Awesome, man! I don't know which kernel I like more, yours or VCS. You guys need to collaborate a bit and share source code. One error, I think the hammer animation needs to be sped up to about twice as fast as it is right now. It is possible to smack into a fireball or barrel just by moving towards it, even with the hammer, if the hammer happens to go up right as the enemy approaches. On the NES, this animation is very fast, making missing the barrel difficult unless it hits Mario from behind or diagonally. I believe the arcade version of the hammer animation is slower than NES but still faster than your VCS ROM, although I've haven't played the actual arcade DK (real or emulated) recently.
Also I believe you should used the Japanese screen order (1,2,3,4,1,2,3,4) instead of US (1,4,1,3,4,1,2,3,4, or however it goes), better yet use one of the difficulty switches to select the screen order.
Edited by stardust4ever, Tue Dec 24, 2013 1:30 AM.