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ghash: Simplify g_hash_table_set_shift()

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Even if we're using a prime modulo for the initial probe, our table is
power-of-two-sized, meaning we can set the mask simply by subtracting one
from the size.
This commit is contained in:
Hans Petter Jansson 2018-07-10 12:48:26 +02:00
parent 0dee62973c
commit 171f698ead
1 changed files with 5 additions and 9 deletions
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14
glib/ghash.c
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@ -297,19 +297,15 @@ static const gint prime_mod [] =
static void static void
g_hash_table_set_shift (GHashTable *hash_table, gint shift) g_hash_table_set_shift (GHashTable *hash_table, gint shift)
{ {
gint i;
guint mask = 0;
hash_table->size = 1 << shift; hash_table->size = 1 << shift;
hash_table->mod = prime_mod [shift]; hash_table->mod = prime_mod [shift];
for (i = 0; i < shift; i++) /* hash_table->size is always a power of two, so we can calculate the mask
{ * by simply subtracting 1 from it. The leading assertion ensures that
mask <<= 1; * we're really dealing with a power of two. */
mask |= 1;
}
hash_table->mask = mask; g_assert ((hash_table->size & (hash_table->size - 1)) == 0);
hash_table->mask = hash_table->size - 1;
} }
static gint static gint