* Peter Stuge <pe...@stuge.se> [110225 21:48]:
> Patrick Georgi wrote:
> > +int ffs(int i);
>
> Wording in my ffs(3) page suggests that int can be 64 bit. We don't
> care?
So far the only compiler I know where this could happen is MSVC. Since
we have an endless amount of GNUisms in all of our code that basically
limits us to gcc/llvm/sun compiler/intel compiler/... it will never be a
problem for us.
We might want to consider a slightly bigger but non-looping and faster
implementation
int ffs(int i)
{
int count = 1;
if (i == 0)
return 0;
if (!(i & 0xffff)) {
i >>= 16;
count += 16;
}
if (!(i & 0xff)) {
i >>= 8;
count += 8;
}
if (!(i & 0xf)) {
i >>= 4;
count += 4;
}
if (!(i & 3)) {
i >>= 2;
count += 2;
}
if (!(i & 1)) {
i >>= 1;
count += 1;
}
return count;
}
Stefan
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