lib/Support/xxhash.cpp

   1 /*
   2 *  xxHash - Fast Hash algorithm
   3 *  Copyright (C) 2012-2016, Yann Collet
   4 *
   5 *  BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
   6 *
   7 *  Redistribution and use in source and binary forms, with or without
   8 *  modification, are permitted provided that the following conditions are
   9 *  met:
  10 *
  11 *  * Redistributions of source code must retain the above copyright
  12 *  notice, this list of conditions and the following disclaimer.
  13 *  * Redistributions in binary form must reproduce the above
  14 *  copyright notice, this list of conditions and the following disclaimer
  15 *  in the documentation and/or other materials provided with the
  16 *  distribution.
  17 *
  18 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19 *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20 *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21 *  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22 *  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23 *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24 *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28 *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29 *
  30 *  You can contact the author at :
  31 *  - xxHash homepage: http://www.xxhash.com
  32 *  - xxHash source repository : https://github.com/Cyan4973/xxHash
  33 */
  34
  35 /* based on revision d2df04efcbef7d7f6886d345861e5dfda4edacc1 Removed
  36  * everything but a simple interface for computing XXh64. */
  37
  38 #include "llvm/Support/xxhash.h"
  39 #include "llvm/Support/Endian.h"
  40
  41 #include <stdlib.h>
  42 #include <string.h>
  43
  44 using namespace llvm;
  45 using namespace support;
  46
  47 static uint64_t rotl64(uint64_t X, size_t R) {
  48   return (X << R) | (X >> (64 - R));
  49 }
  50
  51 static const uint64_t PRIME64_1 = 11400714785074694791ULL;
  52 static const uint64_t PRIME64_2 = 14029467366897019727ULL;
  53 static const uint64_t PRIME64_3 = 1609587929392839161ULL;
  54 static const uint64_t PRIME64_4 = 9650029242287828579ULL;
  55 static const uint64_t PRIME64_5 = 2870177450012600261ULL;
  56
  57 static uint64_t round(uint64_t Acc, uint64_t Input) {
  58   Acc += Input * PRIME64_2;
  59   Acc = rotl64(Acc, 31);
  60   Acc *= PRIME64_1;
  61   return Acc;
  62 }
  63
  64 static uint64_t mergeRound(uint64_t Acc, uint64_t Val) {
  65   Val = round(0, Val);
  66   Acc ^= Val;
  67   Acc = Acc * PRIME64_1 + PRIME64_4;
  68   return Acc;
  69 }
  70
  71 uint64_t llvm::xxHash64(StringRef Data) {
  72   size_t Len = Data.size();
  73   uint64_t Seed = 0;
  74   const unsigned char *P = Data.bytes_begin();
  75   const unsigned char *const BEnd = Data.bytes_end();
  76   uint64_t H64;
  77
  78   if (Len >= 32) {
  79     const unsigned char *const Limit = BEnd - 32;
  80     uint64_t V1 = Seed + PRIME64_1 + PRIME64_2;
  81     uint64_t V2 = Seed + PRIME64_2;
  82     uint64_t V3 = Seed + 0;
  83     uint64_t V4 = Seed - PRIME64_1;
  84
  85     do {
  86       V1 = round(V1, endian::read64le(P));
  87       P += 8;
  88       V2 = round(V2, endian::read64le(P));
  89       P += 8;
  90       V3 = round(V3, endian::read64le(P));
  91       P += 8;
  92       V4 = round(V4, endian::read64le(P));
  93       P += 8;
  94     } while (P <= Limit);
  95
  96     H64 = rotl64(V1, 1) + rotl64(V2, 7) + rotl64(V3, 12) + rotl64(V4, 18);
  97     H64 = mergeRound(H64, V1);
  98     H64 = mergeRound(H64, V2);
  99     H64 = mergeRound(H64, V3);
 100     H64 = mergeRound(H64, V4);
 101
 102   } else {
 103     H64 = Seed + PRIME64_5;
 104   }
 105
 106   H64 += (uint64_t)Len;
 107
 108   while (P + 8 <= BEnd) {
 109     uint64_t const K1 = round(0, endian::read64le(P));
 110     H64 ^= K1;
 111     H64 = rotl64(H64, 27) * PRIME64_1 + PRIME64_4;
 112     P += 8;
 113   }
 114
 115   if (P + 4 <= BEnd) {
 116     H64 ^= (uint64_t)(endian::read32le(P)) * PRIME64_1;
 117     H64 = rotl64(H64, 23) * PRIME64_2 + PRIME64_3;
 118     P += 4;
 119   }
 120
 121   while (P < BEnd) {
 122     H64 ^= (*P) * PRIME64_5;
 123     H64 = rotl64(H64, 11) * PRIME64_1;
 124     P++;
 125   }
 126
 127   H64 ^= H64 >> 33;
 128   H64 *= PRIME64_2;
 129   H64 ^= H64 >> 29;
 130   H64 *= PRIME64_3;
 131   H64 ^= H64 >> 32;
 132
 133   return H64;
 134 }
 135
 136 uint64_t llvm::xxHash64(ArrayRef<uint8_t> Data) {
 137   return xxHash64({(const char *)Data.data(), Data.size()});
 138 }