Add chMsgPoll()
Posted: Fri Jun 29, 2018 2:45 am
A small addition to chmsg.c
Although it is possible to use chMsgPendingI() followed by chMsgWait() to implement a polled wait I thought a specific function would be cleaner.
I use the above added function in a thread sweeper (idle or other as required) which enables a "chThdExitandCleanup()" type function to be used in terminating threads.
Although it is possible to use chMsgPendingI() followed by chMsgWait() to implement a polled wait I thought a specific function would be cleaner.
Code: Select all
Index: chmsg.c
===================================================================
--- chmsg.c (revision 12120)
+++ chmsg.c (working copy)
@@ -133,6 +133,37 @@
}
/**
+ * @brief Poll to check for an incoming message.
+ * @post If a message is available the function @p chMsgGet() must be
+ * called in order to retrieve the message and then @p chMsgRelease()
+ * must be invoked in order to acknowledge the reception and send
+ * the answer.
+ * @note If the message is a pointer then you can assume that the data
+ * pointed by the message is stable until you invoke @p chMsgRelease()
+ * because the sending thread is suspended until then.
+ * @note The reference counter of the sender thread is not increased, the
+ * returned pointer is a temporary reference.
+ *
+ * @return Result of the poll.
+ * @retval A pointer to the thread carrying the message.
+ * @retval NULL if no incoming message waiting.
+ *
+ * @api
+ */
+thread_t *chMsgPoll(void) {
+ thread_t *tp = NULL;
+
+ chSysLock();
+ if (chMsgIsPendingI(currp)) {
+ tp = queue_fifo_remove(&currp->msgqueue);
+ tp->state = CH_STATE_SNDMSG;
+ }
+ chSysUnlock();
+
+ return tp;
+}
+
+/**
* @brief Releases a sender thread specifying a response message.
* @pre Invoke this function only after a message has been received
* using @p chMsgWait().
I use the above added function in a thread sweeper (idle or other as required) which enables a "chThdExitandCleanup()" type function to be used in terminating threads.