diff options
Diffstat (limited to 'absl/hash/internal/city.cc')
-rw-r--r-- | absl/hash/internal/city.cc | 246 |
1 files changed, 0 insertions, 246 deletions
diff --git a/absl/hash/internal/city.cc b/absl/hash/internal/city.cc index 8f72dd1b7d0c..122906fab042 100644 --- a/absl/hash/internal/city.cc +++ b/absl/hash/internal/city.cc @@ -340,251 +340,5 @@ uint64_t CityHash64WithSeeds(const char *s, size_t len, uint64_t seed0, 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_t a = Uint128Low64(seed); - uint64_t b = Uint128High64(seed); - uint64_t c = 0; - uint64_t d = 0; - int64_t 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. - std::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 + 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 (ABSL_PREDICT_TRUE(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)); -} } // namespace hash_internal } // namespace absl - -#ifdef __SSE4_2__ -#include <nmmintrin.h> -#include "absl/hash/internal/city_crc.h" - -namespace absl { -namespace hash_internal { - -// Requires len >= 240. -static void CityHashCrc256Long(const char *s, size_t len, uint32_t seed, - uint64_t *result) { - uint64_t a = Fetch64(s + 56) + k0; - uint64_t b = Fetch64(s + 96) + k0; - uint64_t c = result[0] = HashLen16(b, len); - uint64_t d = result[1] = Fetch64(s + 120) * k0 + len; - uint64_t e = Fetch64(s + 184) + seed; - uint64_t f = 0; - uint64_t g = 0; - uint64_t h = c + d; - uint64_t x = seed; - uint64_t y = 0; - uint64_t z = 0; - - // 240 bytes of input per iter. - size_t iters = len / 240; - len -= iters * 240; - do { -#undef CHUNK -#define CHUNK(r) \ - PERMUTE3(x, z, y); \ - b += Fetch64(s); \ - c += Fetch64(s + 8); \ - d += Fetch64(s + 16); \ - e += Fetch64(s + 24); \ - f += Fetch64(s + 32); \ - a += b; \ - h += f; \ - b += c; \ - f += d; \ - g += e; \ - e += z; \ - g += x; \ - z = _mm_crc32_u64(z, b + g); \ - y = _mm_crc32_u64(y, e + h); \ - x = _mm_crc32_u64(x, f + a); \ - e = Rotate(e, r); \ - c += e; \ - s += 40 - - CHUNK(0); - PERMUTE3(a, h, c); - CHUNK(33); - PERMUTE3(a, h, f); - CHUNK(0); - PERMUTE3(b, h, f); - CHUNK(42); - PERMUTE3(b, h, d); - CHUNK(0); - PERMUTE3(b, h, e); - CHUNK(33); - PERMUTE3(a, h, e); - } while (--iters > 0); - - while (len >= 40) { - CHUNK(29); - e ^= Rotate(a, 20); - h += Rotate(b, 30); - g ^= Rotate(c, 40); - f += Rotate(d, 34); - PERMUTE3(c, h, g); - len -= 40; - } - if (len > 0) { - s = s + len - 40; - CHUNK(33); - e ^= Rotate(a, 43); - h += Rotate(b, 42); - g ^= Rotate(c, 41); - f += Rotate(d, 40); - } - result[0] ^= h; - result[1] ^= g; - g += h; - a = HashLen16(a, g + z); - x += y << 32; - b += x; - c = HashLen16(c, z) + h; - d = HashLen16(d, e + result[0]); - g += e; - h += HashLen16(x, f); - e = HashLen16(a, d) + g; - z = HashLen16(b, c) + a; - y = HashLen16(g, h) + c; - result[0] = e + z + y + x; - a = ShiftMix((a + y) * 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_t *result) { - char buf[240]; - memcpy(buf, s, len); - memset(buf + len, 0, 240 - len); - CityHashCrc256Long(buf, 240, ~static_cast<uint32_t>(len), result); -} - -void CityHashCrc256(const char *s, size_t len, uint64_t *result) { - if (ABSL_PREDICT_TRUE(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_t result[4]; - CityHashCrc256(s, len, result); - uint64_t u = Uint128High64(seed) + result[0]; - uint64_t 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_t result[4]; - CityHashCrc256(s, len, result); - return uint128(result[2], result[3]); - } -} - -} // namespace hash_internal -} // namespace absl - -#endif |