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| author | gdisirio <gdisirio@35acf78f-673a-0410-8e92-d51de3d6d3f4> | 2009-01-19 13:31:37 +0000 |
|---|---|---|
| committer | gdisirio <gdisirio@35acf78f-673a-0410-8e92-d51de3d6d3f4> | 2009-01-19 13:31:37 +0000 |
| commit | 0810f1daac3c33d194d573d82ec436021e3e7255 (patch) | |
| tree | 41909345afc1c1e949a18119563243b9adfc8648 /docs/src/atomic.dox | |
| parent | f8b4fca89a8dd31989a3d21e4c6fb4175aba4110 (diff) | |
| download | ChibiOS-0810f1daac3c33d194d573d82ec436021e3e7255.tar.gz ChibiOS-0810f1daac3c33d194d573d82ec436021e3e7255.tar.bz2 ChibiOS-0810f1daac3c33d194d573d82ec436021e3e7255.zip | |
git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@643 35acf78f-673a-0410-8e92-d51de3d6d3f4
Diffstat (limited to 'docs/src/atomic.dox')
| -rw-r--r-- | docs/src/atomic.dox | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/docs/src/atomic.dox b/docs/src/atomic.dox new file mode 100644 index 000000000..0f678448b --- /dev/null +++ b/docs/src/atomic.dox @@ -0,0 +1,50 @@ +/**
+ * @page article_atomic Invoking multiple primitives as a single atomic operation
+ * @{
+ * It is often necessary to invoke multiple operations involving a
+ * reschedulation as a single atomic operation.<br>
+ * ChibiOS/RT already implements APIs that perform complex operations, as
+ * example the API @p chSemSignalWait() performs two operations atomically.<br>
+ * If more complex operations are required in your application then it is
+ * possible to build macro-operations, see the following example:
+ * @code
+ chSysLock();
+
+ chSemSignalI(&sem1);
+ chSemSignalI(&sem2);
+ if (tp != NULL) {
+ chThdResumeI(tp);
+ tp = NULL;
+ }
+ chSchRescheduleS();
+
+ chSysUnlock();
+ * @endcode
+ * The above example performs a signal operation on two semaphores, optionally
+ * resumes a thread, and performs a final reschedulation. The three operations
+ * are performed atomically.<br>
+ * An hypotetical @p chSemSignalSignalWait() operation could be implemented as
+ * follow:
+ * @code
+ chSysLock();
+
+ chSemSignalI(&sem1);
+ chSemSignalI(&sem2);
+ /*
+ * The "if" is required because the chSemWaitS() does not always internally
+ * reschedule.
+ */
+ if (chSemGetCounter(&sem3) <= 0)
+ chSemWaitS(&Sem3);
+ else {
+ chSemFastWaitS(&sem3);
+ chSchRescheduleS();
+ }
+
+ chSysUnlock();
+ * @endcode
+ * In general multiple I-Class APIs can be included and the block is terminated
+ * by an S-Class API that performs a reschedulation. Optionally a
+ * @p chSchRescheduleS() is present at the very end of the block.
+ */
+/** @} */
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