Hi,
See this blurb in README.developer
bitmask
-------
If the field is a bitfield, then the bitmask is the mask which will
leave only the bits needed to make the field when ANDed with a value.
The proto_tree routines will calculate 'bitshift' automatically
from 'bitmask', by finding the rightmost set bit in the bitmask.
If the field is not a bitfield, then bitmask should be set to 0.
This is a snippet of code I use:
proto_tree_add_item(option_tree, hf_option_gain, tvb, offset, 1, FALSE);
Where the gain is stored in the high nibble. To get at that value I've
defined the field like this:
static hf_register_info hf[] =
{
{
&hf_option_gain,
{
"Gain", "option.gain",
FT_UINT8, BASE_DEC,
VALS(option_gain_vals), 0xF0,
"", HFILL
}
}
Thanx,
Jaap
On Mon, 6 Nov 2006 Andrew.Martin@xxxxxxxxxxxxxxxxxxxxxx wrote:
> Hi,
>
> I'm developing a dissector, now within a packet header there are 2
> bytes, 5 bits relate to flags and 3 bits refer to the message. I've
> managed to seperate the flags into their individual bits, but I need all
> three of the remaining bits.
>
> How do I do that?
>
> Cheers
>
>
>
