[Tutor] [Fwd: Re: Consistant Overhead Byte Stuffing (COBS)algorithm help]

[Michael Cotherman]

> ....... is the decoding code, it does what you
> describe below. It is adding the zeros back in, that
> is the dst.append('\0')
> 
> Kent



Really??? I am a noob, but it looks like it only puts
a \0 at the end if code (the length) is less than 255,
as the if statement is out of the for loop? this would
be part of the coding algorithm, no?

In that theme of writing, here is what I would  do to
make it decode:


def UnStuffData(src,dst,len):
   if code == 0xFF:
      pass
   else:
      x = src(0)           
      for code in src:
         for i in range(1,code):
             if i == x:   
                 dst.append('\0')  
                 x = src(i)
             else:
                 dst.append(i)

   dst.pop(0)  #remove first byte
#      if code < 0xff
#          dst.append('\0') 




-mike



--- Kent Johnson <kent37 at tds.net> wrote:

> Michael Cotherman wrote:
> > def UnStuffData(src,dst,len):
> > 
> >    for code in src:
> >       for i in range(1,code):
> >           dst.append(i)
> > 
> >       if code < 0xff
> >           dst.append('\0') 
> > 
> > the above is the below code uncommented...
> >  it(and the original code) just seem to find the
> end
> > and puts a zero there...
> > 
> > I do not see the existing zeroes replaced.....
> this is
> > kinda why I wanted to start from the
> specification...
> 
> The above is the decoding code, it does what you
> describe below. It is adding the zeros back in, that
> is the dst.append('\0')
> 
> Kent
> 
> > decoding is:
> > pop the first byte of the packet off and place
> > subsequent bytes into the output until you get to
> the
> > byte pointed to by the popped byte. When you reach
> > that byte, read its value as the new 'relative'
> > pointer, and copy x00 to the output. Proceed as
> above,
> > placing bytes to the output until the relative
> pointer
> > is reached or the end of the packet occurrs.
> > 
> > I guess I need to look if I wish for this part of
> the
> > program to handle the input as one big existing
> > string, or work on it a byte at a time as it comes
> in.
> >  
> > 
> > -mike c
> 
> _______________________________________________
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> 



		
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