#include "common.h" namespace { #include "farmhashsa.cc" } namespace farmhashcc { // This file provides a 32-bit hash equivalent to CityHash32 (v1.1.1) // and a 128-bit hash equivalent to CityHash128 (v1.1.1). It also provides // a seeded 32-bit hash function similar to CityHash32. #undef Fetch #define Fetch Fetch32 #undef Rotate #define Rotate Rotate32 #undef Bswap #define Bswap Bswap32 STATIC_INLINE uint32_t Hash32Len13to24(const char *s, size_t len) { uint32_t a = Fetch(s - 4 + (len >> 1)); uint32_t b = Fetch(s + 4); uint32_t c = Fetch(s + len - 8); uint32_t d = Fetch(s + (len >> 1)); uint32_t e = Fetch(s); uint32_t f = Fetch(s + len - 4); uint32_t h = len; return fmix(Mur(f, Mur(e, Mur(d, Mur(c, Mur(b, Mur(a, h))))))); } STATIC_INLINE uint32_t Hash32Len0to4(const char *s, size_t len) { uint32_t b = 0; uint32_t c = 9; for (size_t i = 0; i < len; i++) { signed char v = s[i]; b = b * c1 + v; c ^= b; } return fmix(Mur(b, Mur(len, c))); } STATIC_INLINE uint32_t Hash32Len5to12(const char *s, size_t len) { uint32_t a = len, b = len * 5, c = 9, d = b; a += Fetch(s); b += Fetch(s + len - 4); c += Fetch(s + ((len >> 1) & 4)); return fmix(Mur(c, Mur(b, Mur(a, d)))); } uint32_t Hash32(const char *s, size_t len) { if (len <= 24) { return len <= 12 ? (len <= 4 ? Hash32Len0to4(s, len) : Hash32Len5to12(s, len)) : Hash32Len13to24(s, len); } // len > 24 uint32_t h = len, g = c1 * len, f = g; uint32_t a0 = Rotate(Fetch(s + len - 4) * c1, 17) * c2; uint32_t a1 = Rotate(Fetch(s + len - 8) * c1, 17) * c2; uint32_t a2 = Rotate(Fetch(s + len - 16) * c1, 17) * c2; uint32_t a3 = Rotate(Fetch(s + len - 12) * c1, 17) * c2; uint32_t a4 = Rotate(Fetch(s + len - 20) * c1, 17) * c2; h ^= a0; h = Rotate(h, 19); h = h * 5 + 0xe6546b64; h ^= a2; h = Rotate(h, 19); h = h * 5 + 0xe6546b64; g ^= a1; g = Rotate(g, 19); g = g * 5 + 0xe6546b64; g ^= a3; g = Rotate(g, 19); g = g * 5 + 0xe6546b64; f += a4; f = Rotate(f, 19); f = f * 5 + 0xe6546b64; size_t iters = (len - 1) / 20; do { uint32_t a0 = Rotate(Fetch(s) * c1, 17) * c2; uint32_t a1 = Fetch(s + 4); uint32_t a2 = Rotate(Fetch(s + 8) * c1, 17) * c2; uint32_t a3 = Rotate(Fetch(s + 12) * c1, 17) * c2; uint32_t a4 = Fetch(s + 16); h ^= a0; h = Rotate(h, 18); h = h * 5 + 0xe6546b64; f += a1; f = Rotate(f, 19); f = f * c1; g += a2; g = Rotate(g, 18); g = g * 5 + 0xe6546b64; h ^= a3 + a1; h = Rotate(h, 19); h = h * 5 + 0xe6546b64; g ^= a4; g = Bswap(g) * 5; h += a4 * 5; h = Bswap(h); f += a0; PERMUTE3(f, h, g); s += 20; } while (--iters != 0); g = Rotate(g, 11) * c1; g = Rotate(g, 17) * c1; f = Rotate(f, 11) * c1; f = Rotate(f, 17) * c1; h = Rotate(h + g, 19); h = h * 5 + 0xe6546b64; h = Rotate(h, 17) * c1; h = Rotate(h + f, 19); h = h * 5 + 0xe6546b64; h = Rotate(h, 17) * c1; return h; } uint32_t Hash32WithSeed(const char *s, size_t len, uint32_t seed) { if (len <= 24) { if (len >= 13) return farmhashmk::Hash32Len13to24(s, len, seed * c1); else if (len >= 5) return farmhashmk::Hash32Len5to12(s, len, seed); else return farmhashmk::Hash32Len0to4(s, len, seed); } uint32_t h = farmhashmk::Hash32Len13to24(s, 24, seed ^ len); return Mur(Hash32(s + 24, len - 24) + seed, h); } #undef Fetch #define Fetch Fetch64 #undef Rotate #define Rotate Rotate64 #undef Bswap #define Bswap Bswap64 STATIC_INLINE uint64_t ShiftMix(uint64_t val) { return val ^ (val >> 47); } STATIC_INLINE uint64_t HashLen16(uint64_t u, uint64_t v) { return Hash128to64(Uint128(u, v)); } STATIC_INLINE uint64_t HashLen16(uint64_t u, uint64_t v, uint64_t mul) { // Murmur-inspired hashing. uint64_t a = (u ^ v) * mul; a ^= (a >> 47); uint64_t b = (v ^ a) * mul; b ^= (b >> 47); b *= mul; return b; } STATIC_INLINE uint64_t HashLen0to16(const char *s, size_t len) { if (len >= 8) { uint64_t mul = k2 + len * 2; uint64_t a = Fetch(s) + k2; uint64_t b = Fetch(s + len - 8); uint64_t c = Rotate(b, 37) * mul + a; uint64_t d = (Rotate(a, 25) + b) * mul; return HashLen16(c, d, mul); } if (len >= 4) { uint64_t mul = k2 + len * 2; uint64_t a = Fetch32(s); return HashLen16(len + (a << 3), Fetch32(s + len - 4), mul); } if (len > 0) { uint8_t a = s[0]; uint8_t b = s[len >> 1]; uint8_t c = s[len - 1]; uint32_t y = static_cast<uint32_t>(a) + (static_cast<uint32_t>(b) << 8); uint32_t z = len + (static_cast<uint32_t>(c) << 2); return ShiftMix(y * k2 ^ z * k0) * k2; } return k2; } // Return a 16-byte hash for 48 bytes. Quick and dirty. // Callers do best to use "random-looking" values for a and b. STATIC_INLINE pair<uint64_t, uint64_t> WeakHashLen32WithSeeds( uint64_t w, uint64_t x, uint64_t y, uint64_t z, uint64_t a, uint64_t b) { a += w; b = Rotate(b + a + z, 21); uint64_t 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_INLINE pair<uint64_t, uint64_t> WeakHashLen32WithSeeds( const char* s, uint64_t a, uint64_t b) { return WeakHashLen32WithSeeds(Fetch(s), Fetch(s + 8), Fetch(s + 16), Fetch(s + 24), a, b); } // 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_INLINE uint128_t CityMurmur(const char *s, size_t len, uint128_t seed) { uint64_t a = Uint128Low64(seed); uint64_t b = Uint128High64(seed); uint64_t c = 0; uint64_t 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 ? Fetch(s) : c)); } else { // len > 16 c = HashLen16(Fetch(s + len - 8) + k1, a); d = HashLen16(b + len, c + Fetch(s + len - 16)); a += d; do { a ^= ShiftMix(Fetch(s) * k1) * k1; a *= k1; b ^= a; c ^= ShiftMix(Fetch(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_t CityHash128WithSeed(const char *s, size_t len, uint128_t 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_t, uint64_t> v, w; uint64_t x = Uint128Low64(seed); uint64_t y = Uint128High64(seed); uint64_t z = len * k1; v.first = Rotate(y ^ k1, 49) * k1 + Fetch(s); v.second = Rotate(v.first, 42) * k1 + Fetch(s + 8); w.first = Rotate(y + z, 35) * k1 + x; w.second = Rotate(x + Fetch(s + 88), 53) * k1; // This is the same inner loop as CityHash64(), manually unrolled. do { x = Rotate(x + y + v.first + Fetch(s + 8), 37) * k1; y = Rotate(y + v.second + Fetch(s + 48), 42) * k1; x ^= w.second; y += v.first + Fetch(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 + Fetch(s + 16)); std::swap(z, x); s += 64; x = Rotate(x + y + v.first + Fetch(s + 8), 37) * k1; y = Rotate(y + v.second + Fetch(s + 48), 42) * k1; x ^= w.second; y += v.first + Fetch(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 + Fetch(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 += Fetch(s + len - tail_done + 16); x = x * k0 + w.first; z += w.second + Fetch(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)); } STATIC_INLINE uint128_t CityHash128(const char *s, size_t len) { return len >= 16 ? CityHash128WithSeed(s + 16, len - 16, Uint128(Fetch(s), Fetch(s + 8) + k0)) : CityHash128WithSeed(s, len, Uint128(k0, k1)); } uint128_t Fingerprint128(const char* s, size_t len) { return CityHash128(s, len); } } // namespace farmhashcc