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12 Feb 2007

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RingBuffer.hpp

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 * ViTooKi                                                              *
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 * title:       RingBuffer.hpp                                          *
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 *  REVISION HISTORY:                                                   *
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 ***********************************************************************/
#ifndef VITOOKI_PS_RINGBUFFER_HPP
#define VITOOKI_PS_RINGBUFFER_HPP

template<class T> class RingBuffer{
        T invalid;
        T* data;
        int* keys;
        int startPos;
        int endPos;
        int size;
public:
        RingBuffer(int siz) {
                size=siz;
                data=new T[size];
                keys=new int[size];
                startPos=endPos=0;
                // set to NULL
                memset(data,0,size*sizeof(T));
        };

        ~RingBuffer() {
                delete[] keys;delete[] data;
        };

        void put(T& elem,int key){
                if(startPos==0 && 0==endPos) {
                        // this happens exactly only once! During the first insert.
                        // in all other cases endPos will be always larger than startPos
                        data[startPos]=elem;
                        keys[startPos]=key;
                        endPos++;
                }
                else {
                        assert(endPos-startPos<=size); // > should never happen
                        if(endPos-startPos==size) {
                                // we are full, overwrite object
                                startPos++;
                        }
                        // now insert the element       
                        data[endPos%size]=elem;
                        keys[endPos%size]=key;
                        endPos++;
                }
        };
        
        T get(int key, bool* found) {                   
                assert(found);
                // endpos always points to the next insert pos
                for(int i=startPos;i<endPos;i++) {
                        if(keys[i%size]==key) {
                                keys[i%size]=-1;
                                *found=true;
                                return data[i%size];
                        }
                }
                *found=false;
                return invalid;
        };
};      

#endif

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