Date: Wed, 07 Feb 2007 15:04:15 +0000 From: "Bruce M. Simpson" <bms@FreeBSD.org> To: Luigi Rizzo <rizzo@icir.org> Cc: Attilio Rao <attilio@freebsd.org>, Stefan Bethke <stb@lassitu.de>, current@freebsd.org Subject: Re: C macro to find the next power of 2 ? Message-ID: <45C9EA6F.1080503@FreeBSD.org> In-Reply-To: <20070207025916.A63989@xorpc.icir.org> References: <20070207004131.A62183@xorpc.icir.org> <15241.SV0BLFJbGwk=.1170843949.squirrel@koef.zs64.net> <20070207024918.D63529@xorpc.icir.org> <3bbf2fe10702070255q58ab6c9fn2b393cfbc75a3fb@mail.gmail.com> <20070207025916.A63989@xorpc.icir.org>
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Luigi Rizzo wrote:
>> You cannot use this unless you don't rewrite as a preprocessing stub.
>>
>
> that's why i am using my version and wrote it functionally.
>
All this talk of recursively evaluated CPP macros is making my head spin.
We just want to compute LOG2(sizeof(struct foobar))+1 after all.
Ooh, but many tried and died:
http://swtch.com/gosling89ace.pdf
http://groups.google.co.uk/group/comp.lang.c/browse_thread/thread/f34a65d3fe73a6d4/0d3322283427a51a?lnk=st&q=For+loop+equivalent+with+the+preprocessor&rnum=2&hl=en#0d3322283427a51a
Go to the end of this thread, and it turns out C++ can *probably* do it
through templatization.
http://groups.google.co.uk/group/comp.lang.c/browse_thread/thread/95bfa768423adb4f/17eb99dbdf11d161?lnk=st&q=log2+preprocessor&rnum=1&hl=en#17eb99dbdf11d161
Good luck with that...
Regards,
BMS
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