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| author | Alex AUVOLAT <alex.auvolat@ens.fr> | 2013-12-05 08:52:04 +0100 |
|---|---|---|
| committer | Alex AUVOLAT <alex.auvolat@ens.fr> | 2013-12-05 08:52:04 +0100 |
| commit | cbffb4f8d60a8516b23aae1bdf07197787ddce2c (patch) | |
| tree | 6f984a6a671866a06ebaaaf4566f4b73fe677eb0 /set_bitsets.c | |
| parent | 3ab1dd7971402fd2d76d464e4e193132b4a9eb89 (diff) | |
| download | AlgoProg-Projet-cbffb4f8d60a8516b23aae1bdf07197787ddce2c.tar.gz AlgoProg-Projet-cbffb4f8d60a8516b23aae1bdf07197787ddce2c.zip | |
Added comment
Diffstat (limited to 'set_bitsets.c')
| -rw-r--r-- | set_bitsets.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/set_bitsets.c b/set_bitsets.c index f59e61e..4ac8462 100644 --- a/set_bitsets.c +++ b/set_bitsets.c @@ -24,13 +24,13 @@ int nb_one(unsigned long long x) { //the hamming weight of x assert(SCOD==64); //1 - x = (x & 0x5555555555555555) + ((x >> 1) & 0x5555555555555555); + x = (x & 0x5555555555555555) + ((x >> 1) & 0x5555555555555555); // mask : 0101010101... //2 - x = (x & 0x3333333333333333) + ((x >> 2) & 0x3333333333333333); + x = (x & 0x3333333333333333) + ((x >> 2) & 0x3333333333333333); // mask : 001100110011... //4 - x = (x & 0x0F0F0F0F0F0F0F0F) + ((x >> 4) & 0x0F0F0F0F0F0F0F0F); + x = (x & 0x0F0F0F0F0F0F0F0F) + ((x >> 4) & 0x0F0F0F0F0F0F0F0F); // mask : 000011110000.... //8 - x = (x & 0x00FF00FF00FF00FF) + ((x >> 8) & 0x00FF00FF00FF00FF); + x = (x & 0x00FF00FF00FF00FF) + ((x >> 8) & 0x00FF00FF00FF00FF); // etc. //16 x = (x & 0x0000FFFF0000FFFF) + ((x >> 16) & 0x0000FFFF0000FFFF); //32 |