Use of data types

[Ben Dooks]

On Tue, Jan 19, 2010 at 08:57:03PM +0900, Khushhua Mogambo wrote:
> On Mon, Jan 18, 2010 at 10:58 PM, Sergei Shtylyov
> <sshtylyov at ru.mvista.com> wrote:
> > Hello.
> >
> > Matthias Kaehlcke wrote:
> >
> >>>> Hi
> >>>>  I starting to port Linux kernel to my companies new ARM based
> >>>> SoC and development board.
> >>>>
> >>>> Some of the regs is 16bits wide and some is 32bits width. I ask if
> >>>> my using u16 and u32 in place of 'unsigned short' and 'unsigned int'
> >>>> in the whole porting would be acceptable or not?
> >>>>
> >>>> In different wording, using only u16 and u32 always is considered good
> >>>> quality or bad?
> >>>>
> >>>
> >>> I prefer using u32 over int.  Still more if your register space isn't
> >>> uniform.
> >>>
> >>
> >> ditto
> >>
> >> how about using the C99 types uint32_t, ... in the kernel?
> >
> >  They are actually used in some places but this is generally frowned upon.
> > They are for userspace.
> >
> > WBR, Sergei
> 
> from thread, i understand that u32 is encouraged whenever we have reason. I m
> going to use u8,16,32 heavily.

It can depend on where it is being used, passing u8 and u16 around from
function to function can cost as the compiler tends to output code
to restrict the range of the registers' contents, thus u32 can end up
being a better choice.

-- 
Ben

Q:      What's a light-year?
A:      One-third less calories than a regular year.