MASKMOVDQU, cus I'm stuck by it's instruction from the page 902 of the Intel x64 manual . I am confused on how to adjust the register sizes for this instruction. Here the documentation mentions that the default memory location is DS:DI/EDI/RDI, but the opcode includes 0x660x66? Should I replace it with 0x67 or use the REX.W prefix for EDI/RDI registers to adjust for the different sizes?