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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.
+//
+// CityHash, by Geoff Pike and Jyrki Alakuijala
+//
+// This file provides CityHash64() and related functions.
+//
+// It's probably possible to create even faster hash functions by
+// writing a program that systematically explores some of the space of
+// possible hash functions, by using SIMD instructions, or by
+// compromising on hash quality.
+
+#include "City.h"
+
+#include <algorithm>
+#include <string.h> // for memcpy and memset
+
+using namespace std;
+
+static uint64 UNALIGNED_LOAD64(const char *p) {
+ uint64 result;
+ memcpy(&result, p, sizeof(result));
+ return result;
+}
+
+static uint32 UNALIGNED_LOAD32(const char *p) {
+ uint32 result;
+ memcpy(&result, p, sizeof(result));
+ return result;
+}
+
+#ifndef __BIG_ENDIAN__
+
+#define uint32_in_expected_order(x) (x)
+#define uint64_in_expected_order(x) (x)
+
+#else
+
+#ifdef _MSC_VER
+#include <stdlib.h>
+#define bswap_32(x) _byteswap_ulong(x)
+#define bswap_64(x) _byteswap_uint64(x)
+
+#elif defined(__APPLE__)
+// Mac OS X / Darwin features
+#include <libkern/OSByteOrder.h>
+#define bswap_32(x) OSSwapInt32(x)
+#define bswap_64(x) OSSwapInt64(x)
+
+#else
+#include <byteswap.h>
+#endif
+
+#define uint32_in_expected_order(x) (bswap_32(x))
+#define uint64_in_expected_order(x) (bswap_64(x))
+
+#endif // __BIG_ENDIAN__
+
+#if !defined(LIKELY)
+#if defined(__GNUC__) || defined(__INTEL_COMPILER)
+#define LIKELY(x) (__builtin_expect(!!(x), 1))
+#else
+#define LIKELY(x) (x)
+#endif
+#endif
+
+static uint64 Fetch64(const char *p) {
+ return uint64_in_expected_order(UNALIGNED_LOAD64(p));
+}
+
+static uint32 Fetch32(const char *p) {
+ return uint32_in_expected_order(UNALIGNED_LOAD32(p));
+}
+
+// Some primes between 2^63 and 2^64 for various uses.
+static const uint64 k0 = 0xc3a5c85c97cb3127ULL;
+static const uint64 k1 = 0xb492b66fbe98f273ULL;
+static const uint64 k2 = 0x9ae16a3b2f90404fULL;
+static const uint64 k3 = 0xc949d7c7509e6557ULL;
+
+// Bitwise right rotate. Normally this will compile to a single
+// instruction, especially if the shift is a manifest constant.
+static uint64 Rotate(uint64 val, int shift) {
+ // Avoid shifting by 64: doing so yields an undefined result.
+ return shift == 0 ? val : ((val >> shift) | (val << (64 - shift)));
+}
+
+// Equivalent to Rotate(), but requires the second arg to be non-zero.
+// On x86-64, and probably others, it's possible for this to compile
+// to a single instruction if both args are already in registers.
+static uint64 RotateByAtLeast1(uint64 val, int shift) {
+ return (val >> shift) | (val << (64 - shift));
+}
+
+static uint64 ShiftMix(uint64 val) {
+ return val ^ (val >> 47);
+}
+
+static uint64 HashLen16(uint64 u, uint64 v) {
+ return Hash128to64(uint128(u, v));
+}
+
+static uint64 HashLen0to16(const char *s, size_t len) {
+ if (len > 8) {
+ uint64 a = Fetch64(s);
+ uint64 b = Fetch64(s + len - 8);
+ return HashLen16(a, RotateByAtLeast1(b + len, len)) ^ b;
+ }
+ if (len >= 4) {
+ uint64 a = Fetch32(s);
+ return HashLen16(len + (a << 3), Fetch32(s + len - 4));
+ }
+ if (len > 0) {
+ uint8 a = s[0];
+ uint8 b = s[len >> 1];
+ 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 * k3) * 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 a = Fetch64(s) * k1;
+ uint64 b = Fetch64(s + 8);
+ uint64 c = Fetch64(s + len - 8) * k2;
+ uint64 d = Fetch64(s + len - 16) * k0;
+ return HashLen16(Rotate(a - b, 43) + Rotate(c, 30) + d,
+ a + Rotate(b ^ k3, 20) - c + len);
+}
+
+// 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 z = Fetch64(s + 24);
+ uint64 a = Fetch64(s) + (len + Fetch64(s + len - 16)) * k0;
+ uint64 b = Rotate(a + z, 52);
+ uint64 c = Rotate(a, 37);
+ a += Fetch64(s + 8);
+ c += Rotate(a, 7);
+ a += Fetch64(s + 16);
+ uint64 vf = a + z;
+ uint64 vs = b + Rotate(a, 31) + c;
+ a = Fetch64(s + 16) + Fetch64(s + len - 32);
+ z = Fetch64(s + len - 8);
+ b = Rotate(a + z, 52);
+ c = Rotate(a, 37);
+ a += Fetch64(s + len - 24);
+ c += Rotate(a, 7);
+ a += Fetch64(s + len - 16);
+ uint64 wf = a + z;
+ uint64 ws = b + Rotate(a, 31) + c;
+ uint64 r = ShiftMix((vf + ws) * k2 + (wf + vs) * k0);
+ return ShiftMix(r * k0 + vs) * k2;
+}
+
+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;
+ z += Rotate(w.first, 37) * 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);
+ }
+ // 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) {
+ if (len >= 16) {
+ return CityHash128WithSeed(s + 16,
+ len - 16,
+ uint128(Fetch64(s) ^ k3,
+ Fetch64(s + 8)));
+ } else if (len >= 8) {
+ return CityHash128WithSeed(NULL,
+ 0,
+ uint128(Fetch64(s) ^ (len * k0),
+ Fetch64(s + len - 8) ^ k1));
+ } else {
+ return CityHash128WithSeed(s, len, uint128(k0, k1));
+ }
+}
+
+#if defined(__SSE4_2__) && defined(__x86_64__)
+#include <nmmintrin.h>
+
+// Requires len >= 240.
+static void CityHashCrc256Long(const char *s, size_t len,
+ uint32 seed, uint64 *result) {
+ uint64 a = Fetch64(s + 56) + k0;
+ uint64 b = Fetch64(s + 96) + k0;
+ uint64 c = result[0] = HashLen16(b, len);
+ uint64 d = result[1] = Fetch64(s + 120) * k0 + len;
+ uint64 e = Fetch64(s + 184) + seed;
+ uint64 f = seed;
+ uint64 g = 0;
+ uint64 h = 0;
+ uint64 i = 0;
+ uint64 j = 0;
+ uint64 t = c + d;
+
+ // 240 bytes of input per iter.
+ size_t iters = len / 240;
+ len -= iters * 240;
+ do {
+#define CHUNK(multiplier, z) \
+ { \
+ uint64 old_a = a; \
+ a = Rotate(b, 41 ^ z) * multiplier + Fetch64(s); \
+ b = Rotate(c, 27 ^ z) * multiplier + Fetch64(s + 8); \
+ c = Rotate(d, 41 ^ z) * multiplier + Fetch64(s + 16); \
+ d = Rotate(e, 33 ^ z) * multiplier + Fetch64(s + 24); \
+ e = Rotate(t, 25 ^ z) * multiplier + Fetch64(s + 32); \
+ t = old_a; \
+ } \
+ f = _mm_crc32_u64(f, a); \
+ g = _mm_crc32_u64(g, b); \
+ h = _mm_crc32_u64(h, c); \
+ i = _mm_crc32_u64(i, d); \
+ j = _mm_crc32_u64(j, e); \
+ s += 40
+
+ CHUNK(1, 1); CHUNK(k0, 0);
+ CHUNK(1, 1); CHUNK(k0, 0);
+ CHUNK(1, 1); CHUNK(k0, 0);
+ } while (--iters > 0);
+
+ while (len >= 40) {
+ CHUNK(k0, 0);
+ len -= 40;
+ }
+ if (len > 0) {
+ s = s + len - 40;
+ CHUNK(k0, 0);
+ }
+ j += i << 32;
+ a = HashLen16(a, j);
+ h += g << 32;
+ b += h;
+ c = HashLen16(c, f) + i;
+ d = HashLen16(d, e + result[0]);
+ j += e;
+ i += HashLen16(h, t);
+ e = HashLen16(a, d) + j;
+ f = HashLen16(b, c) + a;
+ g = HashLen16(j, i) + c;
+ result[0] = e + f + g + h;
+ a = ShiftMix((a + g) * k0) * k0 + b;
+ result[1] += a + result[0];
+ a = ShiftMix(a * k0) * k0 + c;
+ result[2] = a + result[1];
+ a = ShiftMix((a + e) * k0) * k0;
+ result[3] = a + result[2];
+}
+
+// Requires len < 240.
+static void CityHashCrc256Short(const char *s, size_t len, uint64 *result) {
+ char buf[240];
+ memcpy(buf, s, len);
+ memset(buf + len, 0, 240 - len);
+ CityHashCrc256Long(buf, 240, ~static_cast<uint32>(len), result);
+}
+
+void CityHashCrc256(const char *s, size_t len, uint64 *result) {
+ if (LIKELY(len >= 240)) {
+ CityHashCrc256Long(s, len, 0, result);
+ } else {
+ CityHashCrc256Short(s, len, result);
+ }
+}
+
+uint128 CityHashCrc128WithSeed(const char *s, size_t len, uint128 seed) {
+ if (len <= 900) {
+ return CityHash128WithSeed(s, len, seed);
+ } else {
+ uint64 result[4];
+ CityHashCrc256(s, len, result);
+ uint64 u = Uint128High64(seed) + result[0];
+ uint64 v = Uint128Low64(seed) + result[1];
+ return uint128(HashLen16(u, v + result[2]),
+ HashLen16(Rotate(v, 32), u * k0 + result[3]));
+ }
+}
+
+uint128 CityHashCrc128(const char *s, size_t len) {
+ if (len <= 900) {
+ return CityHash128(s, len);
+ } else {
+ uint64 result[4];
+ CityHashCrc256(s, len, result);
+ return uint128(result[2], result[3]);
+ }
+}
+
+#endif
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-04 23:54:13 +0000