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#ifndef __NAVIGATION_H
#define __NAVIGATION_H
#include <string.h>
#include <stdlib.h>
const size_t NAVIGATION_HISTORY_SIZE = 32;
template<class T>
class CNavigation_base
{
protected:
T history[NAVIGATION_HISTORY_SIZE];
size_t historystart, historyend, historycurrent;
public:
CNavigation_base() : historystart(0),historyend(0),historycurrent(0) {}
void saveposn(T posn);
void writeposn(T posn);
bool forward(T& loc);
bool back(T& loc);
};
class CNavigation : public CNavigation_base<size_t>
{
public:
void setSaveData(unsigned char*& data, unsigned short& len, unsigned char* src, unsigned short srclen);
void putSaveData(unsigned char*& src, unsigned short& srclen);
};
template<class T>
inline void CNavigation_base<T>::saveposn(T posn)
{
history[historycurrent] = posn;
historycurrent=(historycurrent+1)%NAVIGATION_HISTORY_SIZE;
if (historycurrent==historystart)
{
historystart=(historystart+1)%NAVIGATION_HISTORY_SIZE;
}
historyend = historycurrent;
}
template<class T>
inline void CNavigation_base<T>::writeposn(T posn)
{
history[historycurrent] = posn;
}
template<class T>
inline bool CNavigation_base<T>::back(T& posn)
{
if (historycurrent!=historystart)
{
// buffer is not empty
if (historycurrent==0)
{
historycurrent=NAVIGATION_HISTORY_SIZE-1;
}
else
{
historycurrent--;
}
posn=history[historycurrent];
return true;
}
else
{
// circular buffer empty
return false;
}
}
template<class T>
inline bool CNavigation_base<T>::forward(T& posn)
{
if (historycurrent!=historyend)
{
historycurrent=(historycurrent+1)%NAVIGATION_HISTORY_SIZE;
posn = history[historycurrent];
return true;
}
else
{
return false;
}
}
#endif
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