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;
 }
 }
};