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/* Copyright (C) 2010 Wildfire Games.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/*
* Fowler/Noll/Vo string hash
*/
#include "precompiled.h"
// FNV1-A hash - good for strings.
// if len = 0 (default), treat buf as a C-string;
// otherwise, hash <len> bytes of buf.
u32 fnv_hash(const void* buf, size_t len)
{
u32 h = 0x811c9dc5u;
// give distinct values for different length 0 buffers.
// value taken from FNV; it has no special significance.
const u8* p = (const u8*)buf;
// expected case: string
if(!len)
{
while(*p)
{
h ^= *p++;
h *= 0x01000193u;
}
}
else
{
size_t bytes_left = len;
while(bytes_left != 0)
{
h ^= *p++;
h *= 0x01000193u;
bytes_left--;
}
}
return h;
}
// FNV1-A hash - good for strings.
// if len = 0 (default), treat buf as a C-string;
// otherwise, hash <len> bytes of buf.
u64 fnv_hash64(const void* buf, size_t len)
{
u64 h = 0xCBF29CE484222325ull;
// give distinct values for different length 0 buffers.
// value taken from FNV; it has no special significance.
const u8* p = (const u8*)buf;
// expected case: string
if(!len)
{
while(*p)
{
h ^= *p++;
h *= 0x100000001B3ull;
}
}
else
{
size_t bytes_left = len;
while(bytes_left != 0)
{
h ^= *p++;
h *= 0x100000001B3ull;
bytes_left--;
}
}
return h;
}
// special version for strings: first converts to lowercase
// (useful for comparing mixed-case filenames).
// note: still need <len>, e.g. to support non-0-terminated strings
u32 fnv_lc_hash(const char* str, size_t len)
{
u32 h = 0x811c9dc5u;
// give distinct values for different length 0 buffers.
// value taken from FNV; it has no special significance.
// expected case: string
if(!len)
{
while(*str)
{
h ^= tolower(*str++);
h *= 0x01000193u;
}
}
else
{
size_t bytes_left = len;
while(bytes_left != 0)
{
h ^= tolower(*str++);
h *= 0x01000193u;
bytes_left--;
}
}
return h;
}
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