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lib: add cityhash function
CityHash64 appears to be the fastest available block hashing algorithm that is good enough for dedupe. It takes much less CPU than the CRC64 function, and avoids hash-collision problems with file formats that use CRC64 as an integrity check on 4K block boundaries. Extracted from git://github.com/google/cityhash with the "CRC" hash functions (which require Intel/AMD CPU support) removed. We don't need those, and they introduce a new (if only theoretical) build-time dependency. Signed-off-by: Zygo Blaxell <bees@furryterror.org>
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Zygo Blaxell
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113
include/crucible/city.h
Normal file
113
include/crucible/city.h
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@ -0,0 +1,113 @@
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// Copyright (c) 2011 Google, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// 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, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//
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// CityHash, by Geoff Pike and Jyrki Alakuijala
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//
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// http://code.google.com/p/cityhash/
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//
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// This file provides a few functions for hashing strings. All of them are
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// high-quality functions in the sense that they pass standard tests such
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// as Austin Appleby's SMHasher. They are also fast.
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//
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// For 64-bit x86 code, on short strings, we don't know of anything faster than
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// CityHash64 that is of comparable quality. We believe our nearest competitor
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// is Murmur3. For 64-bit x86 code, CityHash64 is an excellent choice for hash
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// tables and most other hashing (excluding cryptography).
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//
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// For 64-bit x86 code, on long strings, the picture is more complicated.
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// On many recent Intel CPUs, such as Nehalem, Westmere, Sandy Bridge, etc.,
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// CityHashCrc128 appears to be faster than all competitors of comparable
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// quality. CityHash128 is also good but not quite as fast. We believe our
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// nearest competitor is Bob Jenkins' Spooky. We don't have great data for
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// other 64-bit CPUs, but for long strings we know that Spooky is slightly
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// faster than CityHash on some relatively recent AMD x86-64 CPUs, for example.
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// Note that CityHashCrc128 is declared in citycrc.h [which has been removed
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// for bees].
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//
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// For 32-bit x86 code, we don't know of anything faster than CityHash32 that
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// is of comparable quality. We believe our nearest competitor is Murmur3A.
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// (On 64-bit CPUs, it is typically faster to use the other CityHash variants.)
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//
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// Functions in the CityHash family are not suitable for cryptography.
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//
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// Please see CityHash's README file for more details on our performance
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// measurements and so on.
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//
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// WARNING: This code has been only lightly tested on big-endian platforms!
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// It is known to work well on little-endian platforms that have a small penalty
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// for unaligned reads, such as current Intel and AMD moderate-to-high-end CPUs.
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// It should work on all 32-bit and 64-bit platforms that allow unaligned reads;
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// bug reports are welcome.
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//
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// By the way, for some hash functions, given strings a and b, the hash
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// of a+b is easily derived from the hashes of a and b. This property
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// doesn't hold for any hash functions in this file.
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#ifndef CITY_HASH_H_
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#define CITY_HASH_H_
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#include <stdlib.h> // for size_t.
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#include <stdint.h>
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#include <utility>
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typedef uint8_t uint8;
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typedef uint32_t uint32;
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typedef uint64_t uint64;
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typedef std::pair<uint64, uint64> uint128;
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inline uint64 Uint128Low64(const uint128& x) { return x.first; }
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inline uint64 Uint128High64(const uint128& x) { return x.second; }
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// Hash function for a byte array.
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uint64 CityHash64(const char *buf, size_t len);
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// Hash function for a byte array. For convenience, a 64-bit seed is also
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// hashed into the result.
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uint64 CityHash64WithSeed(const char *buf, size_t len, uint64 seed);
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// Hash function for a byte array. For convenience, two seeds are also
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// hashed into the result.
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uint64 CityHash64WithSeeds(const char *buf, size_t len,
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uint64 seed0, uint64 seed1);
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// Hash function for a byte array.
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uint128 CityHash128(const char *s, size_t len);
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// Hash function for a byte array. For convenience, a 128-bit seed is also
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// hashed into the result.
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uint128 CityHash128WithSeed(const char *s, size_t len, uint128 seed);
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// Hash function for a byte array. Most useful in 32-bit binaries.
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uint32 CityHash32(const char *buf, size_t len);
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// Hash 128 input bits down to 64 bits of output.
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// This is intended to be a reasonably good hash function.
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inline uint64 Hash128to64(const uint128& x) {
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// Murmur-inspired hashing.
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const uint64 kMul = 0x9ddfea08eb382d69ULL;
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uint64 a = (Uint128Low64(x) ^ Uint128High64(x)) * kMul;
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a ^= (a >> 47);
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uint64 b = (Uint128High64(x) ^ a) * kMul;
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b ^= (b >> 47);
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b *= kMul;
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return b;
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}
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#endif // CITY_HASH_H_
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@ -5,6 +5,7 @@ default: libcrucible.a
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CRUCIBLE_OBJS = \
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chatter.o \
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city.o \
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cleanup.o \
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crc64.o \
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error.o \
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513
lib/city.cc
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513
lib/city.cc
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@ -0,0 +1,513 @@
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// Copyright (c) 2011 Google, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// 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, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//
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// CityHash, by Geoff Pike and Jyrki Alakuijala
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//
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// This file provides CityHash64() and related functions.
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//
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// It's probably possible to create even faster hash functions by
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// writing a program that systematically explores some of the space of
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// possible hash functions, by using SIMD instructions, or by
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// compromising on hash quality.
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#include "crucible/city.h"
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#include <algorithm>
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#include <string.h> // for memcpy and memset
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using namespace std;
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static uint64 UNALIGNED_LOAD64(const char *p) {
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uint64 result;
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memcpy(&result, p, sizeof(result));
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return result;
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}
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static uint32 UNALIGNED_LOAD32(const char *p) {
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uint32 result;
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memcpy(&result, p, sizeof(result));
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return result;
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}
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#ifdef _MSC_VER
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#include <stdlib.h>
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#define bswap_32(x) _byteswap_ulong(x)
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#define bswap_64(x) _byteswap_uint64(x)
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#elif defined(__APPLE__)
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// Mac OS X / Darwin features
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#include <libkern/OSByteOrder.h>
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#define bswap_32(x) OSSwapInt32(x)
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#define bswap_64(x) OSSwapInt64(x)
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#elif defined(__sun) || defined(sun)
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#include <sys/byteorder.h>
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#define bswap_32(x) BSWAP_32(x)
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#define bswap_64(x) BSWAP_64(x)
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#elif defined(__FreeBSD__)
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#include <sys/endian.h>
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#define bswap_32(x) bswap32(x)
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#define bswap_64(x) bswap64(x)
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#elif defined(__OpenBSD__)
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#include <sys/types.h>
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#define bswap_32(x) swap32(x)
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#define bswap_64(x) swap64(x)
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#elif defined(__NetBSD__)
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#include <sys/types.h>
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#include <machine/bswap.h>
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#if defined(__BSWAP_RENAME) && !defined(__bswap_32)
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#define bswap_32(x) bswap32(x)
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#define bswap_64(x) bswap64(x)
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#endif
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#else
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#include <byteswap.h>
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#endif
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#ifdef WORDS_BIGENDIAN
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#define uint32_in_expected_order(x) (bswap_32(x))
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#define uint64_in_expected_order(x) (bswap_64(x))
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#else
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#define uint32_in_expected_order(x) (x)
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#define uint64_in_expected_order(x) (x)
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#endif
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#if !defined(LIKELY)
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#if HAVE_BUILTIN_EXPECT
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#define LIKELY(x) (__builtin_expect(!!(x), 1))
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#else
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#define LIKELY(x) (x)
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#endif
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#endif
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static uint64 Fetch64(const char *p) {
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return uint64_in_expected_order(UNALIGNED_LOAD64(p));
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}
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static uint32 Fetch32(const char *p) {
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return uint32_in_expected_order(UNALIGNED_LOAD32(p));
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}
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// Some primes between 2^63 and 2^64 for various uses.
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static const uint64 k0 = 0xc3a5c85c97cb3127ULL;
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static const uint64 k1 = 0xb492b66fbe98f273ULL;
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static const uint64 k2 = 0x9ae16a3b2f90404fULL;
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// Magic numbers for 32-bit hashing. Copied from Murmur3.
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static const uint32 c1 = 0xcc9e2d51;
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static const uint32 c2 = 0x1b873593;
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// A 32-bit to 32-bit integer hash copied from Murmur3.
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static uint32 fmix(uint32 h)
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{
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h ^= h >> 16;
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h *= 0x85ebca6b;
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h ^= h >> 13;
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h *= 0xc2b2ae35;
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h ^= h >> 16;
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return h;
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}
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static uint32 Rotate32(uint32 val, int shift) {
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// Avoid shifting by 32: doing so yields an undefined result.
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return shift == 0 ? val : ((val >> shift) | (val << (32 - shift)));
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}
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#undef PERMUTE3
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#define PERMUTE3(a, b, c) do { std::swap(a, b); std::swap(a, c); } while (0)
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static uint32 Mur(uint32 a, uint32 h) {
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// Helper from Murmur3 for combining two 32-bit values.
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a *= c1;
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a = Rotate32(a, 17);
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a *= c2;
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h ^= a;
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h = Rotate32(h, 19);
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return h * 5 + 0xe6546b64;
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}
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static uint32 Hash32Len13to24(const char *s, size_t len) {
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uint32 a = Fetch32(s - 4 + (len >> 1));
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uint32 b = Fetch32(s + 4);
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uint32 c = Fetch32(s + len - 8);
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uint32 d = Fetch32(s + (len >> 1));
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uint32 e = Fetch32(s);
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uint32 f = Fetch32(s + len - 4);
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uint32 h = len;
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return fmix(Mur(f, Mur(e, Mur(d, Mur(c, Mur(b, Mur(a, h)))))));
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}
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static uint32 Hash32Len0to4(const char *s, size_t len) {
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uint32 b = 0;
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uint32 c = 9;
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for (size_t i = 0; i < len; i++) {
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signed char v = s[i];
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b = b * c1 + v;
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c ^= b;
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}
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return fmix(Mur(b, Mur(len, c)));
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}
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static uint32 Hash32Len5to12(const char *s, size_t len) {
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uint32 a = len, b = len * 5, c = 9, d = b;
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a += Fetch32(s);
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b += Fetch32(s + len - 4);
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c += Fetch32(s + ((len >> 1) & 4));
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return fmix(Mur(c, Mur(b, Mur(a, d))));
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}
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uint32 CityHash32(const char *s, size_t len) {
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if (len <= 24) {
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return len <= 12 ?
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(len <= 4 ? Hash32Len0to4(s, len) : Hash32Len5to12(s, len)) :
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Hash32Len13to24(s, len);
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}
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// len > 24
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uint32 h = len, g = c1 * len, f = g;
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uint32 a0 = Rotate32(Fetch32(s + len - 4) * c1, 17) * c2;
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uint32 a1 = Rotate32(Fetch32(s + len - 8) * c1, 17) * c2;
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uint32 a2 = Rotate32(Fetch32(s + len - 16) * c1, 17) * c2;
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uint32 a3 = Rotate32(Fetch32(s + len - 12) * c1, 17) * c2;
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uint32 a4 = Rotate32(Fetch32(s + len - 20) * c1, 17) * c2;
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h ^= a0;
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h = Rotate32(h, 19);
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h = h * 5 + 0xe6546b64;
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h ^= a2;
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h = Rotate32(h, 19);
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h = h * 5 + 0xe6546b64;
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g ^= a1;
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g = Rotate32(g, 19);
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g = g * 5 + 0xe6546b64;
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g ^= a3;
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g = Rotate32(g, 19);
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g = g * 5 + 0xe6546b64;
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f += a4;
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f = Rotate32(f, 19);
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f = f * 5 + 0xe6546b64;
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size_t iters = (len - 1) / 20;
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do {
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uint32 a0 = Rotate32(Fetch32(s) * c1, 17) * c2;
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uint32 a1 = Fetch32(s + 4);
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uint32 a2 = Rotate32(Fetch32(s + 8) * c1, 17) * c2;
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uint32 a3 = Rotate32(Fetch32(s + 12) * c1, 17) * c2;
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uint32 a4 = Fetch32(s + 16);
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h ^= a0;
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h = Rotate32(h, 18);
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h = h * 5 + 0xe6546b64;
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f += a1;
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f = Rotate32(f, 19);
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f = f * c1;
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g += a2;
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g = Rotate32(g, 18);
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g = g * 5 + 0xe6546b64;
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h ^= a3 + a1;
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h = Rotate32(h, 19);
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h = h * 5 + 0xe6546b64;
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g ^= a4;
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g = bswap_32(g) * 5;
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h += a4 * 5;
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h = bswap_32(h);
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f += a0;
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PERMUTE3(f, h, g);
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s += 20;
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} while (--iters != 0);
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g = Rotate32(g, 11) * c1;
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g = Rotate32(g, 17) * c1;
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f = Rotate32(f, 11) * c1;
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f = Rotate32(f, 17) * c1;
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h = Rotate32(h + g, 19);
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h = h * 5 + 0xe6546b64;
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h = Rotate32(h, 17) * c1;
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h = Rotate32(h + f, 19);
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h = h * 5 + 0xe6546b64;
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h = Rotate32(h, 17) * c1;
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return h;
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}
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// Bitwise right rotate. Normally this will compile to a single
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// instruction, especially if the shift is a manifest constant.
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static uint64 Rotate(uint64 val, int shift) {
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// Avoid shifting by 64: doing so yields an undefined result.
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return shift == 0 ? val : ((val >> shift) | (val << (64 - shift)));
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}
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static uint64 ShiftMix(uint64 val) {
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return val ^ (val >> 47);
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}
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static uint64 HashLen16(uint64 u, uint64 v) {
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return Hash128to64(uint128(u, v));
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}
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static uint64 HashLen16(uint64 u, uint64 v, uint64 mul) {
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// Murmur-inspired hashing.
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uint64 a = (u ^ v) * mul;
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a ^= (a >> 47);
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uint64 b = (v ^ a) * mul;
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b ^= (b >> 47);
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b *= mul;
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return b;
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}
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static uint64 HashLen0to16(const char *s, size_t len) {
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if (len >= 8) {
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uint64 mul = k2 + len * 2;
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uint64 a = Fetch64(s) + k2;
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uint64 b = Fetch64(s + len - 8);
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uint64 c = Rotate(b, 37) * mul + a;
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uint64 d = (Rotate(a, 25) + b) * mul;
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return HashLen16(c, d, mul);
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}
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if (len >= 4) {
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uint64 mul = k2 + len * 2;
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uint64 a = Fetch32(s);
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return HashLen16(len + (a << 3), Fetch32(s + len - 4), mul);
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}
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if (len > 0) {
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uint8 a = s[0];
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uint8 b = s[len >> 1];
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uint8 c = s[len - 1];
|
||||
uint32 y = static_cast<uint32>(a) + (static_cast<uint32>(b) << 8);
|
||||
uint32 z = len + (static_cast<uint32>(c) << 2);
|
||||
return ShiftMix(y * k2 ^ z * k0) * k2;
|
||||
}
|
||||
return k2;
|
||||
}
|
||||
|
||||
// This probably works well for 16-byte strings as well, but it may be overkill
|
||||
// in that case.
|
||||
static uint64 HashLen17to32(const char *s, size_t len) {
|
||||
uint64 mul = k2 + len * 2;
|
||||
uint64 a = Fetch64(s) * k1;
|
||||
uint64 b = Fetch64(s + 8);
|
||||
uint64 c = Fetch64(s + len - 8) * mul;
|
||||
uint64 d = Fetch64(s + len - 16) * k2;
|
||||
return HashLen16(Rotate(a + b, 43) + Rotate(c, 30) + d,
|
||||
a + Rotate(b + k2, 18) + c, mul);
|
||||
}
|
||||
|
||||
// Return a 16-byte hash for 48 bytes. Quick and dirty.
|
||||
// Callers do best to use "random-looking" values for a and b.
|
||||
static pair<uint64, uint64> WeakHashLen32WithSeeds(
|
||||
uint64 w, uint64 x, uint64 y, uint64 z, uint64 a, uint64 b) {
|
||||
a += w;
|
||||
b = Rotate(b + a + z, 21);
|
||||
uint64 c = a;
|
||||
a += x;
|
||||
a += y;
|
||||
b += Rotate(a, 44);
|
||||
return make_pair(a + z, b + c);
|
||||
}
|
||||
|
||||
// Return a 16-byte hash for s[0] ... s[31], a, and b. Quick and dirty.
|
||||
static pair<uint64, uint64> WeakHashLen32WithSeeds(
|
||||
const char* s, uint64 a, uint64 b) {
|
||||
return WeakHashLen32WithSeeds(Fetch64(s),
|
||||
Fetch64(s + 8),
|
||||
Fetch64(s + 16),
|
||||
Fetch64(s + 24),
|
||||
a,
|
||||
b);
|
||||
}
|
||||
|
||||
// Return an 8-byte hash for 33 to 64 bytes.
|
||||
static uint64 HashLen33to64(const char *s, size_t len) {
|
||||
uint64 mul = k2 + len * 2;
|
||||
uint64 a = Fetch64(s) * k2;
|
||||
uint64 b = Fetch64(s + 8);
|
||||
uint64 c = Fetch64(s + len - 24);
|
||||
uint64 d = Fetch64(s + len - 32);
|
||||
uint64 e = Fetch64(s + 16) * k2;
|
||||
uint64 f = Fetch64(s + 24) * 9;
|
||||
uint64 g = Fetch64(s + len - 8);
|
||||
uint64 h = Fetch64(s + len - 16) * mul;
|
||||
uint64 u = Rotate(a + g, 43) + (Rotate(b, 30) + c) * 9;
|
||||
uint64 v = ((a + g) ^ d) + f + 1;
|
||||
uint64 w = bswap_64((u + v) * mul) + h;
|
||||
uint64 x = Rotate(e + f, 42) + c;
|
||||
uint64 y = (bswap_64((v + w) * mul) + g) * mul;
|
||||
uint64 z = e + f + c;
|
||||
a = bswap_64((x + z) * mul + y) + b;
|
||||
b = ShiftMix((z + a) * mul + d + h) * mul;
|
||||
return b + x;
|
||||
}
|
||||
|
||||
uint64 CityHash64(const char *s, size_t len) {
|
||||
if (len <= 32) {
|
||||
if (len <= 16) {
|
||||
return HashLen0to16(s, len);
|
||||
} else {
|
||||
return HashLen17to32(s, len);
|
||||
}
|
||||
} else if (len <= 64) {
|
||||
return HashLen33to64(s, len);
|
||||
}
|
||||
|
||||
// For strings over 64 bytes we hash the end first, and then as we
|
||||
// loop we keep 56 bytes of state: v, w, x, y, and z.
|
||||
uint64 x = Fetch64(s + len - 40);
|
||||
uint64 y = Fetch64(s + len - 16) + Fetch64(s + len - 56);
|
||||
uint64 z = HashLen16(Fetch64(s + len - 48) + len, Fetch64(s + len - 24));
|
||||
pair<uint64, uint64> v = WeakHashLen32WithSeeds(s + len - 64, len, z);
|
||||
pair<uint64, uint64> w = WeakHashLen32WithSeeds(s + len - 32, y + k1, x);
|
||||
x = x * k1 + Fetch64(s);
|
||||
|
||||
// Decrease len to the nearest multiple of 64, and operate on 64-byte chunks.
|
||||
len = (len - 1) & ~static_cast<size_t>(63);
|
||||
do {
|
||||
x = Rotate(x + y + v.first + Fetch64(s + 8), 37) * k1;
|
||||
y = Rotate(y + v.second + Fetch64(s + 48), 42) * k1;
|
||||
x ^= w.second;
|
||||
y += v.first + Fetch64(s + 40);
|
||||
z = Rotate(z + w.first, 33) * k1;
|
||||
v = WeakHashLen32WithSeeds(s, v.second * k1, x + w.first);
|
||||
w = WeakHashLen32WithSeeds(s + 32, z + w.second, y + Fetch64(s + 16));
|
||||
std::swap(z, x);
|
||||
s += 64;
|
||||
len -= 64;
|
||||
} while (len != 0);
|
||||
return HashLen16(HashLen16(v.first, w.first) + ShiftMix(y) * k1 + z,
|
||||
HashLen16(v.second, w.second) + x);
|
||||
}
|
||||
|
||||
uint64 CityHash64WithSeed(const char *s, size_t len, uint64 seed) {
|
||||
return CityHash64WithSeeds(s, len, k2, seed);
|
||||
}
|
||||
|
||||
uint64 CityHash64WithSeeds(const char *s, size_t len,
|
||||
uint64 seed0, uint64 seed1) {
|
||||
return HashLen16(CityHash64(s, len) - seed0, seed1);
|
||||
}
|
||||
|
||||
// A subroutine for CityHash128(). Returns a decent 128-bit hash for strings
|
||||
// of any length representable in signed long. Based on City and Murmur.
|
||||
static uint128 CityMurmur(const char *s, size_t len, uint128 seed) {
|
||||
uint64 a = Uint128Low64(seed);
|
||||
uint64 b = Uint128High64(seed);
|
||||
uint64 c = 0;
|
||||
uint64 d = 0;
|
||||
signed long l = len - 16;
|
||||
if (l <= 0) { // len <= 16
|
||||
a = ShiftMix(a * k1) * k1;
|
||||
c = b * k1 + HashLen0to16(s, len);
|
||||
d = ShiftMix(a + (len >= 8 ? Fetch64(s) : c));
|
||||
} else { // len > 16
|
||||
c = HashLen16(Fetch64(s + len - 8) + k1, a);
|
||||
d = HashLen16(b + len, c + Fetch64(s + len - 16));
|
||||
a += d;
|
||||
do {
|
||||
a ^= ShiftMix(Fetch64(s) * k1) * k1;
|
||||
a *= k1;
|
||||
b ^= a;
|
||||
c ^= ShiftMix(Fetch64(s + 8) * k1) * k1;
|
||||
c *= k1;
|
||||
d ^= c;
|
||||
s += 16;
|
||||
l -= 16;
|
||||
} while (l > 0);
|
||||
}
|
||||
a = HashLen16(a, c);
|
||||
b = HashLen16(d, b);
|
||||
return uint128(a ^ b, HashLen16(b, a));
|
||||
}
|
||||
|
||||
uint128 CityHash128WithSeed(const char *s, size_t len, uint128 seed) {
|
||||
if (len < 128) {
|
||||
return CityMurmur(s, len, seed);
|
||||
}
|
||||
|
||||
// We expect len >= 128 to be the common case. Keep 56 bytes of state:
|
||||
// v, w, x, y, and z.
|
||||
pair<uint64, uint64> v, w;
|
||||
uint64 x = Uint128Low64(seed);
|
||||
uint64 y = Uint128High64(seed);
|
||||
uint64 z = len * k1;
|
||||
v.first = Rotate(y ^ k1, 49) * k1 + Fetch64(s);
|
||||
v.second = Rotate(v.first, 42) * k1 + Fetch64(s + 8);
|
||||
w.first = Rotate(y + z, 35) * k1 + x;
|
||||
w.second = Rotate(x + Fetch64(s + 88), 53) * k1;
|
||||
|
||||
// This is the same inner loop as CityHash64(), manually unrolled.
|
||||
do {
|
||||
x = Rotate(x + y + v.first + Fetch64(s + 8), 37) * k1;
|
||||
y = Rotate(y + v.second + Fetch64(s + 48), 42) * k1;
|
||||
x ^= w.second;
|
||||
y += v.first + Fetch64(s + 40);
|
||||
z = Rotate(z + w.first, 33) * k1;
|
||||
v = WeakHashLen32WithSeeds(s, v.second * k1, x + w.first);
|
||||
w = WeakHashLen32WithSeeds(s + 32, z + w.second, y + Fetch64(s + 16));
|
||||
std::swap(z, x);
|
||||
s += 64;
|
||||
x = Rotate(x + y + v.first + Fetch64(s + 8), 37) * k1;
|
||||
y = Rotate(y + v.second + Fetch64(s + 48), 42) * k1;
|
||||
x ^= w.second;
|
||||
y += v.first + Fetch64(s + 40);
|
||||
z = Rotate(z + w.first, 33) * k1;
|
||||
v = WeakHashLen32WithSeeds(s, v.second * k1, x + w.first);
|
||||
w = WeakHashLen32WithSeeds(s + 32, z + w.second, y + Fetch64(s + 16));
|
||||
std::swap(z, x);
|
||||
s += 64;
|
||||
len -= 128;
|
||||
} while (LIKELY(len >= 128));
|
||||
x += Rotate(v.first + z, 49) * k0;
|
||||
y = y * k0 + Rotate(w.second, 37);
|
||||
z = z * k0 + Rotate(w.first, 27);
|
||||
w.first *= 9;
|
||||
v.first *= k0;
|
||||
// If 0 < len < 128, hash up to 4 chunks of 32 bytes each from the end of s.
|
||||
for (size_t tail_done = 0; tail_done < len; ) {
|
||||
tail_done += 32;
|
||||
y = Rotate(x + y, 42) * k0 + v.second;
|
||||
w.first += Fetch64(s + len - tail_done + 16);
|
||||
x = x * k0 + w.first;
|
||||
z += w.second + Fetch64(s + len - tail_done);
|
||||
w.second += v.first;
|
||||
v = WeakHashLen32WithSeeds(s + len - tail_done, v.first + z, v.second);
|
||||
v.first *= k0;
|
||||
}
|
||||
// At this point our 56 bytes of state should contain more than
|
||||
// enough information for a strong 128-bit hash. We use two
|
||||
// different 56-byte-to-8-byte hashes to get a 16-byte final result.
|
||||
x = HashLen16(x, v.first);
|
||||
y = HashLen16(y + z, w.first);
|
||||
return uint128(HashLen16(x + v.second, w.second) + y,
|
||||
HashLen16(x + w.second, y + v.second));
|
||||
}
|
||||
|
||||
uint128 CityHash128(const char *s, size_t len) {
|
||||
return len >= 16 ?
|
||||
CityHash128WithSeed(s + 16, len - 16,
|
||||
uint128(Fetch64(s), Fetch64(s + 8) + k0)) :
|
||||
CityHash128WithSeed(s, len, uint128(k0, k1));
|
||||
}
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user