On Tue, 23 Oct 2012 10:13:41 +0400 Cyrill Gorcunov <gorcu...@openvz.org> wrote:
> On Mon, Oct 22, 2012 at 02:51:58PM -0700, Andrew Morton wrote:
> ...
> > > + __seq_show_vmflag(VM_DONTEXPAND,"de ");
> > > + __seq_show_vmflag(VM_ACCOUNT, "ac ");
> > > + __seq_show_vmflag(VM_NORESERVE, "nr ");
> > > + __seq_show_vmflag(VM_HUGETLB, "ht ");
> > > + __seq_show_vmflag(VM_NONLINEAR, "nl ");
> > > + __seq_show_vmflag(VM_ARCH_1, "ar ");
> > > + __seq_show_vmflag(VM_DONTDUMP, "dd ");
> > > + __seq_show_vmflag(VM_MIXEDMAP, "mm ");
> > > + __seq_show_vmflag(VM_HUGEPAGE, "hg ");
> > > + __seq_show_vmflag(VM_NOHUGEPAGE,"nh ");
> ...
> >
> > This code would be much denser if we did the old
> >
> > static const char foo[] = "rdwrexshmrmw...";
> > unsigned i;
> >
> > for (i = 0; i < BITS_PER_LONG; i++) {
> > if (flags & (1 << i))
> > seq_printf("%c%c ", foo[i * 2], foo[i * 2 + 1]);
> > }
> >
> > trick. But then we'd have to remember to fix foo[] each time we
> > alter the flags, so maybe let's not do that.
>
> Yup, but not only that, this kind of trick hides associativity between
> VM_ constant and mnemonic, so on changes one would have to figure out
> which position some flag has in this foo[] array, so I vote for not
> use it :-)
Well you could do
struct {
char x[2];
} y[] = {
[CLOG2(VM_DONTEXPAND)] = { 'd', 'e' },
[CLOG2(VM_ACCOUNT)] = { 'a', 'c' },
[CLOG2(VM_NORESERVE)] = { 'n', 'r' },
};
...
for (i = 0; i < BITS_PER_LONG; i++) {
if (flags & (1 << i))
seq_printf("%c%c ", y[i][0], y[i][1]);
}
where CLOG2() is extracted from the guts of ilog2().
I'll stop now :)
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