This is a slight improvement over Noobish Noobsicle's old patch. It's not only updated for asar and SA-1 compatibility, but it also behaves more like SMB2. Instead of automatically make you jump when you let go of down, you can now let go then jump. I also heavily commented it for learning purposes.
I like this patch but there's a couple of problems. When you die while charging the jump, it doesn't reset. But the bigger problem is when you get a game over, it could screw up the title screen demo, depending on the movements and the environment.