82 lines
1.9 KiB
C
82 lines
1.9 KiB
C
/*
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* This software is licensed under the terms of the MIT License.
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* See COPYING for further information.
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* ---
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* Copyright (c) 2011-2019, Lukas Weber <laochailan@web.de>.
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* Copyright (c) 2012-2019, Andrei Alexeyev <akari@taisei-project.org>.
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*/
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#pragma once
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#include "taisei.h"
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/*
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* hash_t
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*
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* Type of the hash values.
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*/
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typedef uint32_t hash_t;
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#define HT_HASH_LIVE_BIT ((hash_t)(1) << (sizeof(hash_t) * CHAR_BIT - 1))
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typedef hash_t ht_size_t;
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// for hashsets
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struct ht_empty { };
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#define HT_EMPTY ((struct ht_empty) {})
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/*
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* htutil_hashfunc_uint32
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*
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* Hash function for 32-bit integers
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* NOTE: assuming hash_t stays uint32_t, this function has no collisions.
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*/
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INLINE hash_t htutil_hashfunc_uint32(uint32_t x) {
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x = ((x >> 16) ^ x) * 0x45d9f3b;
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x = ((x >> 16) ^ x) * 0x45d9f3b;
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x = (x >> 16) ^ x;
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return (hash_t)x;
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}
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/*
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* htutil_hashfunc_uint64
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*
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* Hash function for 64-bit integers.
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*/
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INLINE hash_t htutil_hashfunc_uint64(uint64_t x) {
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x = (x ^ (x >> 30)) * UINT64_C(0xbf58476d1ce4e5b9);
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x = (x ^ (x >> 27)) * UINT64_C(0x94d049bb133111eb);
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x = x ^ (x >> 31);
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return (hash_t)x;
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}
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/*
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* htutil_hashfunc_string
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*
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* Hash function for null-terminated strings.
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*/
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INLINE uint32_t htutil_hashfunc_string(const char *str) {
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// FNV1a hash
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//
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// Not looking for '\0' in the for loop because apparently compilers optimize this better.
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// Both GCC and clang can fold this entire function into a constant with a constant str.
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// GCC fails that if strlen is not used.
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uint32_t hash = 0x811c9dc5;
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uint32_t prime = 0x1000193;
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size_t len = strlen(str);
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for(int i = 0; i < len; ++i) {
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uint8_t value = str[i];
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hash = hash ^ value;
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hash *= prime;
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}
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return hash;
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}
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// Import public declarations for the predefined hashtable types.
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#define HT_DECL
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#include "hashtable_predefs.inc.h"
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// NOTE: For the hashtable API, see hashtable.inc.h
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// NOTE: For type-generic wrappers around the API, see hashtable_predefs.inc.h
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