forked from 0ad/0ad
96 lines
2.3 KiB
C++
96 lines
2.3 KiB
C++
/* Copyright (C) 2021 Wildfire Games.
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include "precompiled.h"
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#include "lib/fnv_hash.h"
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// FNV1-A hash - good for strings.
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// if len = 0 (default), treat buf as a C-string;
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// otherwise, hash <len> bytes of buf.
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u32 fnv_hash(const void* buf, size_t len)
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{
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u32 h = 0x811c9dc5u;
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// give distinct values for different length 0 buffers.
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// value taken from FNV; it has no special significance.
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const u8* p = (const u8*)buf;
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// expected case: string
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if(!len)
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{
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while(*p)
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{
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h ^= *p++;
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h *= 0x01000193u;
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}
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}
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else
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{
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size_t bytes_left = len;
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while(bytes_left != 0)
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{
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h ^= *p++;
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h *= 0x01000193u;
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bytes_left--;
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}
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}
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return h;
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}
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// FNV1-A hash - good for strings.
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// if len = 0 (default), treat buf as a C-string;
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// otherwise, hash <len> bytes of buf.
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u64 fnv_hash64(const void* buf, size_t len)
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{
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u64 h = 0xCBF29CE484222325ull;
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// give distinct values for different length 0 buffers.
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// value taken from FNV; it has no special significance.
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const u8* p = (const u8*)buf;
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// expected case: string
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if(!len)
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{
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while(*p)
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{
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h ^= *p++;
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h *= 0x100000001B3ull;
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}
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}
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else
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{
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size_t bytes_left = len;
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while(bytes_left != 0)
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{
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h ^= *p++;
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h *= 0x100000001B3ull;
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bytes_left--;
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}
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}
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return h;
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}
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