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      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 }
    139