merge with upstream

3 files changed, 600 insertions, 0 deletions

diff --git a/utils/city.cc b/utils/city.cc
new file mode 100644
index 00000000..f1301ce4
--- /dev/null
+++ b/utils/city.cc
@@ -0,0 +1,467 @@
+// 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 "config.h"
+#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;
+}
+
+#if !defined(WORDS_BIGENDIAN)
+
+#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  // WORDS_BIGENDIAN
+
+#if !defined(LIKELY)
+#if HAVE_BUILTIN_EXPECT
+#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));
+  }
+}
+
+#ifdef __SSE4_2__
+#include <citycrc.h>
+#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
diff --git a/utils/city.h b/utils/city.h
new file mode 100644
index 00000000..c2ab352c
--- /dev/null
+++ b/utils/city.h
@@ -0,0 +1,90 @@
+// 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 a few functions for hashing strings. On x86-64
+// hardware in 2011, CityHash64() is faster than other high-quality
+// hash functions, such as Murmur.  This is largely due to higher
+// instruction-level parallelism.  CityHash64() and CityHash128() also perform
+// well on hash-quality tests.
+//
+// CityHash128() is optimized for relatively long strings and returns
+// a 128-bit hash.  For strings more than about 2000 bytes it can be
+// faster than CityHash64().
+//
+// Functions in the CityHash family are not suitable for cryptography.
+//
+// WARNING: This code has not been tested on big-endian platforms!
+// It is known to work well on little-endian platforms that have a small penalty
+// for unaligned reads, such as current Intel and AMD moderate-to-high-end CPUs.
+//
+// By the way, for some hash functions, given strings a and b, the hash
+// of a+b is easily derived from the hashes of a and b.  This property
+// doesn't hold for any hash functions in this file.
+
+#ifndef CITY_HASH_H_
+#define CITY_HASH_H_
+
+#include <stdlib.h>  // for size_t.
+#include <stdint.h>
+#include <utility>
+
+typedef uint8_t uint8;
+typedef uint32_t uint32;
+typedef uint64_t uint64;
+typedef std::pair<uint64, uint64> uint128;
+
+inline uint64 Uint128Low64(const uint128& x) { return x.first; }
+inline uint64 Uint128High64(const uint128& x) { return x.second; }
+
+// Hash function for a byte array.
+uint64 CityHash64(const char *buf, size_t len);
+
+// Hash function for a byte array.  For convenience, a 64-bit seed is also
+// hashed into the result.
+uint64 CityHash64WithSeed(const char *buf, size_t len, uint64 seed);
+
+// Hash function for a byte array.  For convenience, two seeds are also
+// hashed into the result.
+uint64 CityHash64WithSeeds(const char *buf, size_t len,
+                           uint64 seed0, uint64 seed1);
+
+// Hash function for a byte array.
+uint128 CityHash128(const char *s, size_t len);
+
+// Hash function for a byte array.  For convenience, a 128-bit seed is also
+// hashed into the result.
+uint128 CityHash128WithSeed(const char *s, size_t len, uint128 seed);
+
+// Hash 128 input bits down to 64 bits of output.
+// This is intended to be a reasonably good hash function.
+inline uint64 Hash128to64(const uint128& x) {
+  // Murmur-inspired hashing.
+  const uint64 kMul = 0x9ddfea08eb382d69ULL;
+  uint64 a = (Uint128Low64(x) ^ Uint128High64(x)) * kMul;
+  a ^= (a >> 47);
+  uint64 b = (Uint128High64(x) ^ a) * kMul;
+  b ^= (b >> 47);
+  b *= kMul;
+  return b;
+}
+
+#endif  // CITY_HASH_H_
diff --git a/utils/citycrc.h b/utils/citycrc.h
new file mode 100644
index 00000000..318e3917
--- /dev/null
+++ b/utils/citycrc.h
@@ -0,0 +1,43 @@
+// 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 declares the subset of the CityHash functions that require
+// _mm_crc32_u64().  See the CityHash README for details.
+//
+// Functions in the CityHash family are not suitable for cryptography.
+
+#ifndef CITY_HASH_CRC_H_
+#define CITY_HASH_CRC_H_
+
+#include <city.h>
+
+// Hash function for a byte array.
+uint128 CityHashCrc128(const char *s, size_t len);
+
+// Hash function for a byte array.  For convenience, a 128-bit seed is also
+// hashed into the result.
+uint128 CityHashCrc128WithSeed(const char *s, size_t len, uint128 seed);
+
+// Hash function for a byte array.  Sets result[0] ... result[3].
+void CityHashCrc256(const char *s, size_t len, uint64 *result);
+
+#endif  // CITY_HASH_CRC_H_