| // Copyright 2016 The Fuchsia Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #pragma once |
| |
| #include <stdint.h> |
| #include <string.h> |
| |
| // FNV-1a Hash |
| // |
| // http://www.isthe.com/chongo/tech/comp/fnv/index.html |
| |
| #define FNV32_PRIME (16777619) |
| #define FNV32_OFFSET_BASIS (2166136261) |
| |
| static inline uint32_t fnv1a32(const void* ptr, size_t len) { |
| uint32_t n = FNV32_OFFSET_BASIS; |
| const uint8_t* data = (const uint8_t*) ptr; |
| while (len-- > 0) { |
| n = (n ^ (*data++)) * FNV32_PRIME; |
| } |
| return n; |
| } |
| |
| #define FNV64_PRIME (1099511628211ULL) |
| #define FNV64_OFFSET_BASIS (14695981039346656037ULL) |
| |
| static inline uint64_t fnv1a64(const void* ptr, size_t len) { |
| uint64_t n = FNV64_OFFSET_BASIS; |
| const uint8_t* data = (const uint8_t*) ptr; |
| while (len-- > 0) { |
| n = (n ^ (*data++)) * FNV64_PRIME; |
| } |
| return n; |
| } |
| |
| // for bits 0..15 |
| static inline uint32_t fnv1a_tiny(uint32_t n, uint32_t bits) { |
| uint32_t hash = FNV32_OFFSET_BASIS; |
| hash = (hash ^ (n & 0xFF)) * FNV32_PRIME; n >>= 8; |
| hash = (hash ^ (n & 0xFF)) * FNV32_PRIME; n >>= 8; |
| hash = (hash ^ (n & 0xFF)) * FNV32_PRIME; n >>= 8; |
| hash = (hash ^ n) * FNV32_PRIME; |
| return ((hash >> bits) ^ hash) & ((1 << bits) - 1); |
| } |
| |
| #define fnv1a32str(str) fnv1a32(str, strlen(str)) |
| #define fnv1a64str(str) fnv1a64(str, strlen(str)) |
| |