rem: return ((uint32 *)fBlock)[block >> 5] & (1UL << (block % 32));
add: return Block(block >> 5) & (1UL << (block % 32));
context: AllocationBlock::IsUsed(uint16 block){	if (block > fNumBits)		return true;	// the block bitmap is accessed in 32-bit blocks	return ((uint32 *)fBlock)[block >> 5] & (1UL << (block % 32));}