From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1C52A10E050 for ; Thu, 23 Feb 2023 10:53:29 +0000 (UTC) From: =?UTF-8?q?Zbigniew=20Kempczy=C5=84ski?= To: igt-dev@lists.freedesktop.org Date: Thu, 23 Feb 2023 11:53:19 +0100 Message-Id: <20230223105321.49048-1-zbigniew.kempczynski@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: [igt-dev] [PATCH i-g-t 1/3] lib/igt_map: Add 32-bit and 64-bit hash helper functions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: igt-dev-bounces@lists.freedesktop.org Sender: "igt-dev" List-ID: Creating igt_map requires hashing and comparing function. Common case is using 32-bit (like fd, etc.) or 64-bit keys (offsets) so adding such helpers reduces code duplication. Signed-off-by: Zbigniew Kempczyński --- lib/igt_map.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++ lib/igt_map.h | 5 +++++ 2 files changed, 64 insertions(+) diff --git a/lib/igt_map.c b/lib/igt_map.c index da8713a186..ffa1e6beaa 100644 --- a/lib/igt_map.c +++ b/lib/igt_map.c @@ -196,6 +196,7 @@ igt_map_search(struct igt_map *map, const void *key) * Returns: map entry or %NULL if no entry is found. * Note that the data pointer may be modified by the user. */ + struct igt_map_entry * igt_map_search_entry(struct igt_map *map, const void *key) { @@ -500,3 +501,61 @@ igt_map_random_entry(struct igt_map *map, return NULL; } + +#define GOLDEN_RATIO_PRIME_32 0x9e370001UL +/** + * igt_map_hash_32: + * @key: pointer to 32-bit key + * + * Function is hashing function for 32-bit keys. Key is pointer to 32-bit + * value so it must be dereferenced. + */ +uint32_t igt_map_hash_32(const void *key) +{ + uint32_t hash = *(uint32_t *)key; + + hash = hash * GOLDEN_RATIO_PRIME_32; + return hash; +} + +/** + * igt_map_equal_32: + * @key1: pointer to first 32-bit key + * @key2: pointer to second 32-bit key + * + * Function compares 32-bit keys. + */ +int igt_map_equal_32(const void *key1, const void *key2) +{ + return *(uint32_t *)key1 == *(uint32_t *)key2; +} + +/* 2^63 + 2^61 - 2^57 + 2^54 - 2^51 - 2^18 + 1 */ +#define GOLDEN_RATIO_PRIME_64 0x9e37fffffffc0001ULL +/** + * igt_map_hash_64: + * @key: pointer to 64-bit key + * + * Function is hashing function for 64-bit keys. Key is pointer to 64-bit + * value so it must be dereferenced. + */ +uint32_t igt_map_hash_64(const void *key) +{ + uint64_t hash = *(uint64_t *)key; + + hash = hash * GOLDEN_RATIO_PRIME_64; + /* High bits are more random, so use them. */ + return hash >> 32; +} + +/** + * igt_map_equal_64: + * @key1: pointer to first 64-bit key + * @key2: pointer to second 64-bit key + * + * Function compares 64-bit keys. + */ +int igt_map_equal_64(const void *key1, const void *key2) +{ + return *(uint64_t *)key1 == *(uint64_t *)key2; +} diff --git a/lib/igt_map.h b/lib/igt_map.h index cadcd6e35f..a0fbd1419f 100644 --- a/lib/igt_map.h +++ b/lib/igt_map.h @@ -171,4 +171,9 @@ igt_map_insert_pre_hashed(struct igt_map *map, uint32_t hash, const void *key, void *data); +uint32_t igt_map_hash_32(const void *key); +int igt_map_equal_32(const void *key1, const void *key2); +uint32_t igt_map_hash_64(const void *key); +int igt_map_equal_64(const void *key1, const void *key2); + #endif -- 2.34.1