From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ulrich Eckhardt Date: Fri, 03 Feb 2006 08:31:42 +0000 Subject: Re: [patch 14/44] generic hweight{64,32,16,8}() Message-Id: <200602030931.43686.eckhardt@satorlaser.com> List-Id: References: <20060201090224.536581000@localhost.localdomain> <20060201090325.905071000@localhost.localdomain> In-Reply-To: <20060201090325.905071000@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Akinobu Mita Cc: linux-kernel@vger.kernel.org, Richard Henderson , Ivan Kokshaysky , Russell King , Ian Molton , dev-etrax@axis.com, David Howells , Yoshinori Sato , Linus Torvalds , linux-ia64@vger.kernel.org, Hirokazu Takata , linux-m68k@vger.kernel.org, Greg Ungerer , linux-mips@linux-mips.org, parisc-linux@parisc-linux.org, linuxppc-dev@ozlabs.org, linux390@de.ibm.com, linuxsh-dev@lists.sourceforge.net, linuxsh-shmedia-dev@lists.sourceforge.net, sparclinux@vger.kernel.org, ultralinux@vger.kernel.org, Miles Bader , Andi Kleen , Chris Zankel On Wednesday 01 February 2006 10:02, Akinobu Mita wrote: > unsigned int hweight32(unsigned int w); > unsigned int hweight16(unsigned int w); > unsigned int hweight8(unsigned int w); > unsigned long hweight64(__u64 w); IMHO, this should use explicitly sized integers like __u8, __u16 etc, unless there are stringent reasons like better register use - which is hard to tell for generic C code. Also, why on earth is the returntype for hweight64 a long? > +static inline unsigned int hweight32(unsigned int w) > +{ > + unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555); > + res = (res & 0x33333333) + ((res >> 2) & 0x33333333); [...] Why not use unsigned constants here? > +static inline unsigned long hweight64(__u64 w) > +{ [..] > + u64 res; > + res = (w & 0x5555555555555555ul) + ((w >> 1) & 0x5555555555555555ul); Why not use initialisation here, too? just my 2c Uli