96 lines
2.5 KiB
C
96 lines
2.5 KiB
C
/**
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* \file message_queue.c
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* \brief A message queue used to exchange messages between two concurrent threads.
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* \author Thomas Stegemann
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* \version $Id: message_queue.c,v 1.2 2006/09/29 22:30:03 rschaten Exp $
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*
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* License: See documentation.
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*/
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#include <stdint.h>
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#include "message_queue.h"
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#include "config_message_queue_impl.h"
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/** Structure of the global data of the queue */
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typedef struct S_messageQueue_GlobalData {
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messageQueue_QueuedMessage queue[messageQueue_Size]; /**< the data elements of the queue */
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messageQueue_SizeType begin; /**< the current start of the queue */
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messageQueue_SizeType end; /**< the current end of the queue, behind the last element */
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} messageQueue_GlobalData;
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/** Global data of the queue */
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static volatile messageQueue_GlobalData m_data;
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/**
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* increments an messageQueue index
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* \param value position within the messageQueue
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* \return the following position within the messageQueue
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*/
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static inline messageQueue_SizeType messageQueue_next(messageQueue_SizeType value) {
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value++;
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if(value >= messageQueue_Size) {
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/* messageQueue is used circular */
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value= 0;
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}
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return value;
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}
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/**
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* Initialize the queue.
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*/
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void messageQueue_init(void) {
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m_data.begin= 0;
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m_data.end= 0;
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}
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/**
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* Clean up the queue. Currently this does nothing.
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*/
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void messageQueue_cleanup(void)
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{}
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/**
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* Test if the queue is empty.
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* \return True if it is empty, otherwise false.
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*/
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Boolean messageQueue_isEmpty(void) {
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return boolean(m_data.begin == m_data.end);
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}
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/**
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* Test if the queue is full.
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* \return True if it is full, otherwise false.
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*/
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Boolean messageQueue_isFull(void) {
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return boolean(messageQueue_next(m_data.end) == m_data.begin);
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}
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/**
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* Read a message from the queue.
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* \param pMessage Pointer to a message variable that should be set to the
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* message.
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* \return True if an entry could be read, otherwise false.
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*/
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Boolean messageQueue_read(messageQueue_QueuedMessage* pMessage) {
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Boolean success= !messageQueue_isEmpty();
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if(success) {
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*pMessage= m_data.queue[m_data.begin];
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m_data.begin= messageQueue_next(m_data.begin);
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}
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return success;
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}
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/**
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* Write a message to the queue.
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* \param message The message to append.
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* \return True if the message could be appended, otherwise false.
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*/
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Boolean messageQueue_write(messageQueue_QueuedMessage message) {
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Boolean success= !messageQueue_isFull();
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if(success) {
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m_data.queue[m_data.end]= message;
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m_data.end= messageQueue_next(m_data.end);
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}
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return success;
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}
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