Fire Emblem - Sealed Sword - Bug Finder

local dis

function nextrng(r1, r2, r3)
    return AND(XOR(SHIFT(r3, 5), SHIFT(r2, -11), SHIFT(r1, -1), SHIFT(r2, 15)),0xFFFF)
end

function rngsim(n)
    local rngbase=0x03000000
    local result = { memory.readword(rngbase+4), memory.readword(rngbase+2), memory.readword(rngbase+0) }
    for i = 4, n do
        result[i] = nextrng(result[i-3],result[i-2],result[i-1])
    end
    return result
end

function printstats(n)
    if n == 255 then
        n = "---"
    end
    return n
end

function get100()
    dis = nil
    for i = 4, 500, 1 do
        if rngs[i] >= 65534 then
            dis = i-3
            break
        end
    end
end

while true do
    local nsim = 20
    rngs = rngsim(500)
    for i = 1, nsim do
        gui.text(228, 8*(i-1), string.format("%3d", rngs[i]/655))
    end
    if dis ~= nil then
        gui.text(4,4,"Distance: " .. dis)
        if dis == 1 then
            gui.text(174,(dis+2)*8,"-->","red")
        else
            gui.text(212,(dis+2)*8,"-->","red")
        end
    end
    gui.text(206,0,"RNG1:")
    gui.text(206,8,"RNG2:")
    gui.text(206,16,"RNG3:")
    gui.text(190,24,"Next RNs:")
    get100()
    emu.frameadvance()
end