CircularBuffer.h

// -*- c++ -*-
#ifndef __CIRCULARBUFFER_H__
#define __CIRCULARBUFFER_H__

// storage
#include "storage/RawValue.h"

class CircularBuffer
{
public:

    CircularBuffer();
 
    void allocate(DbrType type, DbrCount count, size_t num);

    DbrType getDbrType() const
    { return type; }
   
    DbrCount getDbrCount() const
    { return count; }
    
    size_t getCapacity() const
    {   return max_index-1; }

    size_t getCount() const;

    void reset();
    
    size_t getOverwrites() const
    {   return overwrites; }

    RawValue::Data *getNextElement();
    
    void addRawValue(const RawValue::Data *raw_value);

    const RawValue::Data *getRawValue(size_t i) const;
    
    const RawValue::Data *removeRawValue();

  void dump() const;
    
private:

  CircularBuffer(const CircularBuffer &); // not impl.
  CircularBuffer & operator = (const CircularBuffer &); // not impl.

  RawValue::Data    *getElement(size_t i) const;

  DbrType  type;    // dbr_time_xx
  DbrCount count;   // array size of type
  MemoryBuffer<char> buffer;  // the buffer
  size_t   element_size;// == RawValue::getSize (_type, _count)
  size_t   max_index;   // max. number of elements in buffer
  size_t   head;        // index of current element
  size_t   tail;        // before(!) last element, _tail==_head: empty
  size_t   overwrites;  // # of elements we had to drop
};

#endif //__CIRCULARBUFFER_H__