| // 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 |