On Fri, 2018-06-29 at 10:30 +0300, Kalle Valo wrote:
> Pkshih <pkshih@xxxxxxxxxxx> writes:
>
> > On Tue, 2018-05-29 at 08:18 +0300, Kalle Valo wrote:
> >> <pkshih@xxxxxxxxxxx> writes:
> >>
> >
> > Because C2H data is little endian order, the struct will look like
> > struct foo {
> > #ifdef __LITTLE_ENDIAN
> > u8 bar:4;
> > u8 koo:4;
> > #else
> > u8 koo:4;
> > u8 bar:4;
> > #endif
> > }
>
> With u8 you don't need endian check, right? I would assume that with
> both little and big endian bar and koo would be in the same place.
I think u8 with bitfield would be different between little and big endian
machines.
> > Is this a linux convention?
>
> Earlier bitfields were disliked but nowadays they seem to be have become
> more acceptable. But I think the preferred way still is something like
> this (using u32 and 16 bit fields):
>
> struct foo {
> __le32 koobar;
> }
>
> #define RTLWIFI_BAR_MASK GENMASK(15, 0)
> #define RTLWIFI_KOO_MASK GENMASK(31, 16)
>
> bar = FIELD_GET(RTLWIFI_BAR_MASK, __le32_to_cpu(foo->koobar));
> koo = FIELD_GET(RTLWIFI_KOO_MASK, __le32_to_cpu(foo->koobar));
>
> Of course there can be other good ways to do the same, others can chime
> in about those, but this is how I would do it.
>
I will rewrite this part by your suggestions.
Thanks
PK
