On Fri, Mar 15, 2002 at 11:02:18PM -0500, Aamer Akhter wrote:
> thanks guy, i got carried away with the changes. i should have checked the
> decl of _item. i guess somebody should change the decl in README.developer it
> says that value follows length in the arglist.
I'll fix that.
> it's late friday night, so that's prob it. ;-) you still need to change the
> length in the last two calls (_val_target and _val_request) to 1.
Change the length in the calls to 1, or change the bit count in the
declaration of those fields to 16? It appears that those two fields are
part of a 16-bit field, with the reserved value being the remaining 14
bits.
> why is proto_tree_add_item() favored over boolean?
Because it fetches the value for you.
This means that you don't have to specify the same offset in the
"proto_tree_add_boolean()" call (or the "proto_tree_add_uint()" call, or
the "proto_tree_add_bytes()" call, or...) *and* in the call to fetch the
value, and you don't have the specify the same length in those two
calls, either (whether the length is specified explicitly as a number,
or implicitly in the name of the routine you're calling to fetch the
value).
Thus, for example, you don't have calls such as
proto_tree_add_uint(tree, hf_foo, tvb, offset, 2,
tvb_get_ntohl(offset));
(yes, I have fixed erroneous calls of that sort - and changed them to
"proto_tree_add_item()" calls:
proto_tree_add_item(tree, hf_foo, tvb, offset, 2, FALSE);
It also means that if "tree" is null, i.e. no protocol tree is being
built, "proto_tree_add_item()" won't even bother fetching the value,
which can save some time.
> is there any place where boolean would be favored over item.
If:
1) the value is not extracted directly from the packet data, but
is computed from data extracted from the packet
or
2) you want to use a non-standard format (note that if you just
want to, for example, use names such as "You bet!" for "true"
and "No way!" for "false", you can do that with
"proto_tree_add_item()" by giving the field the right
"true_false_string" table)
or
3) you've already fetched the item into a variable and want to
avoid having "proto_tree_add_item()" fetch it again (although
this may not actually make a performance difference)
then you would use the other "proto_tree_add" routines, such as
"proto_tree_add_uint()", "proto_tree_add_bytes()", and so on.
