Andy,
> What I'm trying to tell is about consistency of style.
I completely agree with all you wrote, those are all good suggestions.
But you started your reasoning with:
> So, imagine if we have two bitfields in some register, one with one
> bit and the other with two.
We are not looking at a hardware register here. Rather, I am trying to
bring at least _some_ order to an arbitrary set of values that the
vendor assumed would be fun to scatter around a dozen of firmware
functions. Some hardware features are controlled by setting a specific
bit in the value being passed to a function; in other cases entire
integers are taken into account; in yet another case *two* bits in a
value control state. There is no reason or order to be found here.
In the case of OP_* constants, perhaps the simplest thing to do would be
to define them as integers, not bitfields. But that still results in a
mess:
#define OP_GET 0x2
#define OP_GET_CAPS 0x0
#define OP_GET_EVENTS 0x1
#define OP_GET_EXT 0x4
#define OP_SET 0x1
#define OP_SET_EXT 0x5
or:
#define OP_GET_CAPS 0x0
#define OP_GET_EVENTS 0x1
#define OP_SET 0x1
#define OP_GET 0x2
#define OP_GET_EXT 0x4
#define OP_SET_EXT 0x5
Even worse, what am I supposed to do with crap like radio LED control,
where 0x20 (bit 5) is passed in one argument to select the desired
feature and 0x20 or 0 is passed as another argument to select the
desired state of that feature? How do I name and define constants that
I can subsequently use in call_fext_func() invocations to spare the
reader the need to learn the hard way that this:
return call_fext_func(device, FUNC_FLAGS, 0x5, RADIO_LED_ON, 0x0);
is actually supposed to turn the radio LED *off*?
This is the best I could come up with:
#define FEAT_RADIO_LED BIT(5)
#define STATE_RADIO_LED_OFF (0 << 0)
#define STATE_RADIO_LED_ON BIT(5)
Yes, it is ugly. But the resulting call is (IMHO) a lot more clear than
the original one:
return fext_flags(device, OP_SET_EXT, FEAT_RADIO_LED, STATE_RADIO_LED_OFF);
All of the above is why I was inclined to just use alphabetic ordering
for all constants defined in fujitsu-laptop. This approach brings at
least _some_ consistency to this mess (which only the vendor is to blame
for, of course). If you would rather have me take a different approach,
I am all ears.
--
Best regards,
Michał Kępień
