From: John Koleszar <john.koleszar@on2.com>
Date: Tue, 19 May 2009 13:31:48 GMT
Subject: Re: [PATCH 4/3] Introduce 'convert_path_to_git()'
Message-ID: <1242739908.17490.5.camel@cp-jk-linux.corp.on2.com>
In-Reply-To: <loom.20090519T120452-71@post.gmane.org>

Haven't been following this thread, so I don't know what the context is
here, but the brain teaser caught my eye.

On Tue, 2009-05-19 at 08:20 -0400, Jens Kilian wrote:
> Junio C Hamano <gitster <at> pobox.com> writes:
> > "Ugly" is not quite the word I am looking for.  "My gut feels that there
> > has to be a way to write this more cleanly, but I am frustrated that I
> > cannot come up with one" might be the word...
> 
> How about this:
> 
> #include <stdio.h>
> 

-#define MAGIC(type)  ((~(type)0 / (type)0xff) << 7)
+#define MAGIC(type)  ((type)(~(type)0 / 0xffU << 7))

> #define TEST(type) printf(#type " %llx\n", (unsigned long long)MAGIC(type))
> 
> int
> main(void)
> {
> /*TEST(unsigned char);  Doesn't work, and I'm too lazy to find out why. */
>   TEST(unsigned int);
>   TEST(unsigned long);
>   TEST(unsigned long long);
>   return 0;
> }
> 

--John