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18a40587ea
Problem: - Hash functions can be `constexpr`, but are not. Solution: - Change `inline` keyword to `constexpr`. - Add `static_assert` tests to ensure the hash functions work in a `constexpr` context.
75 lines
2.3 KiB
C++
75 lines
2.3 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include "Types.h"
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constexpr unsigned int_hash(u32 key)
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{
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key += ~(key << 15);
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key ^= (key >> 10);
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key += (key << 3);
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key ^= (key >> 6);
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key += ~(key << 11);
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key ^= (key >> 16);
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return key;
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}
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constexpr unsigned double_hash(u32 key)
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{
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key = ~key + (key >> 23);
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key ^= (key << 12);
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key ^= (key >> 7);
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key ^= (key << 2);
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key ^= (key >> 20);
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return key;
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}
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constexpr unsigned pair_int_hash(u32 key1, u32 key2)
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{
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return int_hash((int_hash(key1) * 209) ^ (int_hash(key2 * 413)));
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}
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constexpr unsigned u64_hash(u64 key)
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{
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u32 first = key & 0xFFFFFFFF;
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u32 last = key >> 32;
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return pair_int_hash(first, last);
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}
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constexpr unsigned ptr_hash(FlatPtr ptr)
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{
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if constexpr (sizeof(ptr) == 8)
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return u64_hash(ptr);
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else
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return int_hash(ptr);
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}
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inline unsigned ptr_hash(const void* ptr)
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{
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return ptr_hash(FlatPtr(ptr));
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}
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