Re: [Libusb-devel] [PATCH 4/4] claimed_interfaces is a long so any masks should be a long too.

[Hans de G. <hde...@re...>]

Hi,

On 02/10/2011 03:05 AM, Segher Boessenkool wrote:
>>>> The field is a long int, not a uint64_t.  Can we change that, or
>>>> is the struct exposed via the libusb API?
>>
>> libusb_device_handle is defined in libusbi.h.  It is opaque in libusb.h.
>> I
>> don't see an obvious problem with changing it.
>
> Thanks for checking.
>
> So I guess we should:
> 1) Fix all checks to be against the #define'd constant, not the size
> of the field; I think we all agree on that?

+1

> 2) Maybe change the data type of the field; not very necessary, it
> will save some space, perhaps create a tiny bit more efficient code;

I don't think we should change the type, long gives us 32 bits
guaranteed, without needing any platform specific magic.

> 3) Either or not apply Hans' patch, it's not needed anymore in
> practice if we did 1);

I actually first saw this issue with (1 << bitnr) rather then
(1L << bitnr) for a mask for a long in the kernel ages ago, where
it broke joystick buttons on 64 bit machines. Moral of the story
if you are building a mask to mask a long variable use 1L not 1.
So if we keep claimed_interfaces as a long, I would still like to
see the masks changed to 1L for correctness.

Regards,

Hans