renamed circularFifo

slsReceiverSoftware/include/CircularFifo.h

@@ -0,0 +1,149 @@
+#pragma once
+/* CircularFifo.h 
+* Code & platform dependent issues with it was originally
+* published at http://www.kjellkod.cc/threadsafecircularqueue
+* 2009-11-02
+* @author Kjell Hedstr<74>m, hedstrom@kjellkod.cc
+* modified by the sls detetor group
+* */
+
+#include <semaphore.h>
+#include <vector>
+#include <iostream>
+
+/** Circular Fifo (a.k.a. Circular Buffer)
+* Thread safe for one reader, and one writer */
+template<typename Element>
+class CircularFifo {
+public:
+
+   CircularFifo(unsigned int Size) : tail(0), head(0){
+	   Capacity = Size + 1;
+	   array.resize(Capacity);
+	   sem_init(&data_mutex,0,0);
+	   sem_init(&free_mutex,0,Size);
+   }
+   virtual ~CircularFifo() {
+       sem_destroy(&data_mutex);
+	   sem_destroy(&free_mutex);
+   }
+
+   bool push(Element*& item_, bool no_block=false);
+   bool pop(Element*& item_, bool no_block=false);
+
+   bool isEmpty() const;
+   bool isFull() const;
+
+   int getDataValue() const;
+   int getFreeValue() const;
+
+private:
+   std::vector <Element*> array;
+   unsigned int tail; // input index
+   unsigned int head; // output index
+   unsigned int Capacity;
+   mutable sem_t data_mutex;
+   mutable sem_t free_mutex;
+   unsigned int increment(unsigned int idx_) const;
+};
+
+template<typename Element>
+int CircularFifo<Element>::getDataValue() const
+{
+   int value;
+   sem_getvalue(&data_mutex, &value);
+   return value;
+}
+
+template<typename Element>
+int CircularFifo<Element>::getFreeValue() const
+{
+    int value;
+    sem_getvalue(&free_mutex, &value);
+    return value;
+}
+
+
+/** Producer only: Adds item to the circular queue.
+* If queue is full at 'push' operation no update/overwrite
+* will happen, it is up to the caller to handle this case
+*
+* \param item_ copy by reference the input item
+* \param no_block if true, return immediately if fifo is full
+* \return whether operation was successful or not */
+template<typename Element>
+bool CircularFifo<Element>::push(Element*& item_, bool no_block)
+{
+    // check for fifo full
+    if (no_block && isFull())
+        return false;
+
+    sem_wait(&free_mutex);
+    array[tail] = item_;
+    tail = increment(tail);
+    sem_post(&data_mutex);
+    return true;
+}
+
+/** Consumer only: Removes and returns item from the queue
+* If queue is empty at 'pop' operation no retrieve will happen
+* It is up to the caller to handle this case
+*
+* \param item_ return by reference the wanted item
+* \param no_block if true, return immediately if fifo is full
+* \return whether operation was successful or not */
+template<typename Element>
+bool CircularFifo<Element>::pop(Element*& item_, bool no_block)
+{
+    // check for fifo empty
+    if (no_block && isEmpty())
+        return false;
+
+   sem_wait(&data_mutex);
+   item_ = array[head];
+   head = increment(head);
+   sem_post(&free_mutex);
+   return true;
+}
+
+/** Useful for testinng and Consumer check of status
+  * Remember that the 'empty' status can change quickly
+  * as the Procuder adds more items.
+  *
+  * \return true if circular buffer is empty */
+template<typename Element>
+bool CircularFifo<Element>::isEmpty() const
+{
+    return (getDataValue() == 0);
+}
+
+/** Useful for testing and Producer check of status
+  * Remember that the 'full' status can change quickly
+  * as the Consumer catches up.
+  *
+  * \return true if circular buffer is full.  */
+template<typename Element>
+bool CircularFifo<Element>::isFull() const
+{
+    return (getFreeValue() == 0);
+}
+
+/** Increment helper function for index of the circular queue
+* index is inremented or wrapped
+*
+*  \param idx_ the index to the incremented/wrapped
+*  \return new value for the index */
+template<typename Element>
+unsigned int CircularFifo<Element>::increment(unsigned int idx_) const
+{
+   // increment or wrap
+   // =================
+   //    index++;
+   //    if(index == array.lenght) -> index = 0;
+   //
+   //or as written below:
+   //    index = (index+1) % array.length
+   idx_ = (idx_+1) % Capacity;
+   return idx_;
+}
+