# from http://forum.nim-lang.org/t/1188#7366

template `+`*[T](p: ptr T, off: int): ptr T =
    cast[ptr type(p[])](cast[ByteAddress](p) +% off * sizeof(p[]))
  
template `+=`*[T](p: ptr T, off: int) =
    p = p + off
  
template `-`*[T](p: ptr T, off: int): ptr T =
    cast[ptr type(p[])](cast[ByteAddress](p) -% off * sizeof(p[]))
  
template `-=`*[T](p: ptr T, off: int) =
    p = p - off

template `[]`*[T](p: ptr T, off: int): T =
    (p + off)[]

template `[]=`*[T](p: ptr T, off: int, val: T) =
    (p + off)[] = val