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test: hashmap - cripple the hash function by truncating the input rather than the output

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The reason for the crippled hash function is to reduce the distribution
of the hash function, do this by truncating the domain rather than the
range. This does introduce a change in behavoir as the range is no longer
contiguous, which greatly reduces collisions.

This is needed as a follow-up patch will no longer allow individual hash
functions to alter the output directly.
This commit is contained in:
Tom Gundersen 2015-10-04 01:14:41 +02:00
parent 1283d70417
commit 57217c8f2a
1 changed files with 1 additions and 1 deletions
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src/test/test-hashmap-plain.c
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@ -693,7 +693,7 @@ static void test_hashmap_get2(void) {
} }
static unsigned long crippled_hashmap_func(const void *p, const uint8_t hash_key[HASH_KEY_SIZE]) { static unsigned long crippled_hashmap_func(const void *p, const uint8_t hash_key[HASH_KEY_SIZE]) {
return trivial_hash_func(p, hash_key) & 0xff; return trivial_hash_func(INT_TO_PTR(PTR_TO_INT(p) & 0xff), hash_key);
} }
static const struct hash_ops crippled_hashmap_ops = { static const struct hash_ops crippled_hashmap_ops = {