0011nnnnmmmm0101
op1 ← ZeroExtend32(SignExtend32(Rm));
op2 ← ZeroExtend32(SignExtend32(Rn));
mac ← op2 × op1;
macl ← mac;
mach ← mac >> 32;
MACL ← ZeroExtend32(macl);
MACH ← ZeroExtend32(mach);