What did writers, whether samurai themselves or no, have to say about the samurai code(s) of honor, if they existed, before this time? Historical fiction of the 20th century seems to depict everyone who isn't an aristocrat or samurai themselves as fearing samurai and considering them somewhere between thug and tyrant, so I imagine if such honor codes exist they might be interpreted quite differently among the lower classes.
While you wait for fresh answers from qualified experts, you may be interested in some previous responses to similar questions.
Were samurai generally honorable? with a response by /u/bigbluepanda
Was the way of Bushido ever documented in a book, if so what should I read? with another response by /u/bigbluepanda
Was the way of Bushido ever documented in a book, if so what should I read? also has a response by /u/ParallelPain