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// Copyright (c) 2011 Google, Inc.
//
// 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.
/*
* Copyright (c) 2017 by Delphix. All rights reserved.
*/
#include <sys/cityhash.h>
#define HASH_K1 0xb492b66fbe98f273ULL
#define HASH_K2 0x9ae16a3b2f90404fULL
/*
* Bitwise right rotate. Normally this will compile to a single
* instruction.
*/
static inline uint64_t
rotate(uint64_t val, int shift)
{
// Avoid shifting by 64: doing so yields an undefined result.
return (shift == 0 ? val : (val >> shift) | (val << (64 - shift)));
}
static inline uint64_t
cityhash_helper(uint64_t u, uint64_t v, uint64_t mul)
{
uint64_t a = (u ^ v) * mul;
a ^= (a >> 47);
uint64_t b = (v ^ a) * mul;
b ^= (b >> 47);
b *= mul;
return (b);
}
uint64_t
cityhash4(uint64_t w1, uint64_t w2, uint64_t w3, uint64_t w4)
{
uint64_t mul = HASH_K2 + 64;
uint64_t a = w1 * HASH_K1;
uint64_t b = w2;
uint64_t c = w4 * mul;
uint64_t d = w3 * HASH_K2;
return (cityhash_helper(rotate(a + b, 43) + rotate(c, 30) + d,
a + rotate(b + HASH_K2, 18) + c, mul));
}
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