bios.lua

--[[
Improved Bootloader BIOS for OpenComputers Lua
(C) The Puzzlemaker 2019
--]]
local init
do
  local cinvoke = component.invoke
  local function binvoke(address, method, ...)
    local result = table.pack(pcall(cinvoke, address, method, ...))
    if not result[1] then
      return nil, result[2]
    else
      return table.unpack(result, 2, result.n)
    end
  end

  local eeprom = component.list("eeprom")()
  computer.getBootAddress = function()
    return binvoke(eeprom, "getData")
  end
  computer.setBootAddress = function(address)
    return binvoke(eeprom, "setData", address)
  end

  do
    local screen = component.list("screen")()
    gpu = component.list("gpu")()
    if gpu and screen then
      binvoke(gpu, "bind", screen)
    else
      error("GPU required", 0)
    end
  end

  local function tablelength(T)
    local count = 0
    for _ in pairs(T) do count = count + 1 end
    return count
  end

  local function tryLoadFrom(address)
    local handle, reason = binvoke(address, "open", "/init.lua")
    if not handle then
      return nil, reason
    end
    local buffer = ""
    repeat
      local data, reason = binvoke(address, "read", handle, math.huge)
      if not data and reason then
        return nil, reason
      end
      buffer = buffer .. (data or "")
    until not data
    binvoke(address, "close", handle)
    return load(buffer, "=init")
  end
  local reason
  local validAddresses = {}
  if computer.getBootAddress() ~= "" then
    table.insert(validAddresses, computer.getBootAddress())
  end
  for address in component.list("filesystem") do
    if address ~= computer.getBootAddress() then
      table.insert(validAddresses, address)
    end
  end

  local function tryGetLabel(address)
    if binvoke(address, "getLabel") ~= nil and binvoke(address, "getLabel") ~= "" then
      return binvoke(address, "getLabel")
    else
      return "NO LABEL"
    end
  end

  local function printAddrs()
    for k,address in ipairs(validAddresses) do
      binvoke(component.list("gpu")(), "set", 1, k, k .. ": [" .. tryGetLabel(address) .. "] " .. address)
    end
  end
  printAddrs()
  while true do
    local evt, addr, char, code, pN = computer.pullSignal()
    if evt == "key_up" then
      local num = tonumber(unicode.char(char))
      if num ~= nil then
        if num >= 1 and num <= tablelength(validAddresses) then
          binvoke(component.list("gpu")(), "set", 1, num, num.. ": [TRYING] [" .. tryGetLabel(validAddresses[num]) .. "] " .. validAddresses[num])
          init, reason = tryLoadFrom(validAddresses[num])
          if init then
            binvoke(component.list("gpu")(), "set", 1, num, num.. ": [BOOTING] [" .. tryGetLabel(validAddresses[num]) .. "] " .. validAddresses[num])
            computer.setBootAddress(validAddresses[num])
            break
          else
            computer.beep(500, 0.2)
            binvoke(component.list("gpu")(), "set", 1, num, num.. ": [INVALID] [" .. tryGetLabel(validAddresses[num]) .. "] " .. validAddresses[num])
          end
        end
      end
    end
  end
end
computer.beep(1000, 0.2)
init()