function os.pullEventRaw( sFilter )
    return coroutine.yield( sFilter )
end

function os.pullEvent( sFilter )
    local eventData = table.pack( os.pullEventRaw( sFilter ) )
    if eventData[1] == "terminate" then
        error( "Terminated", 0 )
    end
    return table.unpack( eventData, 1, eventData.n )
end

-- Install globals
function sleep( nTime )
    if nTime ~= nil and type( nTime ) ~= "number" then
        error( "bad argument #1 (expected number, got " .. type( nTime ) .. ")", 2 )
    end
    local timer = os.startTimer( nTime or 0 )
    repeat
        local sEvent, param = os.pullEvent( "timer" )
    until param == timer
end

local tAPIsLoading = {}
function os.loadAPI( _sPath )
    if type( _sPath ) ~= "string" then
        error( "bad argument #1 (expected string, got " .. type( _sPath ) .. ")", 2 )
    end
    local sName = fs.getName( _sPath )
    if sName:sub(-4) == ".lua" then
        sName = sName:sub(1,-5)
    end
    if tAPIsLoading[sName] == true then
        printError( "API "..sName.." is already being loaded" )
        return false
    end
    tAPIsLoading[sName] = true

    local tEnv = {}
    setmetatable( tEnv, { __index = _G } )
    local fnAPI, err = loadfile( _sPath, tEnv )
    if fnAPI then
        local ok, err = pcall( fnAPI )
        if not ok then
            printError( err )
            tAPIsLoading[sName] = nil
            return false
        end
    else
        printError( err )
        tAPIsLoading[sName] = nil
        return false
    end

    local tAPI = {}
    for k,v in pairs( tEnv ) do
        if k ~= "_ENV" then
            tAPI[k] =  v
        end
    end

    _G[sName] = tAPI
    tAPIsLoading[sName] = nil
    return true
end

os.loadAPI("/rom/textutils")
os.loadAPI("/rom/peripheral")

loadfile = function( _sFile, _tEnv )
    if type( _sFile ) ~= "string" then
        error( "bad argument #1 (expected string, got " .. type( _sFile ) .. ")", 2 )
    end
    if _tEnv ~= nil and type( _tEnv ) ~= "table" then
        error( "bad argument #2 (expected table, got " .. type( _tEnv ) .. ")", 2 )
    end
    local file = fs.open( _sFile, "r" )
    if file then
        local func, err = loadstring( file.readAll(), fs.getName( _sFile ), "t", _tEnv )
        file.close()
        return func, err
    end
    return nil, "File not found"
end

dofile = function( _sFile )
    if type( _sFile ) ~= "string" then
        error( "bad argument #1 (expected string, got " .. type( _sFile ) .. ")", 2 )
    end
    local fnFile, e = loadfile( _sFile, _G )
    if fnFile then
        return fnFile()
    else
        error( e, 2 )
    end
end