x64 Assembly and C++ Tutorial 17: Rotate Instructions

In this, the 17th, tutorial we’ll be going through four rotate instructions, ROR, ROL, RCR and RCL. These instructions perform a related operation to the shifts but there is a subtle difference. The rotate instructions don’t fill the vacant bits with 0’s or 1’s like the shift instructions. They fill the vacant bits with the bits that have been rotated out. The rotate instructions are useful becuase sometimes you might want to perform a shift but maintain the bits in the operand. If you do a shift, the data