DEFAULT REL

section .rodata
string1 db "One for "
len1 equ $ - string1
string2 db ", one for me.", 0
len2 equ $ - string2

section .text
global two_fer
two_fer:
    mov rax, rdi
    mov rbx, rsi

    xor rdi, rdi

    lea rsi, [string1]
    lea rdi, [rbx]
    mov rcx, len1
    rep movsb

    xor dl, dl
    xor rcx, rcx
_label:
    cmp byte [rax], 0
    je _exit
    add rcx, 1
    jmp _label

_exit:
    mov rcx, rax
    lea rsi, [rax]
    lea rdi, [rbx + len1]
    rep movsb

    lea rsi, [string2]
    lea rdi, [rbx + len1 + rax]
    mov rcx, len2
    rep movsb

    ret