[RFC] A need for "yesno"-function? (and "cleanup" of kernel.h) (was:Re: [KJ] [RFC] A need for a "yesno"-function?)

[Richard Knutsson]

Added LKML to the Cc: to see if there is someone there who also have any 
comments...

Arnaldo Carvalho de Melo wrote:
> On 3/15/07, Richard Knutsson <ricknu-0@xxxxxxxxxxxxxx> wrote:
> > Hi
> >
> > Was just checking up the 'sparse' when I saw something like "abc"[value]
> > and thought: what about the (statement) ? "yes" : "no" I have seen in
> > the kernel.
> >
> > Ran:
> > grep -Enr "\?.*y.*\:.*n" *
> > and to my surprise, it was not so false-positive-prone and there are
> > many who does it. (Piping it to "grep yes" resulted in 153 hits) So I
> > thought, if we could standardize this and eliminate some jmp-commands
> > while doing it (the compiler should make the functions below inline), it
> > might be interesting.
> >
> > char yesno_chr(const bool value)
> > {
> >         return "ny"[value];
> > }
> >
> > char *yesno_str(const bool value)
> > {
> >         return &"no\0yes"[3 * value];
> > }
> >
> >
> > (there may be better names for them)
> > I believe this should be slightly faster. I wrote two programs (one for
> > each approach) and used 'time' while running them, and in a loop of
> > 1000,000 I found the above to be slightly faster, but the variations
> > between runs were larger.
> > So maybe it is as well to write: return value ? "yes" : "no"; but i
> > think there is a need for this kind of functions at least.
> >
> > Thoughts?
>
> The function makes sense, how you implement it? Something simple as
> this is hardly on a fast path 8)
True, but every cycled wasted... ;)
But a (condition) ? "yes" : "no" is preferable here, I guess (as it is 
more readable). The big problem is, where to put it? Seems wrong to put 
in <linux/string.h> since it appear to be a replica of userspace's 
<string.h> (otherwise, why put mem*-functions in there?).
A new file? What would it be then, "string_generic.h" maybe, and perhaps 
put in the pr_(info/debug), KERN_(WARN/...) and v?printk() (well, all 
those functions) in there. This means it will have to be included by 
<linux/kernel.h> but I think it would be a good thing to split out a few 
functions from it.

Just putting some ideas out there, any suggestions?

Richard Knutsson

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