From mboxrd@z Thu Jan 1 00:00:00 1970 From: mita@miraclelinux.com (Akinobu Mita) Date: Thu, 26 Jan 2006 03:36:13 +0000 Subject: [PATCH 8/12] generic hweight{32,16,8}() Message-Id: <20060126033613.GG11138@miraclelinux.com> List-Id: References: <20060125112625.GA18584@miraclelinux.com> <20060125113206.GD18584@miraclelinux.com> <20060125200250.GA26443@flint.arm.linux.org.uk> <20060125205907.GF9995@esmail.cup.hp.com> <20060126032713.GA9984@miraclelinux.com> In-Reply-To: <20060126032713.GA9984@miraclelinux.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Grant Grundler Cc: Linux Kernel Development , linux-ia64@vger.kernel.org This patch introduces the C-language equivalents of the functions below: unsigned int hweight32(unsigned int w); unsigned int hweight16(unsigned int w); unsigned int hweight8(unsigned int w); HAVE_ARCH_HWEIGHT_BITOPS is defined when the architecture has its own version of these functions. This code largely copied from: include/linux/bitops.h Index: 2.6-git/include/asm-generic/bitops.h =================================--- 2.6-git.orig/include/asm-generic/bitops.h 2006-01-25 19:14:10.000000000 +0900 +++ 2.6-git/include/asm-generic/bitops.h 2006-01-25 19:14:11.000000000 +0900 @@ -458,14 +458,38 @@ #endif /* HAVE_ARCH_FFS_BITOPS */ +#ifndef HAVE_ARCH_HWEIGHT_BITOPS + /* * hweightN: returns the hamming weight (i.e. the number * of bits set) of a N-bit word */ -#define hweight32(x) generic_hweight32(x) -#define hweight16(x) generic_hweight16(x) -#define hweight8(x) generic_hweight8(x) +static inline unsigned int hweight32(unsigned int w) +{ + unsigned int res = (w & 0x55555555) + ((w >> 1) & 0x55555555); + res = (res & 0x33333333) + ((res >> 2) & 0x33333333); + res = (res & 0x0F0F0F0F) + ((res >> 4) & 0x0F0F0F0F); + res = (res & 0x00FF00FF) + ((res >> 8) & 0x00FF00FF); + return (res & 0x0000FFFF) + ((res >> 16) & 0x0000FFFF); +} + +static inline unsigned int hweight16(unsigned int w) +{ + unsigned int res = (w & 0x5555) + ((w >> 1) & 0x5555); + res = (res & 0x3333) + ((res >> 2) & 0x3333); + res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F); + return (res & 0x00FF) + ((res >> 8) & 0x00FF); +} + +static inline unsigned int hweight8(unsigned int w) +{ + unsigned int res = (w & 0x55) + ((w >> 1) & 0x55); + res = (res & 0x33) + ((res >> 2) & 0x33); + return (res & 0x0F) + ((res >> 4) & 0x0F); +} + +#endif /* HAVE_ARCH_HWEIGHT_BITOPS */ #endif /* __KERNEL__ */