Bit Twiddling Tricks From Game Engine Gems 2

BitTwiddling.h

// https://twitter.com/EricLengyel/status/1620683606216835073

int clearLowestSetBit(int x)
{
  return x & (x-1);
}

int setLowestUnsetBit(int x)
{
  return x | (x+1); 
}

int setAllBitsToRightOfLowestSetBit(int x)
{
  return x | (x-1);
}

int clearAllBitsToRightOfLowestUnsetBit(int x)
{
  return x & (x+1);
}

int extractLowestSetBit(int x)
{
  return x & -x;
}

int extractLowestUnsetBit(int x)
{
  return ~x & (x+1);
}

int createMaskForBitsOtherThanLowestSetBit(int x)
{
  return ~x | (x-1);
}

int createMaskForBitsOtherThanLowestUnsetBit(int x)
{
  return x | ~(x+1);
}

int createMaskForBitsLeftOfAndIncludingLowestSetBit(int x)
{
  return x | -x;
}

int createMaskForBitsLeftOfLowestSetBit(int x)
{
  return x ^ -x;
}

int createMaskForBitsLeftOfAndIncludingLowestUnsetBit(int x)
{
  return ~x | (x+1);
}

int createMaskForBitsLeftOfLowestUnsetBit(int x)
{
  return ~x ^ (x+1);
}

int createMaskForBitRightOfAndIncludingLowestSetBit(int x)
{
  return x ^ (x-1);
}

int createMaskForBitRightOfLowestSetBit(int x)
{
  return ~x & (x-1);
}

int createMaskForBitRightOfAndIncludingLowestUnsetBit(int x)
{
  return x ^ (x+1);
}

int createMaskForBitRightOfLowestUnsetBit(int x)
{
  return x & (~x-1);
}