| /* |
| * Copyright (c) 2008-2009 Travis Geiselbrecht |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining |
| * a copy of this software and associated documentation files |
| * (the "Software"), to deal in the Software without restriction, |
| * including without limitation the rights to use, copy, modify, merge, |
| * publish, distribute, sublicense, and/or sell copies of the Software, |
| * and to permit persons to whom the Software is furnished to do so, |
| * subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be |
| * included in all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
| * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY |
| * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, |
| * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE |
| * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
| */ |
| |
| /** |
| * @file |
| * @brief Event wait and signal functions for threads. |
| * @defgroup event Events |
| * |
| * An event is a subclass of a wait queue. |
| * |
| * Threads wait for events, with optional timeouts. |
| * |
| * Events are "signaled", releasing waiting threads to continue. |
| * Signals may be one-shot signals (EVENT_FLAG_AUTOUNSIGNAL), in which |
| * case one signal releases only one thread, at which point it is |
| * automatically cleared. Otherwise, signals release all waiting threads |
| * to continue immediately until the signal is manually cleared with |
| * event_unsignal(). |
| * |
| * @{ |
| */ |
| |
| #include <debug.h> |
| #include <err.h> |
| #include <kernel/event.h> |
| |
| #if DEBUGLEVEL > 1 |
| #define EVENT_CHECK 1 |
| #endif |
| |
| /** |
| * @brief Initialize an event object |
| * |
| * @param e Event object to initialize |
| * @param initial Initial value for "signaled" state |
| * @param flags 0 or EVENT_FLAG_AUTOUNSIGNAL |
| */ |
| void event_init(event_t *e, bool initial, uint flags) |
| { |
| #if EVENT_CHECK |
| // ASSERT(e->magic != EVENT_MAGIC); |
| #endif |
| |
| e->magic = EVENT_MAGIC; |
| e->signalled = initial; |
| e->flags = flags; |
| wait_queue_init(&e->wait); |
| } |
| |
| /** |
| * @brief Destroy an event object. |
| * |
| * Event's resources are freed and it may no longer be |
| * used until event_init() is called again. Any threads |
| * still waiting on the event will be resumed. |
| * |
| * @param e Event object to initialize |
| */ |
| void event_destroy(event_t *e) |
| { |
| enter_critical_section(); |
| |
| #if EVENT_CHECK |
| ASSERT(e->magic == EVENT_MAGIC); |
| #endif |
| |
| e->magic = 0; |
| e->signalled = false; |
| e->flags = 0; |
| wait_queue_destroy(&e->wait, true); |
| |
| exit_critical_section(); |
| } |
| |
| /** |
| * @brief Wait for event to be signaled |
| * |
| * If the event has already been signaled, this function |
| * returns immediately. Otherwise, the current thread |
| * goes to sleep until the event object is signaled, |
| * the timeout is reached, or the event object is destroyed |
| * by another thread. |
| * |
| * @param e Event object |
| * @param timeout Timeout value, in ms |
| * |
| * @return 0 on success, ERR_TIMED_OUT on timeout, |
| * other values on other errors. |
| */ |
| status_t event_wait_timeout(event_t *e, time_t timeout) |
| { |
| status_t ret = NO_ERROR; |
| |
| enter_critical_section(); |
| |
| #if EVENT_CHECK |
| ASSERT(e->magic == EVENT_MAGIC); |
| #endif |
| |
| if (e->signalled) { |
| /* signalled, we're going to fall through */ |
| if (e->flags & EVENT_FLAG_AUTOUNSIGNAL) { |
| /* autounsignal flag lets one thread fall through before unsignalling */ |
| e->signalled = false; |
| } |
| } else { |
| /* unsignalled, block here */ |
| ret = wait_queue_block(&e->wait, timeout); |
| if (ret < 0) |
| goto err; |
| } |
| |
| err: |
| exit_critical_section(); |
| |
| return ret; |
| } |
| |
| /** |
| * @brief Same as event_wait_timeout(), but without a timeout. |
| */ |
| status_t event_wait(event_t *e) |
| { |
| return event_wait_timeout(e, INFINITE_TIME); |
| } |
| |
| /** |
| * @brief Signal an event |
| * |
| * Signals an event. If EVENT_FLAG_AUTOUNSIGNAL is set in the event |
| * object's flags, only one waiting thread is allowed to proceed. Otherwise, |
| * all waiting threads are allowed to proceed until such time as |
| * event_unsignal() is called. |
| * |
| * @param e Event object |
| * @param reschedule If true, waiting thread(s) are executed immediately, |
| * and the current thread resumes only after the |
| * waiting threads have been satisfied. If false, |
| * waiting threads are placed at the end of the run |
| * queue. |
| * |
| * @return Returns NO_ERROR on success. |
| */ |
| status_t event_signal(event_t *e, bool reschedule) |
| { |
| enter_critical_section(); |
| |
| #if EVENT_CHECK |
| ASSERT(e->magic == EVENT_MAGIC); |
| #endif |
| |
| if (!e->signalled) { |
| if (e->flags & EVENT_FLAG_AUTOUNSIGNAL) { |
| /* try to release one thread and leave unsignalled if successful */ |
| if (wait_queue_wake_one(&e->wait, reschedule, NO_ERROR) <= 0) { |
| /* |
| * if we didn't actually find a thread to wake up, go to |
| * signalled state and let the next call to event_wait |
| * unsignal the event. |
| */ |
| e->signalled = true; |
| } |
| } else { |
| /* release all threads and remain signalled */ |
| e->signalled = true; |
| wait_queue_wake_all(&e->wait, reschedule, NO_ERROR); |
| } |
| } |
| |
| exit_critical_section(); |
| |
| return NO_ERROR; |
| } |
| |
| /** |
| * @brief Clear the "signaled" property of an event |
| * |
| * Used mainly for event objects without the EVENT_FLAG_AUTOUNSIGNAL |
| * flag. Once this function is called, threads that call event_wait() |
| * functions will once again need to wait until the event object |
| * is signaled. |
| * |
| * @param e Event object |
| * |
| * @return Returns NO_ERROR on success. |
| */ |
| status_t event_unsignal(event_t *e) |
| { |
| enter_critical_section(); |
| |
| #if EVENT_CHECK |
| ASSERT(e->magic == EVENT_MAGIC); |
| #endif |
| |
| e->signalled = false; |
| |
| exit_critical_section(); |
| |
| return NO_ERROR; |
| } |
| |