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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;
}
//! Creates an array which will be able to accomodate 'size' number of unique IDs
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;
}
//! Returns number of bits this array can hold
static int GetBitCount( array<int> bit_array )
{
return ( (bit_array.Count() ) * BIT_INT_SIZE );
}
//! Returns number of INTs required to hold this ID minus 1(ie for 32, the result is 0, for 33, the result is 1)
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;
}
}
}; |