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authorJim Meyering <jim@meyering.net>2007-09-25 21:27:14 +0200
committerJim Meyering <jim@meyering.net>2007-09-25 21:27:14 +0200
commit0359c2e1cad84b1c5008c622afd47cd10db2f55d (patch)
tree090678be2875b9e3ccb4f8d9c29d0e6c42fb8312
parente2a6cbca3ba9f2a198c741a1fec6f27c6cb198d8 (diff)
downloadcoreutils-0359c2e1cad84b1c5008c622afd47cd10db2f55d.tar.xz
Use XOR, not OR to combine bits.
* gl/lib/hash-triple.c (triple_hash): Use XOR (^), not OR (|), to combine the bits from hashing the name and those of the inode number. Add a few comments and remove out-of-context ones.
-rw-r--r--ChangeLog7
-rw-r--r--gl/lib/hash-triple.c15
2 files changed, 10 insertions, 12 deletions
diff --git a/ChangeLog b/ChangeLog
index 8fb325414..228d26df6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2007-09-25 Jim Meyering <jim@meyering.net>
+
+ Use XOR, not OR to combine bits.
+ * gl/lib/hash-triple.c (triple_hash): Use XOR (^), not OR (|), to
+ combine the bits from hashing the name and those of the inode number.
+ Add a few comments and remove out-of-context ones.
+
2007-09-24 Jim Meyering <jim@meyering.net>
* NEWS: The recent rm-diagnostic fix also affects cross-partition "mv".
diff --git a/gl/lib/hash-triple.c b/gl/lib/hash-triple.c
index dfe2a592d..74b9de80c 100644
--- a/gl/lib/hash-triple.c
+++ b/gl/lib/hash-triple.c
@@ -8,27 +8,18 @@
#include "same.h"
#include "same-inode.h"
-/* Hash an F_triple. */
+/* Hash an F_triple, and *do* consider the file name. */
size_t
triple_hash (void const *x, size_t table_size)
{
struct F_triple const *p = x;
-
- /* Also take the name into account, so that when moving N hard links to the
- same file (all listed on the command line) all into the same directory,
- we don't experience any N^2 behavior. */
- /* FIXME-maybe: is it worth the overhead of doing this
- just to avoid N^2 in such an unusual case? N would have
- to be very large to make the N^2 factor noticable, and
- one would probably encounter a limit on the length of
- a command line before it became a problem. */
size_t tmp = hash_pjw (p->name, table_size);
/* Ignoring the device number here should be fine. */
- return (tmp | p->st_ino) % table_size;
+ return (tmp ^ p->st_ino) % table_size;
}
-/* Hash an F_triple. */
+/* Hash an F_triple, without considering the file name. */
size_t
triple_hash_no_name (void const *x, size_t table_size)
{