Double Dragon 2: The Revenge flying knee timing trainer

readme

The script is written for fceux emulator. 

It simply reads the memory addresses of the game that seem to determine if a flying knee can be performed in that frame.
The script shows the state by drawing a large red or green box just below the game area.

Logically the box drawing may be one frame off, but I'm not sensitive enough to feel that. 
If you are, change those 0x06 and 0x07 values to your liking.

Much credit to https://www.youtube.com/watch?v=2nI6EuzJ-sw which provided the address of the knee timer.

dd2_knee.lua

while (true) do
	-- Highest byte denotes looking left or right, would be nice
	-- to drop that, but lua 5.1 doesn't seem to have bitwise operators
	local CROUCHING_LEFT = 0x06;
	local CROUCHING_RIGHT = 0x86;
	local sprite = memory.readbyte(0x00c7);
	local kneetimer = memory.readbyte(0x0055);
	gui.box(60, 186, 200, 190, "red");
	if (sprite == CROUCHING_LEFT or sprite == CROUCHING_RIGHT) then
		if (kneetimer == 0x06 or kneetimer == 0x07) then
			gui.box(60, 186, 200, 190, "green");
		end;
	end;
	emu.frameadvance();
end;