Erste CVS-Version

firmware/message_queue.c

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+/**
+ * \file message_queue.c
+ * \brief A message queue used to exchange messages between two concurrent threads.
+ * \author Thomas Stegemann
+ * \version $Id: message_queue.c,v 1.1 2006/09/26 18:18:27 rschaten Exp $
+ *
+ * License: See documentation.
+ */
+
+#include <stdint.h>
+#include "message_queue.h"
+#include "config_message_queue_impl.h"
+
+/** Structure of the global data of the queue */
+typedef struct S_messageQueue_GlobalData {
+    messageQueue_QueuedMessage queue[messageQueue_Size]; /**< the queue itself */
+    messageQueue_SizeType begin; /**< the current start of the queue */
+    messageQueue_SizeType end; /**< the current end of the queue */
+} messageQueue_GlobalData;
+
+/** Global data of the queue */
+static volatile messageQueue_GlobalData m_data;
+
+/**
+ * Get the next entry fron the queue.
+ * \param value Number of the current entry.
+ * \return 0 if the value is larger than the queue, otherwise the next entry.
+ */
+static inline messageQueue_SizeType messageQueue_next(messageQueue_SizeType value) {
+    value++;
+    if(value >= messageQueue_Size) {
+        value= 0;
+    }
+    return value;
+}
+
+/**
+ * Initialize the queue.
+ */
+void messageQueue_init(void) {
+    m_data.begin= 0;
+    m_data.end= 0;
+}
+
+/**
+ * Clean up the queue. Currently this does nothing.
+ */
+void messageQueue_cleanup(void)
+{}
+
+/**
+ * Test if the queue is empty.
+ * \return True if it is empty, otherwise false.
+ */
+Boolean messageQueue_isEmpty(void) {
+    return boolean(m_data.begin == m_data.end);
+}
+
+/**
+ * Test if the queue is full. If it is full, new entries will overwrite the
+ * first entries.
+ * \return True if it is full, otherwise false.
+ */
+Boolean messageQueue_isFull(void) {
+    return boolean(messageQueue_next(m_data.end) == m_data.begin);
+}
+
+/**
+ * Read a message from the queue.
+ * \param pMessage Pointer to a message variable that should be set to the
+ * message.
+ * \return True if an entry could be read, otherwise false.
+ */
+Boolean messageQueue_read(messageQueue_QueuedMessage* pMessage) {
+    Boolean success= !messageQueue_isEmpty();
+    if(success) {
+        *pMessage= m_data.queue[m_data.begin];
+        m_data.begin= messageQueue_next(m_data.begin);
+    }
+    return success;
+}
+
+/**
+ * Write a message to the queue.
+ * \param message The message to append.
+ * \return True if the message could be appended, otherwise false.
+ */
+Boolean messageQueue_write(messageQueue_QueuedMessage message) {
+    Boolean success= !messageQueue_isFull();
+    if(success) {
+        m_data.queue[m_data.end]= message;
+        m_data.end= messageQueue_next(m_data.end);
+    }
+    return success;
+}