cmp bl, 0xaa \n jz shellcode \n cmp bl, 0xbb \n jz xordecode jmp notdecode
compare the content of bl register with the end character, 0xaa. if they arer equal go to shellcodelable, else compare the content of bl register with the character 0xbb that is the placeholder for xor. if they are equal go to _xordecode label. else go to _notdecode label.