[JASS] Help Reverting this trigger

[TriggerHappy]

Thanks to Acehart and Samael88 i learned the math behind base10>base62. But i'm having a bit of trouble reverting it.

private function Encode takes integer i returns string
    local string tmp
    local integer t
    local integer modulus
    if i+1 < base then
        return SubString(charMap, i-1, i)
    endif
    loop
        exitwhen i == 0
        set modulus = i - (i / base) * base
        if (modulus < 0) then
            set modulus = modulus + base
        endif
        set t = modulus
        set tmp = SubString(charMap, t-1, t) + tmp
        set i = i / base
    endloop
    return tmp
endfunction

theres the conversion .+rep to helpers.