bitarray.c

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//this class allows for creation and manipulation of arrays which hold unique IDs, and allow for bitwise-like operation over these IDs
//essentially, this extends single INT to any legth when it comes to holding and manipulating individual bits
 
const int BIT_INT_SIZE = 32;
class BitArray
{   
    static int IDToIndex(int id)
    {
        int m_NumOfItems = BitArray.IDToNumOfItems(id);
        int index   = (id - (m_NumOfItems * BIT_INT_SIZE)) - 1;
        return index;
    }
 
    static int IDToMask(int id)
    {
        int index           = BitArray.IDToIndex(id);
        int bit             = 1 << index;
        return bit;
    }

    static array<int> CreateMaskArray(int size)
    {
        int m_NumOfItems        = BitArray.IDToNumOfItems(size);
        array<int> bit_array    = new array<int>;
 
        for(int i = 0;i <= m_NumOfItems;i++)
        {
            bit_array.Insert(0);
        }
        
        return bit_array;
    }

    static int GetBitCount( array<int> bit_array )
    {
        return ( (bit_array.Count() ) * BIT_INT_SIZE );
    }

    static int IDToNumOfItems(int id)
    {
        int m_NumOfItems = id / BIT_INT_SIZE;
        if( id % BIT_INT_SIZE == 0 ) m_NumOfItems--;
        return m_NumOfItems;
    }
    
    static array<int> CreateArrayWithID(int id)
    {
        int m_NumOfItems    = BitArray.IDToNumOfItems(id);//TODO: check for too big id
        int bit             = BitArray.IDToMask(id);
        
        array<int> bit_array = new array<int>;
        
        for(int i = 0;i <= m_NumOfItems;i++)
        {
            bit_array.Insert(0);
        }
        bit_array.Set(m_NumOfItems, bit);
        return bit_array;
    }
    
    static bool IsMaskContainID(array<int> bit_array, int id)
    {
        if( BitArray.IDToNumOfItems( id ) > bit_array.Count() )
        {
            return false;
        }
        else
        {
            int index_mask      =  BitArray.IDToMask(id);
            int num_of_items    = BitArray.IDToNumOfItems(id);
            int array_mask      = bit_array.Get( num_of_items );
            
            if ( index_mask & array_mask )
            {
                return true;
            }
            else
            {
                return false;
            }
        }
    }
    
    static bool AddIDToMask(array<int> bit_array, int id)
    {
        if( BitArray.IDToNumOfItems(id) > bit_array.Count() )
        {
            return false;
        }
        else
        {
            int num_of_items    = BitArray.IDToNumOfItems(id);
            int bit             = BitArray.IDToMask(id);
            int new_mask        = bit_array.Get(num_of_items) | bit;
            bit_array.Set(num_of_items, new_mask);
            return true;
        }
    }
};