diff options
| -rw-r--r-- | include/ouroboros/hash.h | 3 | ||||
| -rw-r--r-- | src/lib/hash.c | 13 | ||||
| -rw-r--r-- | src/lib/tests/hash_test.c | 37 |
3 files changed, 53 insertions, 0 deletions
diff --git a/include/ouroboros/hash.h b/include/ouroboros/hash.h index 17ab98ac..c6609ffc 100644 --- a/include/ouroboros/hash.h +++ b/include/ouroboros/hash.h @@ -89,4 +89,7 @@ void str_hash(enum hash_algo algo, void * dst, const char * str); +/* Non-cryptographic finalizer for hashing an integer key to a table index. */ +uint64_t hash_mix64(uint64_t key); + #endif /* OUROBOROS_LIB_HASH_H */ diff --git a/src/lib/hash.c b/src/lib/hash.c index 9b26a552..903474df 100644 --- a/src/lib/hash.c +++ b/src/lib/hash.c @@ -74,8 +74,10 @@ uint16_t hash_len(enum hash_algo algo) { if (algo == HASH_CRC8) return CRC8_HASH_LEN; + if (algo == HASH_CRC16) return CRC16_HASH_LEN; + if (algo == HASH_CRC64) return CRC64_HASH_LEN; #ifdef HAVE_LIBGCRYPT @@ -164,3 +166,14 @@ void str_hash(enum hash_algo algo, { return mem_hash(algo, dst, (const uint8_t *) str, strlen(str)); } + +uint64_t hash_mix64(uint64_t key) +{ + key ^= key >> 33; + key *= 0xff51afd7ed558ccdULL; + key ^= key >> 33; + key *= 0xc4ceb9fe1a85ec53ULL; + key ^= key >> 33; + + return key; +} diff --git a/src/lib/tests/hash_test.c b/src/lib/tests/hash_test.c index 451d3c25..a2ba62cc 100644 --- a/src/lib/tests/hash_test.c +++ b/src/lib/tests/hash_test.c @@ -39,6 +39,11 @@ struct vec_entry { char * out; }; +struct mix_entry { + uint64_t in; + uint64_t out; +}; + static int test_crc8(void) { int ret = 0; @@ -288,6 +293,36 @@ static int test_sha3(void) return ret; } +static int test_mix64(void) +{ + int ret = 0; + + struct mix_entry vec [] = { + { 0x0000000000000000ULL, 0x0000000000000000ULL }, + { 0x123456789abcdefeULL, 0xb1943cfea4f78f08ULL } + }; + + size_t n = sizeof(vec) / sizeof(vec[0]); + size_t i; + + TEST_START(); + + for (i = 0; i < n; i++) { + uint64_t res = hash_mix64(vec[i].in); + + if (res != vec[i].out) { + printf("Mix failed %016llx != %016llx.\n", + (unsigned long long) res, + (unsigned long long) vec[i].out); + ret |= -1; + } + } + + TEST_END(ret); + + return ret; +} + int hash_test(int argc, char ** argv) { @@ -308,5 +343,7 @@ int hash_test(int argc, ret |= test_sha3(); + ret |= test_mix64(); + return ret; } |