option must be specified in @p chconf.h.

*/ /** * @defgroup Events Events * Event Sources and Event Listeners. *

Operation mode

* An Event Source is a special object that can be signaled by a thread or * an interrupt service routine. Signaling an Event Source has the effect * that all the threads registered on the Event Source will receive * and serve the event.
* An unlimited number of Event Sources can exists in a system and each * thread can listen on an unlimited number of them.
* Note that the events can be asynchronously generated but are synchronously * served, a thread can serve event by calling a @p chEvtWaitXXX() * API. If an event is generated while a listening thread is not ready to * serve it then the event becomes "pending" and will be served as soon the * thread invokes a @p chEvtWaitXXX().
* In order to use the Event APIs the @p CH_USE_EVENTS option must be * specified in @p chconf.h. */ /** * @defgroup Messages Synchronous Messages * Synchronous inter-thread messages. *

Operation Mode

* Synchronoud messages are an easy to use and fast IPC mechanism, threads * can both serve messages and send messages to other threads, the mechanism * allows data to be carried in both directions. Data is not copied between * the client and server threads but just a pointer passed so the exchange * is very time efficient.
* Messages are usually processed in FIFO order but it is possible to process * them in priority order by specifying CH_USE_MESSAGES_PRIORITY * in @p chconf.h.
* Threads do not need to allocate space for message queues, the mechanism * just requires two extra pointers in the @p Thread structure (the message * queue header).
* In order to use the Messages APIs the @p CH_USE_MESSAGES option must be * specified in @p chconf.h. */ /** * @defgroup Mailboxes Mailboxes * Asynchronous messages. *

Operation mode

* A mailbox is an asynchronous communication mechanism.
* The following operations are possible on a mailbox: * - Post: Posts a message on the mailbox in FIFO order. * - Post Ahead: Posts a message on the mailbox with high priority. * - Fetch: A message is fetched from the mailbox and removed from * the queue. * - Reset: The mailbox is emptied and all the stored messages lost. * . * A message is a variable of type msg_t that is guaranteed to have the * same size of and be compatible with pointers (an explicit cast is needed). * If larger messages need to be exchanged then a pointer to a structure can * be posted in the mailbox but the posting side has no predefined way to * know when the message has been processed. A possible approach is to * allocate memory (from a memory pool as example) from the posting side and * free it on the fetching side. Another approach is to set a "done" flag into * the structure pointed by the message. */ /** * @defgroup IOQueues Physical I/O Queues * ChibiOS/RT supports several kinds of queues. The queues are mostly used * in serial-like device drivers. The device drivers are usually designed to * have a lower side (lower driver, it is usually an interrupt service * routine) and an upper side (upper driver, accessed by the application * threads).
* There are several kind of queues:
* - Input queue, unidirectional queue where the writer is the * lower side and the reader is the upper side. * - Output queue, unidirectional queue where the writer is the * upper side and the reader is the lower side. * - Full duplex queue, bidirectional queue where read and write * operations can happen at the same time. Full duplex queues * are implemented by pairing an input queue and an output queue together. * . * In order to use the I/O queues the @p CH_USE_QUEUES option must * be specified in @p chconf.h.
*/ /** * @defgroup Channels Abstract I/O Channels * This module defines an abstract interface for I/O channels. Note that * no code is present, I/O channels are just abstract classes-like structures, * you should look at the systems as to a set of abstract C++ classes (even if * implemented in C). Specific device drivers can use/extend the interfaces * and implement them.
* This system has the advantage to make the access to the device drivers * independent from the implementation logic. As example, an I/O channel * interface can hide the access to a serial driver, to a networking socket * and so on. */ /** * @defgroup Serial Serial Drivers * This module implements a generic full duplex serial driver and a generic * half duplex serial driver. It uses the I/O Queues for communication between * the upper and the lower driver and events to notify the application about * incoming data, outcoming data and other I/O events. * The module also contains functions that make the implementation of the * interrupt service routines much easier.
* In order to use the serial full duplex driver the * @p CH_USE_SERIAL_FULLDUPLEX option must be specified in @p chconf.h.
* In order to use the serial half duplex driver the * @p CH_USE_SERIAL_HALFDUPLEX option must be specified in @p chconf.h. */ /** * @defgroup utilities_library Utilities Library * @brief Utilities Library. * @details This is a collection of useful library code that is not part of * the base kernel services. *

Notes

* The library code does not follow the same naming convention of the * system APIs in order to make very clear that it is not "core" code.
* The main difference is that library code is not formally tested in the * test suite but through usage in the various demo applications. */ /** * @defgroup CPlusPlusLibrary C++ Wrapper * @brief C++ wrapper module. * @details This module allows to use the ChibiOS/RT functionalities * from C++ as classes and objects rather the traditional "C" APIs. * * @ingroup utilities_library */ /** * @defgroup event_timer Events Generator Timer * @brief Event Generator Timer. * @details This timer generates an event at regular intervals. The * listening threads can use the event to perform time related activities. * Multiple threads can listen to the same timer. * * @ingroup utilities_library */