asm {
_DIV_U64_BY_U64::
                                PUSH            RBP
                                MOV             RBP, RSP
                                XOR             RDX, RDX
                                MOV             RCX, 64
                                MOV             RAX, SF_ARG1[RBP]
                                MOV             RBX, SF_ARG2[RBP]
@@1:                    SHL1            RAX
                                RCL1            RDX
                                CMP             RBX, RDX
                                JA                      @@2
                                INC             RAX
                                SUB             RDX, RBX
@@2:                    LOOP            @@1
                                POP             RBP
                                RET1            16
}

_extern _DIV_U64_BY_U64 I64 DivU64ByU64(I64 dividend, I64 divisor);

"123456/10=%d\n", DivU64ByU64(123456, 10);