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);