cross-module playerdata storage

function readPDMulti(_string)
    local PDgroup, width, i={}, 0, 1
    while i<#_string do
        width=_string:byte(i+1)*0x80+_string:byte(i+2)
        PDgroup[_string:byte(i)]=_string:sub(i+3, i+2+width)
        i=i+3+width
        end
    return PDgroup
    end
function writePDMulti(PDgroup)
    local _string={}
    for id, data in pairs(PDgroup) do
        table.insert(_string, string.char(id, math.floor(#data/0x80), #data%0x80))
        table.insert(_string, data)
        end
    return table.concat(_string)
    end