Re: [RFA] New bitflags type and eflags on i386/x86-64

[Michal Ludvig <mludvig at suse dot cz>]

Daniel Jacobowitz wrote:
> On Mon, Apr 22, 2002 at 06:08:09PM +0200, Michal Ludvig wrote:
> 
>>Daniel Jacobowitz wrote:
> unpack_long returns LONGEST.  Why not have a flagword bigger than that?

Where would you store it? And what type would you use for it?

>>>I would prefer if you instead added
>>>support to c-valprint.c for something like Pascal's TYPE_CODE_SET (see
>>>p-valprint.c) and used that.  It should be exactly what you're looking
>>>for.  Basically, you create an enum describing the bit position (not
>>>mask) for each flag, and then call create_set_type with that type as
>>>the domain_type.

I still don't understand these "nested" types :-(

Is this a correct procedure?
- create an ENUM type
- set its nfields to number of bits of my flagword.
- allocate space for its fields[bits] and fill all fields with propper
   position of the bit and its name.
- call create_set_type with the just created enum

Is that all?

Than I have some questions:
- What should be in the 'length' field of ENUM and what in lenght field 
of SET?
- Should I set ENUM's entries (fields) for all bits in the flagword (eg. 
32) or is it enough to set only used ones and ignore the rest when 
printing it (I'd prefer this approach).

BTW How do I extract a value of the variable using unpack_long()? I 
tried to call it both with type and elttype but always got a wrong 
result. Can it be because of wrong lenght fields in these types?

>>I was about to use TYPE_CODE_SET, but I don't know how to add names to 
>>its elements. With FLAGS they are written during initialization. Also 
>>FLAGS is more simple than SET appears to be. Unfortunately I used pascal 
>>too long ago to remember how the set type behaves like...
> 
> I described that in my message.  If you create an enum first,
> everything should just work.  I don't see the virtue in adding another
> type here.

Actually, I do. Type FLAG perfectly and cleanly does what it was ceated 
for and is self-describing. Using SET seems to be less synoptical. Also 
SET is used so rarely in gdb that it isn't a defact standard for such 
things.

Michal Ludvig
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