Hash :
62662f87
        
        Author :
  
        
        Date :
2021-09-08T09:18:45
        
      
Strip "./" in includes (#925) Co-authored-by: Eugene Kliuchnikov <eustas@chromium.org>
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259
#include "sieve.h"
/* Pointer to position in (combined corpus) text. */
typedef uint32_t TextIdx;
/* Index of sample / generation. */
typedef uint16_t SampleIdx;
typedef struct Slot {
  TextIdx next;
  TextIdx offset;
  SampleIdx presence;
  SampleIdx mark;
} Slot;
static const TextIdx kNowhere = static_cast<TextIdx>(-1);
static TextIdx dryRun(TextIdx sliceLen, Slot* map, TextIdx* shortcut,
    TextIdx end, TextIdx middle, SampleIdx minPresence, SampleIdx iteration) {
  TextIdx from = kNowhere;
  TextIdx to = kNowhere;
  TextIdx result = 0;
  SampleIdx targetPresence = minPresence;
  for (TextIdx i = 0; i < end; ++i) {
    if (i == middle) {
      targetPresence++;
    }
    Slot& item = map[shortcut[i]];
    if (item.mark != iteration) {
      item.mark = iteration;
      if (item.presence >= targetPresence) {
        if ((to == kNowhere) || (to < i)) {
          if (from != kNowhere) {
            result += to - from;
          }
          from = i;
        }
        to = i + sliceLen;
      }
    }
  }
  if (from != kNowhere) {
    result += to - from;
  }
  return result;
}
static std::string createDictionary(const uint8_t* data, TextIdx sliceLen,
    Slot* map, TextIdx* shortcut, TextIdx end, TextIdx middle,
    SampleIdx minPresence, SampleIdx iteration) {
  std::string output;
  TextIdx from = kNowhere;
  TextIdx to = kNowhere;
  SampleIdx targetPresence = minPresence;
  for (TextIdx i = 0; i < end; ++i) {
    if (i == middle) {
      targetPresence++;
    }
    Slot& item = map[shortcut[i]];
    if (item.mark != iteration) {
      item.mark = iteration;
      if (item.presence >= targetPresence) {
        if ((to == kNowhere) || (to < i)) {
          if (from != kNowhere) {
            output.insert(output.end(), &data[from], &data[to]);
          }
          from = i;
        }
        to = i + sliceLen;
      }
    }
  }
  if (from != kNowhere) {
    output.insert(output.end(), &data[from], &data[to]);
  }
  return output;
}
std::string sieve_generate(size_t dictionary_size_limit, size_t slice_len,
    const std::vector<size_t>& sample_sizes, const uint8_t* sample_data) {
  /* Parameters aliasing */
  TextIdx targetSize = static_cast<TextIdx>(dictionary_size_limit);
  if (targetSize != dictionary_size_limit) {
    fprintf(stderr, "dictionary_size_limit is too large\n");
    return "";
  }
  TextIdx sliceLen = static_cast<TextIdx>(slice_len);
  if (sliceLen != slice_len) {
    fprintf(stderr, "slice_len is too large\n");
    return "";
  }
  if (sliceLen < 1) {
    fprintf(stderr, "slice_len is too small\n");
    return "";
  }
  SampleIdx numSamples = static_cast<SampleIdx>(sample_sizes.size());
  if ((numSamples != sample_sizes.size()) || (numSamples * 2 < numSamples)) {
    fprintf(stderr, "too many samples\n");
    return "";
  }
  const uint8_t* data = sample_data;
  TextIdx total = 0;
  std::vector<TextIdx> offsets;
  for (SampleIdx i = 0; i < numSamples; ++i) {
    TextIdx delta = static_cast<TextIdx>(sample_sizes[i]);
    if (delta != sample_sizes[i]) {
      fprintf(stderr, "sample is too large\n");
      return "";
    }
    if (delta == 0) {
      fprintf(stderr, "empty samples are prohibited\n");
      return "";
    }
    if (total + delta <= total) {
      fprintf(stderr, "corpus is too large\n");
      return "";
    }
    total += delta;
    offsets.push_back(total);
  }
  if (total * 2 < total) {
    fprintf(stderr, "corpus is too large\n");
    return "";
  }
  if (total < sliceLen) {
    fprintf(stderr, "slice_len is larger than corpus size\n");
    return "";
  }
  /*****************************************************************************
   * Build coverage map.
   ****************************************************************************/
  std::vector<Slot> map;
  std::vector<TextIdx> shortcut;
  map.push_back({0, 0, 0, 0});
  TextIdx end = total - sliceLen;
  TextIdx hashLen = 11;
  while (hashLen < 29 && ((1u << hashLen) < end)) {
    hashLen += 3;
  }
  hashLen -= 3;
  TextIdx hashMask = (1u << hashLen) - 1u;
  std::vector<TextIdx> hashHead(1 << hashLen);
  TextIdx hashSlot = 1;
  SampleIdx piece = 0;
  TextIdx hash = 0;
  TextIdx lShift = 3;
  TextIdx rShift = hashLen - lShift;
  for (TextIdx i = 0; i < sliceLen - 1; ++i) {
    TextIdx v = data[i];
    hash = (((hash << lShift) | (hash >> rShift)) & hashMask) ^ v;
  }
  TextIdx lShiftX = (lShift * (sliceLen - 1)) % hashLen;
  TextIdx rShiftX = hashLen - lShiftX;
  for (TextIdx i = 0; i < end; ++i) {
    TextIdx v = data[i + sliceLen - 1];
    hash = (((hash << lShift) | (hash >> rShift)) & hashMask) ^ v;
    if (offsets[piece] == i) {
      piece++;
    }
    TextIdx slot = hashHead[hash];
    while (slot != 0) {
      Slot& item = map[slot];
      TextIdx start = item.offset;
      bool miss = false;
      for (TextIdx j = 0; j < sliceLen; ++j) {
        if (data[i + j] != data[start + j]) {
          miss = true;
          break;
        }
      }
      if (!miss) {
        if (item.mark != piece) {
          item.mark = piece;
          item.presence++;
        }
        shortcut.push_back(slot);
        break;
      }
      slot = item.next;
    }
    if (slot == 0) {
      map.push_back({hashHead[hash], i, 1, piece});
      hashHead[hash] = hashSlot;
      shortcut.push_back(hashSlot);
      hashSlot++;
    }
    v = data[i];
    hash ^= ((v << lShiftX) | (v >> rShiftX)) & hashMask;
  }
  /*****************************************************************************
   * Build dictionary of specified size.
   ****************************************************************************/
  SampleIdx a = 1;
  TextIdx size = dryRun(
      sliceLen, map.data(), shortcut.data(), end, end, a, ++piece);
  /* Maximal output is smaller than target. */
  if (size <= targetSize) {
    return createDictionary(
        data, sliceLen, map.data(), shortcut.data(), end, end, a, ++piece);
  }
  SampleIdx b = numSamples;
  size = dryRun(sliceLen, map.data(), shortcut.data(), end, end, b, ++piece);
  if (size == targetSize) {
    return createDictionary(
        data, sliceLen, map.data(), shortcut.data(), end, end, b, ++piece);
  }
  /* Run binary search. */
  if (size < targetSize) {
    /* size(a) > targetSize > size(b) && a < m < b */
    while (a + 1 < b) {
      SampleIdx m = static_cast<SampleIdx>((a + b) / 2);
      size = dryRun(
          sliceLen, map.data(), shortcut.data(), end, end, m, ++piece);
      if (size < targetSize) {
        b = m;
      } else if (size > targetSize) {
        a = m;
      } else {
        return createDictionary(
            data, sliceLen, map.data(), shortcut.data(), end, end, b, ++piece);
      }
    }
  } else {
    a = b;
  }
  /* size(minPresence) > targetSize > size(minPresence + 1) */
  SampleIdx minPresence = a;
  TextIdx c = 0;
  TextIdx d = end;
  /* size(a) < targetSize < size(b) && a < m < b */
  while (c + 1 < d) {
    TextIdx m = (c + d) / 2;
    size = dryRun(
        sliceLen, map.data(), shortcut.data(), end, m, minPresence, ++piece);
    if (size < targetSize) {
      c = m;
    } else if (size > targetSize) {
      d = m;
    } else {
      return createDictionary(data, sliceLen, map.data(), shortcut.data(), end,
          m, minPresence, ++piece);
    }
  }
  bool unrestricted = false;
  if (minPresence <= 2 && !unrestricted) {
    minPresence = 2;
    c = end;
  }
  return createDictionary(data, sliceLen, map.data(), shortcut.data(), end, c,
      minPresence, ++piece);
}