Wireshark · Wireshark-dev: Re: [Wireshark-dev] Help needed on value translation of dissected bits

[Jaap Keuter <jaap.keuter@xxxxxxxxx>]

Hi,

Almost, but that put bit 8 in Byte 1 at the LSB for Value B, while it's supposed 
to be the MSB.
This is a really weird encoding, not something supported by normal routines. 
Chris pointed you in the right direction how to present 'interpreted' data.

Thanks,
Jaap

John Tapparo wrote:
> Does defining it as
> { &hf_myproto_B,
>   { "B Value", "myproto.b",
>        FT_UINT16, BASE_DEC, NULL, 0xff80, NULL, HFILL
>   }
> }
>
> And then using
> proto_tree_add_item(tree, hf_myproto_B, tvb, o, 2, TRUE);
> do what you want (basically telling it that the value is little_endian)?
>
> On Wednesday 02 December 2009 11:55:55 Jarolin, Robert wrote:
> > Let me give an example:
> > Assume that you have 2 bytes to dissect that are formatted as follows:
> > - There are 2 values, A and B that are encoded into 2 Bytes
> > - Value A has a maximum size of 127 and is encoded using the lower 7
> > bits of Byte 1
> > - Value B has a maximum size of 511 and is encoded using all 8 bits in
> > Byte 2 along with bit 8 in Byte 1 representing the MSB for Value B
> >
> > Normally, I would define the dissection in the hf structure as follows:
> > { &hf_myproto_B,
> >   { "B Value", "myproto.b",
> >        FT_UINT16, BASE_DEC, NULL, 0x80ff, NULL, HFILL
> >   }
> > }