On Mon, 12 Apr 2010 22:37:00 -0400, Steven Schveighoffer
<schvei...@yahoo.com> wrote:
Jérôme M. Berger Wrote:
Steven Schveighoffer wrote:
> Fails for test case:
>
> minA = 4, maxA = 4, minB = 4, maxB = 6 (outputs 7, accurate result is
6).
>
Nope, outputs 6. Note that I've run an exhaustive search for all
combinations in the [0, 63] range, so if there are mistakes they
have to be outside that range...
I'll have to double check, I thought I copied your code verbatim (I did
switch around the arguments to be minA, maxA, minB, maxB to fit my test
harness, and I changed the uint_32_t to uint). I'll check tomorrow at
work where the computer I used to test is.
I confirm, with the updated highbit, your solution works.
Also, inspired by your solution (and using your highbit function, which is
very neat BTW) I came up with a one-liner. Enjoy :)
uint maxor(uint mina, uint maxa, uint minb, uint maxb)
{
return maxa | maxb | ((1 << highbit(((1 << (max(highbit(mina ^ maxa),
highbit(minb ^ maxb)) + 1)) - 1) & maxa & maxb)) - 1);
}
Anyone want to do the equivalent minor? I've spent way too much time on
this :)
-Steve
