text: what does the symbol "<<" mean in avr assembly langauge? i've just began learning the avr assembly language, and under one of the example codes there's this line:  ; set port d pins 5 and 4 direction to output ldi temp, (1<<ddd5)|(1<<ddd4) out ddrd, temp  can someone please explain to me what does (1<<ddd5) mean? thanks! =) i don't know avr, but i can say it probably is a register shift left, as that's what it is in c.    ddd5 would be a register of some length, and 1<<ddd5 would shift each bit by one, adding a zero at the end.  i'll look further and try to find a source.  -- edit:  found one.  the first source answers your question directly, the second one has a huge list of resources for you. --