算盘：满五提珠满十进位

if lower[c] >= 5 then upper[c] = 1; lower[c] = lower[c] - 5 end

 fx-abacus

local Abacus = {}
local KEY = { COLS = 4 }

local lower, upper = {}, {}

function AB.Init()
    lower, upper = {}, {}
    for c = 1, KEY.COLS do
        lower[c] = 0
        upper[c] = 0
    end
end

function AB.AddOne()
    lower[1] = lower[1] + 1
    AB.Normalize()
end

function AB.Normalize()
    local c = 1
    while c <= KEY.COLS do
        -- 满五提上珠
        if lower[c] >= 5 and upper[c] == 0 then
            upper[c] = 1
            lower[c] = lower[c] - 5
        end
        -- 满十进位
        if lower[c] + upper[c] * 5 >= 10 then
            lower[c] = lower[c] - 10
            if upper[c] == 1 then upper[c] = 0 end
            if c < KEY.COLS then
                lower[c + 1] = lower[c + 1] + 1
                -- 进位后重新归一化当前列
                if lower[c] < 0 then lower[c] = 0 end
            end
        end
        c = c + 1
    end
end

function AB.Read()
    local v = 0
    for c = 1, KEY.COLS do
        v = v + (lower[c] + upper[c] * 5) * math.pow(10, c - 1)
    end
    return v
end

function AB.Render()
    for c = 1, KEY.COLS do
        local x = SL:GetValue("rodX", c)
        SL:DrawLowerBeads(x, lower[c])
        SL:DrawUpperBeads(x, upper[c])
    end
    SL:ShowSystemTips("读数 " .. AB.Read())
end

return AB