Re: [dtn-interest] new i-d on sdnvs

[Wesley Eddy <[e-mail]>]

On Mon, Apr 24, 2006 at 05:28:43PM +0200, Gerardo Izquierdo wrote:
> I think the python Source Code about SNDV is  a bit incorrect

You're right, thanks.  I think maybe the draft should state that the code
is just for demonstration purposes, and that (for example) the C++ SDNV
code in the DTN2 implementation should more similar to what people actually
use in production.  That said, it is also important the the code be correct
in this document.
 
> sdnv_encode does not encode well the value 0 (0x00), it returns an empty
> string
> 
> I haven't never programmed in python, but I think we should add a line just
> before the
> return r
> 
> 
> if type(n) == type(1) and n = 0:
>    r = chr (0x00)
>

Instead of doing this, I changed the looping construct to always execute
at least once:
    done = False
    while not done:
      # encode lowest 7 bits from n
      newbits = n & 0x7F
      n = n>>7
      r = chr(newbits + flag) + r
      if flag == 0:
        flag = 0x80
      if n == 0:
        done = True


> also, there is no reference to the optional parameter slen in sdnv_decode
> but in the parameter declaration.

The line:
    elif i == len(s)-1:
should be:
    elif i == len(s)-1 or i > slen:

These will be fixed in the next update.  Thanks.

-Wes

-- 
Wesley M. Eddy
Verizon Federal Network Systems