pv/data/logicsegment.cpp

   1 /*
   2  * This file is part of the PulseView project.
   3  *
   4  * Copyright (C) 2012 Joel Holdsworth <joel@airwebreathe.org.uk>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include "config.h" // For HAVE_UNALIGNED_LITTLE_ENDIAN_ACCESS
  21
  22 #include <extdef.h>
  23
  24 #include <cassert>
  25 #include <cmath>
  26 #include <cstdlib>
  27 #include <cstring>
  28 #include <cstdint>
  29
  30 #include "logic.hpp"
  31 #include "logicsegment.hpp"
  32
  33 #include <libsigrokcxx/libsigrokcxx.hpp>
  34
  35 using std::lock_guard;
  36 using std::recursive_mutex;
  37 using std::max;
  38 using std::min;
  39 using std::shared_ptr;
  40 using std::vector;
  41
  42 using sigrok::Logic;
  43
  44 namespace pv {
  45 namespace data {
  46
  47 const int LogicSegment::MipMapScalePower = 4;
  48 const int LogicSegment::MipMapScaleFactor = 1 << MipMapScalePower;
  49 const float LogicSegment::LogMipMapScaleFactor = logf(MipMapScaleFactor);
  50 const uint64_t LogicSegment::MipMapDataUnit = 64 * 1024; // bytes
  51
  52 LogicSegment::LogicSegment(pv::data::Logic& owner, uint32_t segment_id,
  53         unsigned int unit_size, uint64_t samplerate) :
  54         Segment(segment_id, samplerate, unit_size),
  55         owner_(owner),
  56         last_append_sample_(0),
  57         last_append_accumulator_(0),
  58         last_append_extra_(0)
  59 {
  60         memset(mip_map_, 0, sizeof(mip_map_));
  61 }
  62
  63 LogicSegment::~LogicSegment()
  64 {
  65         lock_guard<recursive_mutex> lock(mutex_);
  66         for (MipMapLevel &l : mip_map_)
  67                 free(l.data);
  68 }
  69
  70 template <class T>
  71 void LogicSegment::downsampleTmain(const T*&in, T &acc, T &prev)
  72 {
  73         // Accumulate one sample at a time
  74         for (uint64_t i = 0; i < MipMapScaleFactor; i++) {
  75                 T sample = *in++;
  76                 acc |= prev ^ sample;
  77                 prev = sample;
  78         }
  79 }
  80
  81 template <>
  82 void LogicSegment::downsampleTmain<uint8_t>(const uint8_t*&in, uint8_t &acc, uint8_t &prev)
  83 {
  84         // Handle 8 bit samples in 32 bit steps
  85         uint32_t prev32 = prev | prev << 8 | prev << 16 | prev << 24;
  86         uint32_t acc32 = acc;
  87         const uint32_t *in32 = (const uint32_t*)in;
  88         for (uint64_t i = 0; i < MipMapScaleFactor; i += 4) {
  89                 uint32_t sample32 = *in32++;
  90                 acc32 |= prev32 ^ sample32;
  91                 prev32 = sample32;
  92         }
  93         // Reduce result back to uint8_t
  94 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
  95         prev = (prev32 >> 24) & 0xff; // MSB is last
  96 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
  97         prev = prev32 & 0xff; // LSB is last
  98 #else
  99 #error Endianness unknown
 100 #endif
 101         acc |= acc32 & 0xff;
 102         acc |= (acc32 >> 8) & 0xff;
 103         acc |= (acc32 >> 16) & 0xff;
 104         acc |= (acc32 >> 24) & 0xff;
 105         in = (const uint8_t*)in32;
 106 }
 107
 108 template <>
 109 void LogicSegment::downsampleTmain<uint16_t>(const uint16_t*&in, uint16_t &acc, uint16_t &prev)
 110 {
 111         // Handle 16 bit samples in 32 bit steps
 112         uint32_t prev32 = prev | prev << 16;
 113         uint32_t acc32 = acc;
 114         const uint32_t *in32 = (const uint32_t*)in;
 115         for (uint64_t i = 0; i < MipMapScaleFactor; i += 2) {
 116                 uint32_t sample32 = *in32++;
 117                 acc32 |= prev32 ^ sample32;
 118                 prev32 = sample32;
 119         }
 120         // Reduce result back to uint16_t
 121 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 122         prev = (prev32 >> 16) & 0xffff; // MSB is last
 123 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
 124         prev = prev32 & 0xffff; // LSB is last
 125 #else
 126 #error Endian unknown
 127 #endif
 128         acc |= acc32 & 0xffff;
 129         acc |= (acc32 >> 16) & 0xffff;
 130         in = (const uint16_t*)in32;
 131 }
 132
 133 template <class T>
 134 void LogicSegment::downsampleT(const uint8_t *in_, uint8_t *&out_, uint64_t len)
 135 {
 136         const T *in = (const T*)in_;
 137         T *out = (T*)out_;
 138         T prev = last_append_sample_;
 139         T acc = last_append_accumulator_;
 140
 141         // Try to complete the previous downsample
 142         if (last_append_extra_) {
 143                 while (last_append_extra_ < MipMapScaleFactor && len > 0) {
 144                         T sample = *in++;
 145                         acc |= prev ^ sample;
 146                         prev = sample;
 147                         last_append_extra_++;
 148                         len--;
 149                 }
 150                 if (!len) {
 151                         // Not enough samples available to complete downsample
 152                         last_append_sample_ = prev;
 153                         last_append_accumulator_ = acc;
 154                         return;
 155                 }
 156                 // We have a complete downsample
 157                 *out++ = acc;
 158                 acc = 0;
 159                 last_append_extra_ = 0;
 160         }
 161
 162         // Handle complete blocks of MipMapScaleFactor samples
 163         while (len >= MipMapScaleFactor) {
 164                 downsampleTmain<T>(in, acc, prev);
 165                 len -= MipMapScaleFactor;
 166                 // Output downsample
 167                 *out++ = acc;
 168                 acc = 0;
 169         }
 170
 171         // Process remainder, not enough for a complete sample
 172         while (len > 0) {
 173                 T sample = *in++;
 174                 acc |= prev ^ sample;
 175                 prev = sample;
 176                 last_append_extra_++;
 177                 len--;
 178         }
 179
 180         // Update context
 181         last_append_sample_ = prev;
 182         last_append_accumulator_ = acc;
 183         out_ = (uint8_t *)out;
 184 }
 185
 186 void LogicSegment::downsampleGeneric(const uint8_t *in, uint8_t *&out, uint64_t len)
 187 {
 188         // Downsample using the generic unpack_sample()
 189         // which can handle any width between 1 and 8 bytes
 190         uint64_t prev = last_append_sample_;
 191         uint64_t acc = last_append_accumulator_;
 192
 193         // Try to complete the previous downsample
 194         if (last_append_extra_) {
 195                 while (last_append_extra_ < MipMapScaleFactor && len > 0) {
 196                         const uint64_t sample = unpack_sample(in);
 197                         in += unit_size_;
 198                         acc |= prev ^ sample;
 199                         prev = sample;
 200                         last_append_extra_++;
 201                         len--;
 202                 }
 203                 if (!len) {
 204                         // Not enough samples available to complete downsample
 205                         last_append_sample_ = prev;
 206                         last_append_accumulator_ = acc;
 207                         return;
 208                 }
 209                 // We have a complete downsample
 210                 pack_sample(out, acc);
 211                 out += unit_size_;
 212                 acc = 0;
 213                 last_append_extra_ = 0;
 214         }
 215
 216         // Handle complete blocks of MipMapScaleFactor samples
 217         while (len >= MipMapScaleFactor) {
 218                 // Accumulate one sample at a time
 219                 for (uint64_t i = 0; i < MipMapScaleFactor; i++) {
 220                         const uint64_t sample = unpack_sample(in);
 221                         in += unit_size_;
 222                         acc |= prev ^ sample;
 223                         prev = sample;
 224                 }
 225                 len -= MipMapScaleFactor;
 226                 // Output downsample
 227                 pack_sample(out, acc);
 228                 out += unit_size_;
 229                 acc = 0;
 230         }
 231
 232         // Process remainder, not enough for a complete sample
 233         while (len > 0) {
 234                 const uint64_t sample = unpack_sample(in);
 235                 in += unit_size_;
 236                 acc |= prev ^ sample;
 237                 prev = sample;
 238                 last_append_extra_++;
 239                 len--;
 240         }
 241
 242         // Update context
 243         last_append_sample_ = prev;
 244         last_append_accumulator_ = acc;
 245 }
 246
 247 inline uint64_t LogicSegment::unpack_sample(const uint8_t *ptr) const
 248 {
 249 #ifdef HAVE_UNALIGNED_LITTLE_ENDIAN_ACCESS
 250         return *(uint64_t*)ptr;
 251 #else
 252         uint64_t value = 0;
 253         switch (unit_size_) {
 254         default:
 255                 value |= ((uint64_t)ptr[7]) << 56;
 256                 /* FALLTHRU */
 257         case 7:
 258                 value |= ((uint64_t)ptr[6]) << 48;
 259                 /* FALLTHRU */
 260         case 6:
 261                 value |= ((uint64_t)ptr[5]) << 40;
 262                 /* FALLTHRU */
 263         case 5:
 264                 value |= ((uint64_t)ptr[4]) << 32;
 265                 /* FALLTHRU */
 266         case 4:
 267                 value |= ((uint32_t)ptr[3]) << 24;
 268                 /* FALLTHRU */
 269         case 3:
 270                 value |= ((uint32_t)ptr[2]) << 16;
 271                 /* FALLTHRU */
 272         case 2:
 273                 value |= ptr[1] << 8;
 274                 /* FALLTHRU */
 275         case 1:
 276                 value |= ptr[0];
 277                 /* FALLTHRU */
 278         case 0:
 279                 break;
 280         }
 281         return value;
 282 #endif
 283 }
 284
 285 inline void LogicSegment::pack_sample(uint8_t *ptr, uint64_t value)
 286 {
 287 #ifdef HAVE_UNALIGNED_LITTLE_ENDIAN_ACCESS
 288         *(uint64_t*)ptr = value;
 289 #else
 290         switch (unit_size_) {
 291         default:
 292                 ptr[7] = value >> 56;
 293                 /* FALLTHRU */
 294         case 7:
 295                 ptr[6] = value >> 48;
 296                 /* FALLTHRU */
 297         case 6:
 298                 ptr[5] = value >> 40;
 299                 /* FALLTHRU */
 300         case 5:
 301                 ptr[4] = value >> 32;
 302                 /* FALLTHRU */
 303         case 4:
 304                 ptr[3] = value >> 24;
 305                 /* FALLTHRU */
 306         case 3:
 307                 ptr[2] = value >> 16;
 308                 /* FALLTHRU */
 309         case 2:
 310                 ptr[1] = value >> 8;
 311                 /* FALLTHRU */
 312         case 1:
 313                 ptr[0] = value;
 314                 /* FALLTHRU */
 315         case 0:
 316                 break;
 317         }
 318 #endif
 319 }
 320
 321 void LogicSegment::append_payload(shared_ptr<sigrok::Logic> logic)
 322 {
 323         assert(unit_size_ == logic->unit_size());
 324         assert((logic->data_length() % unit_size_) == 0);
 325
 326         append_payload(logic->data_pointer(), logic->data_length());
 327 }
 328
 329 void LogicSegment::append_payload(void *data, uint64_t data_size)
 330 {
 331         assert((data_size % unit_size_) == 0);
 332
 333         lock_guard<recursive_mutex> lock(mutex_);
 334
 335         const uint64_t prev_sample_count = sample_count_;
 336         const uint64_t sample_count = data_size / unit_size_;
 337
 338         append_samples(data, sample_count);
 339
 340         // Generate the first mip-map from the data
 341         append_payload_to_mipmap();
 342
 343         if (sample_count > 1)
 344                 owner_.notify_samples_added(this, prev_sample_count + 1,
 345                         prev_sample_count + 1 + sample_count);
 346         else
 347                 owner_.notify_samples_added(this, prev_sample_count + 1,
 348                         prev_sample_count + 1);
 349 }
 350
 351 void LogicSegment::get_samples(int64_t start_sample,
 352         int64_t end_sample,     uint8_t* dest) const
 353 {
 354         assert(start_sample >= 0);
 355         assert(start_sample <= (int64_t)sample_count_);
 356         assert(end_sample >= 0);
 357         assert(end_sample <= (int64_t)sample_count_);
 358         assert(start_sample <= end_sample);
 359         assert(dest != nullptr);
 360
 361         lock_guard<recursive_mutex> lock(mutex_);
 362
 363         get_raw_samples(start_sample, (end_sample - start_sample), dest);
 364 }
 365
 366 void LogicSegment::get_subsampled_edges(
 367         vector<EdgePair> &edges,
 368         uint64_t start, uint64_t end,
 369         float min_length, int sig_index, bool first_change_only)
 370 {
 371         uint64_t index = start;
 372         unsigned int level;
 373         bool last_sample;
 374         bool fast_forward;
 375
 376         assert(start <= end);
 377         assert(min_length > 0);
 378         assert(sig_index >= 0);
 379         assert(sig_index < 64);
 380
 381         lock_guard<recursive_mutex> lock(mutex_);
 382
 383         // Make sure we only process as many samples as we have
 384         if (end > get_sample_count())
 385                 end = get_sample_count();
 386
 387         const uint64_t block_length = (uint64_t)max(min_length, 1.0f);
 388         const unsigned int min_level = max((int)floorf(logf(min_length) /
 389                 LogMipMapScaleFactor) - 1, 0);
 390         const uint64_t sig_mask = 1ULL << sig_index;
 391
 392         // Store the initial state
 393         last_sample = (get_unpacked_sample(start) & sig_mask) != 0;
 394         if (!first_change_only)
 395                 edges.emplace_back(index++, last_sample);
 396
 397         while (index + block_length <= end) {
 398                 //----- Continue to search -----//
 399                 level = min_level;
 400
 401                 // We cannot fast-forward if there is no mip-map data at
 402                 // the minimum level.
 403                 fast_forward = (mip_map_[level].data != nullptr);
 404
 405                 if (min_length < MipMapScaleFactor) {
 406                         // Search individual samples up to the beginning of
 407                         // the next first level mip map block
 408                         const uint64_t final_index = min(end, pow2_ceil(index, MipMapScalePower));
 409
 410                         for (; index < final_index &&
 411                                         (index & ~((uint64_t)(~0) << MipMapScalePower)) != 0;
 412                                         index++) {
 413
 414                                 const bool sample = (get_unpacked_sample(index) & sig_mask) != 0;
 415
 416                                 // If there was a change we cannot fast forward
 417                                 if (sample != last_sample) {
 418                                         fast_forward = false;
 419                                         break;
 420                                 }
 421                         }
 422                 } else {
 423                         // If resolution is less than a mip map block,
 424                         // round up to the beginning of the mip-map block
 425                         // for this level of detail
 426                         const int min_level_scale_power = (level + 1) * MipMapScalePower;
 427                         index = pow2_ceil(index, min_level_scale_power);
 428                         if (index >= end)
 429                                 break;
 430
 431                         // We can fast forward only if there was no change
 432                         const bool sample = (get_unpacked_sample(index) & sig_mask) != 0;
 433                         if (last_sample != sample)
 434                                 fast_forward = false;
 435                 }
 436
 437                 if (fast_forward) {
 438
 439                         // Fast forward: This involves zooming out to higher
 440                         // levels of the mip map searching for changes, then
 441                         // zooming in on them to find the point where the edge
 442                         // begins.
 443
 444                         // Slide right and zoom out at the beginnings of mip-map
 445                         // blocks until we encounter a change
 446                         while (true) {
 447                                 const int level_scale_power = (level + 1) * MipMapScalePower;
 448                                 const uint64_t offset = index >> level_scale_power;
 449
 450                                 // Check if we reached the last block at this
 451                                 // level, or if there was a change in this block
 452                                 if (offset >= mip_map_[level].length ||
 453                                         (get_subsample(level, offset) & sig_mask))
 454                                         break;
 455
 456                                 if ((offset & ~((uint64_t)(~0) << MipMapScalePower)) == 0) {
 457                                         // If we are now at the beginning of a
 458                                         // higher level mip-map block ascend one
 459                                         // level
 460                                         if ((level + 1 >= ScaleStepCount) || (!mip_map_[level + 1].data))
 461                                                 break;
 462
 463                                         level++;
 464                                 } else {
 465                                         // Slide right to the beginning of the
 466                                         // next mip map block
 467                                         index = pow2_ceil(index + 1, level_scale_power);
 468                                 }
 469                         }
 470
 471                         // Zoom in, and slide right until we encounter a change,
 472                         // and repeat until we reach min_level
 473                         while (true) {
 474                                 assert(mip_map_[level].data);
 475
 476                                 const int level_scale_power = (level + 1) * MipMapScalePower;
 477                                 const uint64_t offset = index >> level_scale_power;
 478
 479                                 // Check if we reached the last block at this
 480                                 // level, or if there was a change in this block
 481                                 if (offset >= mip_map_[level].length ||
 482                                                 (get_subsample(level, offset) & sig_mask)) {
 483                                         // Zoom in unless we reached the minimum
 484                                         // zoom
 485                                         if (level == min_level)
 486                                                 break;
 487
 488                                         level--;
 489                                 } else {
 490                                         // Slide right to the beginning of the
 491                                         // next mip map block
 492                                         index = pow2_ceil(index + 1, level_scale_power);
 493                                 }
 494                         }
 495
 496                         // If individual samples within the limit of resolution,
 497                         // do a linear search for the next transition within the
 498                         // block
 499                         if (min_length < MipMapScaleFactor) {
 500                                 for (; index < end; index++) {
 501                                         const bool sample = (get_unpacked_sample(index) & sig_mask) != 0;
 502                                         if (sample != last_sample)
 503                                                 break;
 504                                 }
 505                         }
 506                 }
 507
 508                 //----- Store the edge -----//
 509
 510                 // Take the last sample of the quanization block
 511                 const int64_t final_index = index + block_length;
 512                 if (index + block_length > end)
 513                         break;
 514
 515                 // Store the final state
 516                 const bool final_sample = (get_unpacked_sample(final_index - 1) & sig_mask) != 0;
 517                 edges.emplace_back(index, final_sample);
 518
 519                 index = final_index;
 520                 last_sample = final_sample;
 521
 522                 if (first_change_only)
 523                         break;
 524         }
 525
 526         // Add the final state
 527         if (!first_change_only) {
 528                 const bool end_sample = get_unpacked_sample(end) & sig_mask;
 529                 if (last_sample != end_sample)
 530                         edges.emplace_back(end, end_sample);
 531                 edges.emplace_back(end + 1, end_sample);
 532         }
 533 }
 534
 535 void LogicSegment::get_surrounding_edges(vector<EdgePair> &dest,
 536         uint64_t origin_sample, float min_length, int sig_index)
 537 {
 538         if (origin_sample >= sample_count_)
 539                 return;
 540
 541         // Put the edges vector on the heap, it can become quite big until we can
 542         // use a get_subsampled_edges() implementation that searches backwards
 543         vector<EdgePair>* edges = new vector<EdgePair>;
 544
 545         // Get all edges to the left of origin_sample
 546         get_subsampled_edges(*edges, 0, origin_sample, min_length, sig_index, false);
 547
 548         // If we don't specify "first only", the first and last edge are the states
 549         // at samples 0 and origin_sample. If only those exist, there are no edges
 550         if (edges->size() == 2) {
 551                 delete edges;
 552                 return;
 553         }
 554
 555         // Dismiss the entry for origin_sample so that back() gives us the
 556         // real last entry
 557         edges->pop_back();
 558         dest.push_back(edges->back());
 559         edges->clear();
 560
 561         // Get first edge to the right of origin_sample
 562         get_subsampled_edges(*edges, origin_sample, sample_count_, min_length, sig_index, true);
 563
 564         // "first only" is specified, so nothing needs to be dismissed
 565         if (edges->size() == 0) {
 566                 delete edges;
 567                 return;
 568         }
 569
 570         dest.push_back(edges->front());
 571
 572         delete edges;
 573 }
 574
 575 void LogicSegment::reallocate_mipmap_level(MipMapLevel &m)
 576 {
 577         lock_guard<recursive_mutex> lock(mutex_);
 578
 579         const uint64_t new_data_length = ((m.length + MipMapDataUnit - 1) /
 580                 MipMapDataUnit) * MipMapDataUnit;
 581
 582         if (new_data_length > m.data_length) {
 583                 m.data_length = new_data_length;
 584
 585                 // Padding is added to allow for the uint64_t write word
 586                 m.data = realloc(m.data, new_data_length * unit_size_ +
 587                         sizeof(uint64_t));
 588         }
 589 }
 590
 591 void LogicSegment::append_payload_to_mipmap()
 592 {
 593         MipMapLevel &m0 = mip_map_[0];
 594         uint64_t prev_length;
 595         uint8_t *dest_ptr;
 596         SegmentDataIterator* it;
 597         uint64_t accumulator;
 598         unsigned int diff_counter;
 599
 600         // Expand the data buffer to fit the new samples
 601         prev_length = m0.length;
 602         m0.length = sample_count_ / MipMapScaleFactor;
 603
 604         // Break off if there are no new samples to compute
 605         if (m0.length == prev_length)
 606                 return;
 607
 608         reallocate_mipmap_level(m0);
 609
 610         dest_ptr = (uint8_t*)m0.data + prev_length * unit_size_;
 611
 612         // Iterate through the samples to populate the first level mipmap
 613         const uint64_t start_sample = prev_length * MipMapScaleFactor;
 614         const uint64_t end_sample = m0.length * MipMapScaleFactor;
 615         uint64_t len_sample = end_sample - start_sample;
 616         it = begin_sample_iteration(start_sample);
 617         while (len_sample > 0) {
 618                 // Number of samples available in this chunk
 619                 uint64_t count = get_iterator_valid_length(it);
 620                 // Reduce if less than asked for
 621                 count = std::min(count, len_sample);
 622                 uint8_t *src_ptr = get_iterator_value(it);
 623                 // Submit these contiguous samples to downsampling in bulk
 624                 if (unit_size_ == 1)
 625                         downsampleT<uint8_t>(src_ptr, dest_ptr, count);
 626                 else if (unit_size_ == 2)
 627                         downsampleT<uint16_t>(src_ptr, dest_ptr, count);
 628                 else if (unit_size_ == 4)
 629                         downsampleT<uint32_t>(src_ptr, dest_ptr, count);
 630                 else if (unit_size_ == 8)
 631                         downsampleT<uint8_t>(src_ptr, dest_ptr, count);
 632                 else
 633                         downsampleGeneric(src_ptr, dest_ptr, count);
 634                 len_sample -= count;
 635                 // Advance iterator, should move to start of next chunk
 636                 continue_sample_iteration(it, count);
 637         }
 638         end_sample_iteration(it);
 639
 640         // Compute higher level mipmaps
 641         for (unsigned int level = 1; level < ScaleStepCount; level++) {
 642                 MipMapLevel &m = mip_map_[level];
 643                 const MipMapLevel &ml = mip_map_[level - 1];
 644
 645                 // Expand the data buffer to fit the new samples
 646                 prev_length = m.length;
 647                 m.length = ml.length / MipMapScaleFactor;
 648
 649                 // Break off if there are no more samples to be computed
 650                 if (m.length == prev_length)
 651                         break;
 652
 653                 reallocate_mipmap_level(m);
 654
 655                 // Subsample the lower level
 656                 const uint8_t* src_ptr = (uint8_t*)ml.data +
 657                         unit_size_ * prev_length * MipMapScaleFactor;
 658                 const uint8_t *const end_dest_ptr =
 659                         (uint8_t*)m.data + unit_size_ * m.length;
 660
 661                 for (dest_ptr = (uint8_t*)m.data +
 662                                 unit_size_ * prev_length;
 663                                 dest_ptr < end_dest_ptr;
 664                                 dest_ptr += unit_size_) {
 665                         accumulator = 0;
 666                         diff_counter = MipMapScaleFactor;
 667                         while (diff_counter-- > 0) {
 668                                 accumulator |= unpack_sample(src_ptr);
 669                                 src_ptr += unit_size_;
 670                         }
 671
 672                         pack_sample(dest_ptr, accumulator);
 673                 }
 674         }
 675 }
 676
 677 uint64_t LogicSegment::get_unpacked_sample(uint64_t index) const
 678 {
 679         assert(index < sample_count_);
 680
 681         assert(unit_size_ <= 8);  // 8 * 8 = 64 channels
 682         uint8_t data[8];
 683
 684         get_raw_samples(index, 1, data);
 685
 686         return unpack_sample(data);
 687 }
 688
 689 uint64_t LogicSegment::get_subsample(int level, uint64_t offset) const
 690 {
 691         assert(level >= 0);
 692         assert(mip_map_[level].data);
 693         return unpack_sample((uint8_t*)mip_map_[level].data +
 694                 unit_size_ * offset);
 695 }
 696
 697 uint64_t LogicSegment::pow2_ceil(uint64_t x, unsigned int power)
 698 {
 699         const uint64_t p = UINT64_C(1) << power;
 700         return (x + p - 1) / p * p;
 701 }
 702
 703 } // namespace data
 704 } // namespace pv