Tetris (Nintendo) Lua script

LINE21 = 0x04C8
LINENEG1 = 0x04F6

GAMESTATE = memory.readbyte(0x0048)
states = { [0] = "copyright", "moving", "locking", "checking", "clearing", "updating", "updating", "updating", "spawning", "x", "x", "x", "x", "x" }

RNG = memory.read_u16_be(0x0017)
SPAWNID = memory.readbyte(0x0019)
SPAWNCOUNT = memory.readbyte(0x001A)
--the in-game connection between the number at SPAWNID and the shape it gives
SPAWNTABLE = { [0] = 0x02, 0x07, 0x08, 0x0A, 0x0B, 0x0E, 0x12 }
--1-7 table of possible pieces
letters = { "T", "J", "Z", "O", "S", "L", "I" }
--convert spawn table number to string
names = { [0x02] = "T", [0x07] = "J", [0x08] = "Z", [0x0A] = "O", [0x0B] = "S", [0x0E] = "L", [0x12] = "I" }
--convert string to spawn table number
ids = { T = 0x02, J = 0x07, Z = 0x08, O = 0x0A, S = 0x0B, L = 0x0E, I = 0x12 }
--constants for writing sequences in easily
T = "T"; J = "J"; Z = "Z"; O = "O"; S = "S"; L = "L"; I = "I";

--transparency constants
transpercent = 75
trans = math.ceil(0xFF * transpercent/100) * 0x1000000

--color constants
lineColor = { [0x7B] = trans + 0x4240fe, [0x7C] = trans + 0x000000, [0x7D] = trans + 0x000000 }
fillColor = { [0x7B] = trans + 0xffffff, [0x7C] = trans + 0xb53220, [0x7D] = trans + 0x4240fe }

gui.defaultPixelFont("fceux")

--Keyboard states last frame and this frame
prevks = input.get()
curks = input.get()
curcheat = 0
cheatseq = {}
doubledip = false
startingSpawnCount = 0

function update()
    RNG = memory.read_u16_be(0x0017)
    SPAWNID = memory.readbyte(0x0019)
    SPAWNCOUNT = memory.readbyte(0x001A)
end

function advanceRNG()
    local temp = 0
    if (bit.check(RNG,1) ~= bit.check(RNG,9)) then temp = 1 end
    if (temp == 1) then RNG = bit.set(RNG,16) end
    RNG = bit.rshift(RNG, 1)

    return RNG
end

function pickPiece()
    --RNG = memory.read_u16_be(0x0017)
    tempRNG = RNG
    advanceRNG()
    SPAWNID = memory.readbyte(0x0019)
    SPAWNCOUNT = memory.readbyte(0x001A) + 1
    local index = bit.rshift(RNG,8) + SPAWNCOUNT
    index = index % 8
    if (index ~= 7 and SPAWNTABLE[index] ~= SPAWNID) then
        doubledip = false
        SPAWNID = SPAWNTABLE[index]
    else
        doubledip = true
        advanceRNG()
        index = bit.rshift(RNG,8)
        index = ((index % 8) + SPAWNID) % 7
        SPAWNID = SPAWNTABLE[index]
    end
    RNG = tempRNG
    return SPAWNID
end

function weLoaded(branchIndex)
    theBranch = tastudio.getbranches()[branchIndex]

    startingSpawnCount = memory.readbyte(0x001A)
    seqString = theBranch["Text"]
    cheatseq = {}

    for i = 1, string.len(seqString), 2 do
        thePiece = string.char(string.byte(seqString,i))
        --encounter illegal character in the branch name? quit out
        if (ids[thePiece] == null) then
            startingSpawnCount = 0
            return
        end
        cheatseq[#cheatseq+1] = thePiece
    end
    --Forcibly clear the greenzone
    tastudio.submitinsertframes(emu.framecount()-1,1)
    tastudio.submitdeleteframes(emu.framecount()-1,1)
    tastudio.applyinputchanges()
    tastudio.setplayback(emu.framecount()-1)


end

tastudio.onbranchload(weLoaded)

while true do
    curks = input.get()
    update()

    --you can cheat specific pieces by using the keyboard
    for i = 1, #letters do
        if (curks[letters[i]] and not prevks[letters[i]]) then
            if (curcheat == ids[letters[i]]) then curcheat = 0
            else curcheat = ids[letters[i]] end
        end
    end

    if (startingSpawnCount ~= 0) then
        advancedSpawns = SPAWNCOUNT - startingSpawnCount
        if (advancedSpawns+1 <= #cheatseq and advancedSpawns >= 0) then
            curcheat = ids[cheatseq[advancedSpawns+1]]
        else
            curcheat = 0
        end
    end

    if (curcheat ~= 0) then
        memory.writebyte(0x00BF, curcheat)
        gui.pixelText(87, 217, "CHEATING " .. names[curcheat] .. "-PIECE", "red")
    end

    for i = 5, 0, -1 do
        for j = 1, 10 do
            theBlock = memory.readbyte(LINENEG1 - (i*10) + (j-1))
            if (theBlock ~= 0xEF) then
                gui.drawRectangle(95+((j-1)*8),((6-i-1)*8)-1,8,8,lineColor[theBlock],fillColor[theBlock])
            end
        end
    end

    GAMESTATE = memory.readbyte(0x0048)
    --do not run during copyright screen
    if (GAMESTATE ~= 0) then
        color = "lightcoral"
        if (GAMESTATE == 1) then color = "lightgreen" end
        gui.pixelText(185, 190, GAMESTATE .. ": " .. states[GAMESTATE], color,"black")

        gui.pixelText(190, 146, "Next: " .. names[SPAWNID],"white","black")

        gui.drawBox(11,7,84,236,"black","black")

        for i = 0, 24 do
            nextPieceString = (emu.framecount()+i+1) .. ": " .. names[pickPiece()]
            if (doubledip) then nextPieceString = nextPieceString .. " (" .. "2" .. ")" end
            gui.pixelText(12, 8+(9*i), nextPieceString)
            advanceRNG()
        end
    end

    prevks = curks
    emu.frameadvance()
end