saw the movie...forgot the end(spoiler)

the psychiatrist Major weiss comes into the hosiptal cell where Birdy is being held to tell Al to forget it and go home his prescence hasn't worked and the baseballs didn't bring birdy back. Then he hears Al call Birdy birdy and a fight breaks out with the hospital warders. Al grabs birdy and starts to make a run for it to escape, he gets up to the roof with birdy and is baricading the door when birdy wanders over to what appears to be the roof edge and stands for a moment then leaps like a frog out into the air to disappear down the side of the building Al shouts no birdy don't do it and runs to the edge only to find birdy 10 feet below on an adjacent building turning around and saying with a smirk "what" as if to say well what are you getting all fussed about, the film ends and the music la bamba plays. A good humoured ending? or a dark ending?