-- User Input
-- Please note the “Use GBA BIOS” option must be unselected for this script to work properly
-- Or the Disable BIOS INTRO option must be enabled
-- This program work for both Fire Red and Leaf Green without any modification

-- Start this script immediately after SRing

-- Please enter the seed from IVs to PID in the form 0x******** where the stars are the seed
targetSeed = 0x125E359C

-- Max amount of frames you are willing to wait
maxFrame = 600000

-- Number of Savestates to restore before SRing - the larger the better but no more than 65536
-- If you find that the script starts only returning "0000" then try lowering this to a number below the number of seeds it had previously tested!
looptimes = 10000


--Don’t edit anything below this unless you know what you are doing

local rshift = bit.rshift
local lshift = bit.lshift
local band = bit.band
local mdword = memory.readdwordunsigned

print("Starting... Please Wait")

--Function that does the LCRNG math
function LCRNG(s)
    local a = 0x41C6 * band(s, 0xffff) + rshift(s, 16) * 0x4E6D
    local b = 0x4E6D * band(s, 0xffff) + band(a, 0xffff) * 0x10000 + 0x6073
    return b
end

function round(num, numDecimalPlaces)
  local mult = 10^(numDecimalPlaces or 0)
  return math.floor(num * mult + 0.5) / mult
end

initialState=savestate.create()
targetHit = 0

while targetHit == 0 do
  -- Advances frame to title screen
    titleScreen = 0
    while  titleScreen < 2000 do
        emu.frameadvance()
        titleScreen = titleScreen + 1
    end

    savestate.save(initialState)

    -- Main loop for advancing frame and taking the base seed to test
    cutSceneCounter = 0
    while (cutSceneCounter < looptimes) and targetHit == 0 do
        cutSceneCounter=cutSceneCounter+1
        savestate.load(initialState)
        emu.frameadvance()
        savestate.save(initialState)

        frameCounter=1

        joypad.set(1,{A=true})
        a = 0
        while  a < 300 do
            emu.frameadvance()
            a=a+1
        end
        baseSeed=mdword(0x02020000)
        print("Testing "..cutSceneCounter.."/"..looptimes.." "..round(((cutSceneCounter / looptimes) * 100), 5).."% (Init. "..string.format("%04X", baseSeed)..")")
        PRNG=baseSeed

        currentFrame = 0
        --Calls the LCRNG math and checks for a match
        while (maxFrame > currentFrame) and targetHit == 0 and baseSeed ~= string.format("%04X", 0000) do
            PRNG=LCRNG(PRNG)

            frameCounter=frameCounter + 1
            --print(frameCounter.."/"..maxFrame)

            if targetSeed == PRNG then
                print("Finished. Your base seed is "..string.format("%04X", baseSeed).." And it happens on frame "..string.format("%04d", frameCounter)..".")
                print("Please stop the script before unpausing.")
                emu.pause()
                targetHit=1
            end
            currentFrame = currentFrame + 1

        end
    end
    --Resets game after all frames have been tested for a given SR
    if targetHit == 0 then
        print("SRing...")
        joypad.set(1,{A=true,B=true,select=true,start=true})
        emu.frameadvance()
        joypad.set(1,{A=true,B=true,select=true,start=true})
        emu.frameadvance()
        joypad.set(1,{A=true,B=true,select=true,start=true})
        emu.frameadvance()
        joypad.set(1,{A=true,B=true,select=true,start=true})
        emu.frameadvance()
        joypad.set(1,{A=true,B=true,select=true,start=true})
        emu.frameadvance()
        joypad.set(1,{A=true,B=true,select=true,start=true})
        emu.frameadvance()
        joypad.set(1,{A=true,B=true,select=true,start=true})
        emu.frameadvance()
        joypad.set(1,{A=true,B=true,select=true,start=true})
        emu.frameadvance()
        joypad.set(1,{A=true,B=true,select=true,start=true})
        emu.frameadvance()
        joypad.set(1,{A=true,B=true,select=true,start=true})
        emu.frameadvance()
        joypad.set(1,{A=true,B=true,select=true,start=true})
        emu.frameadvance()
        joypad.set(1,{A=true,B=true,select=true,start=true})
        emu.frameadvance()
        joypad.set(1,{A=true,B=true,select=true,start=true})
        emu.frameadvance()
        joypad.set(1,{A=true,B=true,select=true,start=true})
        emu.frameadvance()
    end
end