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author | Jens Axboe <jens.axboe@oracle.com> | 2010-05-21 23:27:26 +0400 |
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committer | Jens Axboe <jens.axboe@oracle.com> | 2010-05-21 23:27:26 +0400 |
commit | ee9a3607fb03e804ddf624544105f4e34260c380 (patch) | |
tree | ce41b6e0fa10982a306f6c142a92dbf3c9961284 /tools/perf/util/hweight.c | |
parent | b492e95be0ae672922f4734acf3f5d35c30be948 (diff) | |
parent | d515e86e639890b33a09390d062b0831664f04a2 (diff) | |
download | linux-ee9a3607fb03e804ddf624544105f4e34260c380.tar.xz |
Merge branch 'master' into for-2.6.35
Conflicts:
fs/ext3/fsync.c
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'tools/perf/util/hweight.c')
-rw-r--r-- | tools/perf/util/hweight.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/tools/perf/util/hweight.c b/tools/perf/util/hweight.c new file mode 100644 index 000000000000..5c1d0d099f0d --- /dev/null +++ b/tools/perf/util/hweight.c @@ -0,0 +1,31 @@ +#include <linux/bitops.h> + +/** + * hweightN - returns the hamming weight of a N-bit word + * @x: the word to weigh + * + * The Hamming Weight of a number is the total number of bits set in it. + */ + +unsigned int hweight32(unsigned int w) +{ + unsigned int res = w - ((w >> 1) & 0x55555555); + res = (res & 0x33333333) + ((res >> 2) & 0x33333333); + res = (res + (res >> 4)) & 0x0F0F0F0F; + res = res + (res >> 8); + return (res + (res >> 16)) & 0x000000FF; +} + +unsigned long hweight64(__u64 w) +{ +#if BITS_PER_LONG == 32 + return hweight32((unsigned int)(w >> 32)) + hweight32((unsigned int)w); +#elif BITS_PER_LONG == 64 + __u64 res = w - ((w >> 1) & 0x5555555555555555ul); + res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul); + res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful; + res = res + (res >> 8); + res = res + (res >> 16); + return (res + (res >> 32)) & 0x00000000000000FFul; +#endif +} |