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Diffstat (limited to 'os/rt/src/chmsg.c')
| -rw-r--r-- | os/rt/src/chmsg.c | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/os/rt/src/chmsg.c b/os/rt/src/chmsg.c new file mode 100644 index 000000000..335b46c61 --- /dev/null +++ b/os/rt/src/chmsg.c @@ -0,0 +1,151 @@ +/*
+ ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
+ 2011,2012,2013 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 <http://www.gnu.org/licenses/>.
+*/
+
+/**
+ * @file chmsg.c
+ * @brief Messages code.
+ *
+ * @addtogroup messages
+ * @details Synchronous inter-thread messages APIs and services.
+ * <h2>Operation Mode</h2>
+ * Synchronous messages are an easy to use and fast IPC mechanism,
+ * threads can both act as message servers and/or message clients,
+ * the mechanism allows data to be carried in both directions. Note
+ * that messages are not copied between the client and server threads
+ * but just a pointer passed so the exchange is very time
+ * efficient.<br>
+ * Messages are scalar data types of type @p msg_t that are guaranteed
+ * to be size compatible with data pointers. Note that on some
+ * architectures function pointers can be larger that @p msg_t.<br>
+ * Messages are usually processed in FIFO order but it is possible to
+ * process them in priority order by enabling the
+ * @p CH_CFG_USE_MESSAGES_PRIORITY option in @p chconf.h.<br>
+ * @pre In order to use the message APIs the @p CH_CFG_USE_MESSAGES option
+ * must be enabled in @p chconf.h.
+ * @post Enabling messages requires 6-12 (depending on the architecture)
+ * extra bytes in the @p thread_t structure.
+ * @{
+ */
+
+#include "ch.h"
+
+#if CH_CFG_USE_MESSAGES || defined(__DOXYGEN__)
+
+/*===========================================================================*/
+/* Module exported variables. */
+/*===========================================================================*/
+
+/*===========================================================================*/
+/* Module local types. */
+/*===========================================================================*/
+
+/*===========================================================================*/
+/* Module local variables. */
+/*===========================================================================*/
+
+/*===========================================================================*/
+/* Module local functions. */
+/*===========================================================================*/
+
+#if CH_CFG_USE_MESSAGES_PRIORITY
+#define msg_insert(tp, qp) prio_insert(tp, qp)
+#else
+#define msg_insert(tp, qp) queue_insert(tp, qp)
+#endif
+
+/*===========================================================================*/
+/* Module exported functions. */
+/*===========================================================================*/
+
+/**
+ * @brief Sends a message to the specified thread.
+ * @details The sender is stopped until the receiver executes a
+ * @p chMsgRelease()after receiving the message.
+ *
+ * @param[in] tp the pointer to the thread
+ * @param[in] msg the message
+ * @return The answer message from @p chMsgRelease().
+ *
+ * @api
+ */
+msg_t chMsgSend(thread_t *tp, msg_t msg) {
+ thread_t *ctp = currp;
+
+ chDbgCheck(tp != NULL);
+
+ chSysLock();
+ ctp->p_msg = msg;
+ ctp->p_u.wtobjp = &tp->p_msgqueue;
+ msg_insert(ctp, &tp->p_msgqueue);
+ if (tp->p_state == CH_STATE_WTMSG)
+ chSchReadyI(tp);
+ chSchGoSleepS(CH_STATE_SNDMSGQ);
+ msg = ctp->p_u.rdymsg;
+ chSysUnlock();
+ return msg;
+}
+
+/**
+ * @brief Suspends the thread and waits for an incoming message.
+ * @post After receiving a message 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.
+ *
+ * @return A reference to the thread carrying the message.
+ *
+ * @api
+ */
+thread_t *chMsgWait(void) {
+ thread_t *tp;
+
+ chSysLock();
+ if (!chMsgIsPendingI(currp))
+ chSchGoSleepS(CH_STATE_WTMSG);
+ tp = queue_fifo_remove(&currp->p_msgqueue);
+ tp->p_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().
+ *
+ * @param[in] tp pointer to the thread
+ * @param[in] msg message to be returned to the sender
+ *
+ * @api
+ */
+void chMsgRelease(thread_t *tp, msg_t msg) {
+
+ chSysLock();
+ chDbgAssert(tp->p_state == CH_STATE_SNDMSG, "invalid state");
+ chMsgReleaseS(tp, msg);
+ chSysUnlock();
+}
+
+#endif /* CH_CFG_USE_MESSAGES */
+
+/** @} */
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