nrg_field.h

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/*
  LibNRG - Networking for Real-time Games
  
  Copyright (C) 2012-2014 Alex Baines <alex@abaines.me.uk>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#ifndef NRG_FIELD_H
#define NRG_FIELD_H
#include "nrg_core.h"
#include "nrg_packet.h"
#include "nrg_codec.h"
#include "nrg_util.h"
#include "nrg_interp.h"
#include <bitset>

namespace nrg {

class FieldContainer;

class FieldBase {
public:
    FieldBase(FieldContainer* container);
    
    FieldBase(const FieldBase& copy);
    
    FieldBase& operator=(const FieldBase& copy);
    
    virtual size_t readFromPacket(Packet& p) = 0;
    
    virtual size_t writeToPacket(Packet& p) const = 0;
    
    virtual void shiftData() = 0;
    
    virtual ~FieldBase(){}

    virtual bool wasUpdated() const;
    
    virtual void setUpdated(bool updated);
    
    FieldBase* getNextField() const;
    
    void setNextField(FieldBase* f);
protected:
    FieldContainer* container;
    FieldBase* next;
    bool updated;
};

struct FieldContainer {
    FieldContainer();
    
    FieldContainer(const FieldContainer& copy);
    
    FieldContainer& operator=(const FieldContainer& copy);

    FieldBase* getFirstField() const;
    
    size_t getNumFields() const;
    
    virtual void markUpdated(bool b) = 0;
    virtual double getInterpTimer() const { return 1.0; }
    void addField(FieldBase* f);
private:
    FieldBase* field_head;
    size_t num_fields;
};

template<typename T, class Cdc = nrg::Codec<T> >
class Field : private FieldBase {
public:
    /* Standard Constructor */
    Field(FieldContainer* c) : FieldBase(c), data(), data_next(){}
    
    /* Constructor with specified initial value \p t */
    Field(FieldContainer* c, const T& t) : FieldBase(c), data(t), data_next(t){}

    virtual size_t readFromPacket(Packet& p){
        return Cdc().decode(p, data_next);
    }

    virtual size_t writeToPacket(Packet& p) const {
        return Cdc().encode(p, data);
    }

    virtual void shiftData(){
        data = data_next;
    }

    void set(const T& other){
        *this = other;
    }

    Field& operator=(const T& other){
        if(data != other){
            data = data_next = other;
            this->setUpdated(true);
        }
        return *this;
    }
    
    T get() const {
        return data_next;
    }

    template<class F>
    T getInterp(const F& func) const {
        return func(data, data_next, this->container->getInterpTimer());
    }

    T getInterp() const {
        return lerp<T>()(data, data_next, this->container->getInterpTimer());
    }
private:
    T data, data_next;
};

template<typename T, size_t N>
class Field<T[N]> : private FieldBase {
public:
    Field(FieldContainer* c) : FieldBase(c), data(){
        updated_indices.set();
    }
    Field(FieldContainer* c, const T (&t)[N]) : FieldBase(c), data(t){
        updated_indices.set();
    }

    virtual size_t readFromPacket(Packet& p){
        index_t count;
        p.read<index_t>(count);
        size_t uic = count + 1;
        
        if(uic * (sizeof(index_t) + sizeof(T)) > N * sizeof(T)){
            for(size_t i = 0; i < N; ++i){
                p.read<T>(data_next[i]);
            }
            return sizeof(index_t) + N * sizeof(T);
        } else {
            for(size_t i = 0; i < uic; ++i){
                index_t k;
                p.read<index_t>(k);
                if(k < N){
                    p.read<T>(data_next[k]);
                } else { // out of bounds for some reason, don't crash.
                    p.seek(SEEK_CUR, sizeof(T));
                }
            }
            return sizeof(index_t) + (uic * (sizeof(index_t) + sizeof(T)));
        }
    }

    virtual size_t writeToPacket(Packet& p) const {
        size_t uic = updated_indices.count();
        p.write<index_t>(uic-1);
        
        if(uic * (sizeof(index_t) + sizeof(T)) > N * sizeof(T)){
            for(size_t i = 0; i < N; ++i){
                p.write<T>(data[i]);
            }
            return sizeof(index_t) + (N * sizeof(T));
        } else {
            for(size_t i = 0; i < N; ++i){
                if(updated_indices[i]){
                    p.write<index_t>(i);
                    p.write<T>(data[i]);
                }
            }
            return sizeof(index_t) + (uic * (sizeof(index_t) + sizeof(T)));
        }
    }

    virtual void shiftData(){
        memcpy(data, data_next, N * sizeof(T));
    }

    virtual void setUpdated(bool updated){
        FieldBase::setUpdated(updated);
        if(!updated) updated_indices.reset();
    }

    void set(size_t index, const T& other){
        if(data[index] != other){
            data[index] = other;
            updated_indices.set(index);
            FieldBase::setUpdated(true);
        }
    }

    Field& operator=(const T (&other)[N]){
        data = other;
        FieldBase::setUpdated(true);
        return *this;
    }
    
    T get(size_t index) const {
        return data_next[index];
    }
    
    template<class F>
    T getInterp(size_t index, const F& func) const {
        return func(data[index], data_next[index], this->container->getInterpTimer());
    }

    T getInterp(size_t index) const {
        return lerp<T>()(data[index], data_next[index], this->container->getInterpTimer());
    }
private:
    T data[N], data_next[N];
    std::bitset<N> updated_indices;
    typedef typename detail::size2type<detail::min_sizeof<N-1>::val>::type index_t;
};

}

#endif