genesis-3d_engine/Engine/foundation/util/ringbuffer.h

#pragma once
/****************************************************************************
Copyright (c) 2008, Radon Labs GmbH
Copyright (c) 2011-2013,WebJet Business Division,CYOU
 
http://www.genesis-3d.com.cn

Permission is hereby granted, free of charge, to any person obtaining a copy
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The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
****************************************************************************/

#include "core/types.h"

//------------------------------------------------------------------------------
namespace Util
{
template <class TYPE> class RingBuffer
{
public:
    /// default constructor
    RingBuffer();
    /// constructor with size
    RingBuffer(SizeT capacity);
    /// copy constructor
    RingBuffer(const RingBuffer<TYPE>& rhs);
    /// destructor
    ~RingBuffer();
    /// assignment operator
    void operator=(const RingBuffer<TYPE>& rhs);
    /// index operator
    TYPE& operator[](IndexT index) const;
    
    /// set capacity (clear previous content)
    void SetCapacity(SizeT newCapacity);
    /// get capacity
    SizeT Capacity() const;
    /// get number of elements in ring buffer
    SizeT Size() const;
    /// add an element to the ring buffer
    void Add(const TYPE& elm);
    /// return true if ring buffer is empty
    bool IsEmpty() const;
    /// reset ring buffer, just reset the head/base indices without calling destructors
    void Reset();
    /// return reference to first element
    TYPE& Front() const;
    /// return reference to last element
    TYPE& Back() const;
    /// return all values as array
    Array<TYPE> AsArray() const;    
    /// get real linear underlying buffer
    TYPE* GetBuffer();
    /// get real linear underlying buffer
    const TYPE* GetBuffer() const;

private:
    /// allocate element buffer
    void Allocate(SizeT capacity);
    /// delete content
    void Delete();
    /// copy content
    void Copy(const RingBuffer<TYPE>& src);

    SizeT capacity;
    SizeT size;
    IndexT baseIndex;
    IndexT headIndex;
    TYPE* elements;
};

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
RingBuffer<TYPE>::Allocate(SizeT c)
{
    #if NEBULA3_BOUNDSCHECKS
    n_assert(0 == this->elements);
    n_assert(c > 0);
    #endif
    this->capacity = c;
    this->size = 0;
    this->baseIndex = 0;
    this->headIndex = 0;
    this->elements = n_new_array(TYPE, c);
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
RingBuffer<TYPE>::Delete()
{
    this->capacity = 0;
    this->size = 0;
    this->baseIndex = 0;
    this->headIndex = 0;
    if (0 != this->elements)
    {
        n_delete_array(this->elements);
        this->elements = 0;
    }
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
RingBuffer<TYPE>::Copy(const RingBuffer<TYPE>& rhs)
{
    #if NEBULA3_BOUNDSCHECKS
    n_assert(0 == this->elements);
    #endif
    this->Allocate(rhs.capacity);
    this->size = rhs.size;
    this->baseIndex = rhs.baseIndex;
    this->headIndex = rhs.headIndex;
    IndexT i;
    for (i = 0; i < rhs.Size(); i++)
    {
        (*this)[i] = rhs[i];
    }
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE>
RingBuffer<TYPE>::RingBuffer() :
    capacity(0),
    size(0),
    baseIndex(0),
    headIndex(0),
    elements(0)
{
    // empty
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE>
RingBuffer<TYPE>::RingBuffer(SizeT c) :
    elements(0)
{
    this->Allocate(c);
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE>
RingBuffer<TYPE>::RingBuffer(const RingBuffer<TYPE>& rhs) :
    elements(0)
{
    this->Copy(rhs);
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE>
RingBuffer<TYPE>::~RingBuffer()
{
    this->Delete();
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
RingBuffer<TYPE>::operator=(const RingBuffer<TYPE>& rhs)
{
    this->Delete();
    this->Copy(rhs);
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> TYPE&
RingBuffer<TYPE>::operator[](IndexT index) const
{
    #if NEBULA3_BOUNDSCHECKS
    n_assert(this->elements && (index < this->size));
    #endif
    IndexT absIndex = index + this->baseIndex;
    if (absIndex >= this->capacity)
    {
        // wrap-around
        absIndex -= this->capacity;
    }
    return this->elements[absIndex];
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> TYPE&
RingBuffer<TYPE>::Front() const
{
    return (*this)[0];
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> TYPE&
RingBuffer<TYPE>::Back() const
{
    #if NEBULA3_BOUNDSCHECKS
    n_assert(this->size > 0);
    #endif
    return (*this)[this->size - 1];
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> bool
RingBuffer<TYPE>::IsEmpty() const
{
    return (0 == this->size);
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
RingBuffer<TYPE>::Reset()
{
    this->size = 0;
    this->baseIndex = 0;
    this->headIndex = 0;
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
RingBuffer<TYPE>::SetCapacity(SizeT newCapacity)
{
    this->Delete();
    this->Allocate(newCapacity);
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> SizeT
RingBuffer<TYPE>::Capacity() const
{
    return this->capacity;
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> SizeT
RingBuffer<TYPE>::Size() const
{
    return this->size;
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> void
RingBuffer<TYPE>::Add(const TYPE& elm)
{
    #if NEBULA3_BOUNDSCHECKS
    n_assert(0 != this->elements);
    #endif

    // write new element
    this->elements[this->headIndex++] = elm;

    // check if head index should wrap around
    if (this->headIndex >= this->capacity)
    {
        this->headIndex = 0;
    }

    // if we are full, we need to advance the base index
    if (this->size == this->capacity)
    {
        this->baseIndex++;
        if (this->baseIndex >= this->capacity)
        {
            // wraparound base index
            this->baseIndex = 0;
        }
    }
    else
    {
        // not full yet, increment size member
        this->size++;
    }
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE> Array<TYPE>
RingBuffer<TYPE>::AsArray() const
{
    Array<TYPE> result(this->size, 0);
    IndexT i;
    for (i = 0; i < this->size; i++)
    {
        result.Append((*this)[i]);
    }
    return result;
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE>
TYPE* 
RingBuffer<TYPE>::GetBuffer()
{
    n_assert(this->elements);
    return this->elements;
}

//------------------------------------------------------------------------------
/**
*/
template<class TYPE>
const TYPE* 
RingBuffer<TYPE>::GetBuffer() const
{
    n_assert(this->elements);
    return this->elements;
}

} // namespace Util
//------------------------------------------------------------------------------