diff options
Diffstat (limited to 'os/kernel/src/chsem.c')
| -rw-r--r-- | os/kernel/src/chsem.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/os/kernel/src/chsem.c b/os/kernel/src/chsem.c index 439412d7c..2a86a14f6 100644 --- a/os/kernel/src/chsem.c +++ b/os/kernel/src/chsem.c @@ -22,11 +22,20 @@ * @brief Semaphores code.
*
* @addtogroup semaphores
- * @details Semaphores and threads synchronization.
+ * @details Semaphores related APIs and services.
*
* <h2>Operation mode</h2>
- * A semaphore is a threads synchronization object, some operations
- * are defined on semaphores:
+ * Semaphores are a flexible synchronization primitive, ChibiOS/RT
+ * implements semaphores in their "counting semaphores" variant as
+ * defined by Edsger Dijkstra plus several enhancements like:
+ * - Wait operation with timeout.
+ * - Reset operation.
+ * - Atomic wait+signal operation.
+ * - Return message from the wait operation (OK, RESET, TIMEOUT).
+ * .
+ * The binary semaphores variant can be easily implemented using
+ * counting semaphores.<br>
+ * Operations defined for semaphores:
* - <b>Signal</b>: 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.
@@ -36,9 +45,9 @@ * - <b>Reset</b>: 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.<br>
+ * Semaphores can be used as guards for mutual exclusion zones
+ * (note that mutexes are recommended for this kind of use) but
+ * also have other uses, queues guards and counters as example.<br>
* Semaphores usually use a FIFO queuing strategy but it is possible
* to make them order threads by priority by enabling
* @p CH_USE_SEMAPHORES_PRIORITY in @p chconf.h.<br>
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