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
  67         for (MipMapLevel &l : mip_map_)
  68                 free(l.data);
  69 }
  70
  71 shared_ptr<const LogicSegment> LogicSegment::get_shared_ptr() const
  72 {
  73         shared_ptr<const Segment> ptr = nullptr;
  74
  75         try {
  76                 ptr = shared_from_this();
  77         } catch (std::exception& e) {
  78                 /* Do nothing, ptr remains a null pointer */
  79         }
  80
  81         return ptr ? std::dynamic_pointer_cast<const LogicSegment>(ptr) : nullptr;
  82 }
  83
  84 template <class T>
  85 void LogicSegment::downsampleTmain(const T*&in, T &acc, T &prev)
  86 {
  87         // Accumulate one sample at a time
  88         for (uint64_t i = 0; i < MipMapScaleFactor; i++) {
  89                 T sample = *in++;
  90                 acc |= prev ^ sample;
  91                 prev = sample;
  92         }
  93 }
  94
  95 template <>
  96 void LogicSegment::downsampleTmain<uint8_t>(const uint8_t*&in, uint8_t &acc, uint8_t &prev)
  97 {
  98         // Handle 8 bit samples in 32 bit steps
  99         uint32_t prev32 = prev | prev << 8 | prev << 16 | prev << 24;
 100         uint32_t acc32 = acc;
 101         const uint32_t *in32 = (const uint32_t*)in;
 102         for (uint64_t i = 0; i < MipMapScaleFactor; i += 4) {
 103                 uint32_t sample32 = *in32++;
 104                 acc32 |= prev32 ^ sample32;
 105                 prev32 = sample32;
 106         }
 107         // Reduce result back to uint8_t
 108 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 109         prev = (prev32 >> 24) & 0xff; // MSB is last
 110 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
 111         prev = prev32 & 0xff; // LSB is last
 112 #else
 113 #error Endianness unknown
 114 #endif
 115         acc |= acc32 & 0xff;
 116         acc |= (acc32 >> 8) & 0xff;
 117         acc |= (acc32 >> 16) & 0xff;
 118         acc |= (acc32 >> 24) & 0xff;
 119         in = (const uint8_t*)in32;
 120 }
 121
 122 template <>
 123 void LogicSegment::downsampleTmain<uint16_t>(const uint16_t*&in, uint16_t &acc, uint16_t &prev)
 124 {
 125         // Handle 16 bit samples in 32 bit steps
 126         uint32_t prev32 = prev | prev << 16;
 127         uint32_t acc32 = acc;
 128         const uint32_t *in32 = (const uint32_t*)in;
 129         for (uint64_t i = 0; i < MipMapScaleFactor; i += 2) {
 130                 uint32_t sample32 = *in32++;
 131                 acc32 |= prev32 ^ sample32;
 132                 prev32 = sample32;
 133         }
 134         // Reduce result back to uint16_t
 135 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 136         prev = (prev32 >> 16) & 0xffff; // MSB is last
 137 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
 138         prev = prev32 & 0xffff; // LSB is last
 139 #else
 140 #error Endian unknown
 141 #endif
 142         acc |= acc32 & 0xffff;
 143         acc |= (acc32 >> 16) & 0xffff;
 144         in = (const uint16_t*)in32;
 145 }
 146
 147 template <class T>
 148 void LogicSegment::downsampleT(const uint8_t *in_, uint8_t *&out_, uint64_t len)
 149 {
 150         const T *in = (const T*)in_;
 151         T *out = (T*)out_;
 152         T prev = last_append_sample_;
 153         T acc = last_append_accumulator_;
 154
 155         // Try to complete the previous downsample
 156         if (last_append_extra_) {
 157                 while (last_append_extra_ < MipMapScaleFactor && len > 0) {
 158                         T sample = *in++;
 159                         acc |= prev ^ sample;
 160                         prev = sample;
 161                         last_append_extra_++;
 162                         len--;
 163                 }
 164                 if (!len) {
 165                         // Not enough samples available to complete downsample
 166                         last_append_sample_ = prev;
 167                         last_append_accumulator_ = acc;
 168                         return;
 169                 }
 170                 // We have a complete downsample
 171                 *out++ = acc;
 172                 acc = 0;
 173                 last_append_extra_ = 0;
 174         }
 175
 176         // Handle complete blocks of MipMapScaleFactor samples
 177         while (len >= MipMapScaleFactor) {
 178                 downsampleTmain<T>(in, acc, prev);
 179                 len -= MipMapScaleFactor;
 180                 // Output downsample
 181                 *out++ = acc;
 182                 acc = 0;
 183         }
 184
 185         // Process remainder, not enough for a complete sample
 186         while (len > 0) {
 187                 T sample = *in++;
 188                 acc |= prev ^ sample;
 189                 prev = sample;
 190                 last_append_extra_++;
 191                 len--;
 192         }
 193
 194         // Update context
 195         last_append_sample_ = prev;
 196         last_append_accumulator_ = acc;
 197         out_ = (uint8_t *)out;
 198 }
 199
 200 void LogicSegment::downsampleGeneric(const uint8_t *in, uint8_t *&out, uint64_t len)
 201 {
 202         // Downsample using the generic unpack_sample()
 203         // which can handle any width between 1 and 8 bytes
 204         uint64_t prev = last_append_sample_;
 205         uint64_t acc = last_append_accumulator_;
 206
 207         // Try to complete the previous downsample
 208         if (last_append_extra_) {
 209                 while (last_append_extra_ < MipMapScaleFactor && len > 0) {
 210                         const uint64_t sample = unpack_sample(in);
 211                         in += unit_size_;
 212                         acc |= prev ^ sample;
 213                         prev = sample;
 214                         last_append_extra_++;
 215                         len--;
 216                 }
 217                 if (!len) {
 218                         // Not enough samples available to complete downsample
 219                         last_append_sample_ = prev;
 220                         last_append_accumulator_ = acc;
 221                         return;
 222                 }
 223                 // We have a complete downsample
 224                 pack_sample(out, acc);
 225                 out += unit_size_;
 226                 acc = 0;
 227                 last_append_extra_ = 0;
 228         }
 229
 230         // Handle complete blocks of MipMapScaleFactor samples
 231         while (len >= MipMapScaleFactor) {
 232                 // Accumulate one sample at a time
 233                 for (uint64_t i = 0; i < MipMapScaleFactor; i++) {
 234                         const uint64_t sample = unpack_sample(in);
 235                         in += unit_size_;
 236                         acc |= prev ^ sample;
 237                         prev = sample;
 238                 }
 239                 len -= MipMapScaleFactor;
 240                 // Output downsample
 241                 pack_sample(out, acc);
 242                 out += unit_size_;
 243                 acc = 0;
 244         }
 245
 246         // Process remainder, not enough for a complete sample
 247         while (len > 0) {
 248                 const uint64_t sample = unpack_sample(in);
 249                 in += unit_size_;
 250                 acc |= prev ^ sample;
 251                 prev = sample;
 252                 last_append_extra_++;
 253                 len--;
 254         }
 255
 256         // Update context
 257         last_append_sample_ = prev;
 258         last_append_accumulator_ = acc;
 259 }
 260
 261 inline uint64_t LogicSegment::unpack_sample(const uint8_t *ptr) const
 262 {
 263 #ifdef HAVE_UNALIGNED_LITTLE_ENDIAN_ACCESS
 264         return *(uint64_t*)ptr;
 265 #else
 266         uint64_t value = 0;
 267         switch (unit_size_) {
 268         default:
 269                 value |= ((uint64_t)ptr[7]) << 56;
 270                 /* FALLTHRU */
 271         case 7:
 272                 value |= ((uint64_t)ptr[6]) << 48;
 273                 /* FALLTHRU */
 274         case 6:
 275                 value |= ((uint64_t)ptr[5]) << 40;
 276                 /* FALLTHRU */
 277         case 5:
 278                 value |= ((uint64_t)ptr[4]) << 32;
 279                 /* FALLTHRU */
 280         case 4:
 281                 value |= ((uint32_t)ptr[3]) << 24;
 282                 /* FALLTHRU */
 283         case 3:
 284                 value |= ((uint32_t)ptr[2]) << 16;
 285                 /* FALLTHRU */
 286         case 2:
 287                 value |= ptr[1] << 8;
 288                 /* FALLTHRU */
 289         case 1:
 290                 value |= ptr[0];
 291                 /* FALLTHRU */
 292         case 0:
 293                 break;
 294         }
 295         return value;
 296 #endif
 297 }
 298
 299 inline void LogicSegment::pack_sample(uint8_t *ptr, uint64_t value)
 300 {
 301 #ifdef HAVE_UNALIGNED_LITTLE_ENDIAN_ACCESS
 302         *(uint64_t*)ptr = value;
 303 #else
 304         switch (unit_size_) {
 305         default:
 306                 ptr[7] = value >> 56;
 307                 /* FALLTHRU */
 308         case 7:
 309                 ptr[6] = value >> 48;
 310                 /* FALLTHRU */
 311         case 6:
 312                 ptr[5] = value >> 40;
 313                 /* FALLTHRU */
 314         case 5:
 315                 ptr[4] = value >> 32;
 316                 /* FALLTHRU */
 317         case 4:
 318                 ptr[3] = value >> 24;
 319                 /* FALLTHRU */
 320         case 3:
 321                 ptr[2] = value >> 16;
 322                 /* FALLTHRU */
 323         case 2:
 324                 ptr[1] = value >> 8;
 325                 /* FALLTHRU */
 326         case 1:
 327                 ptr[0] = value;
 328                 /* FALLTHRU */
 329         case 0:
 330                 break;
 331         }
 332 #endif
 333 }
 334
 335 void LogicSegment::append_payload(shared_ptr<sigrok::Logic> logic)
 336 {
 337         assert(unit_size_ == logic->unit_size());
 338         assert((logic->data_length() % unit_size_) == 0);
 339
 340         append_payload(logic->data_pointer(), logic->data_length());
 341 }
 342
 343 void LogicSegment::append_payload(void *data, uint64_t data_size)
 344 {
 345         assert(unit_size_ > 0);
 346         assert((data_size % unit_size_) == 0);
 347
 348         lock_guard<recursive_mutex> lock(mutex_);
 349
 350         const uint64_t prev_sample_count = sample_count_;
 351         const uint64_t sample_count = data_size / unit_size_;
 352
 353         append_samples(data, sample_count);
 354
 355         // Generate the first mip-map from the data
 356         append_payload_to_mipmap();
 357
 358         if (sample_count > 1)
 359                 owner_.notify_samples_added(SharedPtrToSegment(shared_from_this()),
 360                         prev_sample_count + 1, prev_sample_count + 1 + sample_count);
 361         else
 362                 owner_.notify_samples_added(SharedPtrToSegment(shared_from_this()),
 363                         prev_sample_count + 1, prev_sample_count + 1);
 364 }
 365
 366 void LogicSegment::append_subsignal_payload(unsigned int index, void *data, uint64_t data_size)
 367 {
 368         static vector<uint8_t> merged_data;  // To preserve intermediate data across calls
 369
 370         if (index == 0)
 371                 for (uint64_t i = 0; i < data_size * unit_size_; i++)
 372                         merged_data.emplace_back(0);
 373
 374         // Set the bits for this sub-signal where needed
 375         // Note: the bytes in *data must either be 0 or 1, nothing else
 376         unsigned int index_byte_offs = index / 8;
 377         uint8_t* output_data = merged_data.data() + index_byte_offs;
 378         uint8_t* input_data = (uint8_t*)data;
 379
 380         for (uint64_t i = 0; i < data_size; i++) {
 381                 assert((i * unit_size_ + index_byte_offs) < merged_data.size());
 382                 *output_data |= (input_data[i] << index);
 383                 output_data += unit_size_;
 384         }
 385
 386         if (index == owner_.num_channels() - 1) {
 387                 // We gathered sample data of all sub-signals, let's append it
 388                 append_payload(merged_data.data(), merged_data.size());
 389                 merged_data.clear();
 390         }
 391 }
 392
 393 void LogicSegment::get_samples(int64_t start_sample,
 394         int64_t end_sample, uint8_t* dest) const
 395 {
 396         assert(start_sample >= 0);
 397         assert(start_sample <= (int64_t)sample_count_);
 398         assert(end_sample >= 0);
 399         assert(end_sample <= (int64_t)sample_count_);
 400         assert(start_sample <= end_sample);
 401         assert(dest != nullptr);
 402
 403         lock_guard<recursive_mutex> lock(mutex_);
 404
 405         get_raw_samples(start_sample, (end_sample - start_sample), dest);
 406 }
 407
 408 void LogicSegment::get_subsampled_edges(
 409         vector<EdgePair> &edges,
 410         uint64_t start, uint64_t end,
 411         float min_length, int sig_index, bool first_change_only)
 412 {
 413         uint64_t index = start;
 414         unsigned int level;
 415         bool last_sample;
 416         bool fast_forward;
 417
 418         assert(start <= end);
 419         assert(min_length > 0);
 420         assert(sig_index >= 0);
 421         assert(sig_index < 64);
 422
 423         lock_guard<recursive_mutex> lock(mutex_);
 424
 425         // Make sure we only process as many samples as we have
 426         if (end > get_sample_count())
 427                 end = get_sample_count();
 428
 429         const uint64_t block_length = (uint64_t)max(min_length, 1.0f);
 430         const unsigned int min_level = max((int)floorf(logf(min_length) /
 431                 LogMipMapScaleFactor) - 1, 0);
 432         const uint64_t sig_mask = 1ULL << sig_index;
 433
 434         // Store the initial state
 435         last_sample = (get_unpacked_sample(start) & sig_mask) != 0;
 436         if (!first_change_only)
 437                 edges.emplace_back(index++, last_sample);
 438
 439         while (index + block_length <= end) {
 440                 //----- Continue to search -----//
 441                 level = min_level;
 442
 443                 // We cannot fast-forward if there is no mip-map data at
 444                 // the minimum level.
 445                 fast_forward = (mip_map_[level].data != nullptr);
 446
 447                 if (min_length < MipMapScaleFactor) {
 448                         // Search individual samples up to the beginning of
 449                         // the next first level mip map block
 450                         const uint64_t final_index = min(end, pow2_ceil(index, MipMapScalePower));
 451
 452                         for (; index < final_index &&
 453                                         (index & ~((uint64_t)(~0) << MipMapScalePower)) != 0;
 454                                         index++) {
 455
 456                                 const bool sample = (get_unpacked_sample(index) & sig_mask) != 0;
 457
 458                                 // If there was a change we cannot fast forward
 459                                 if (sample != last_sample) {
 460                                         fast_forward = false;
 461                                         break;
 462                                 }
 463                         }
 464                 } else {
 465                         // If resolution is less than a mip map block,
 466                         // round up to the beginning of the mip-map block
 467                         // for this level of detail
 468                         const int min_level_scale_power = (level + 1) * MipMapScalePower;
 469                         index = pow2_ceil(index, min_level_scale_power);
 470                         if (index >= end)
 471                                 break;
 472
 473                         // We can fast forward only if there was no change
 474                         const bool sample = (get_unpacked_sample(index) & sig_mask) != 0;
 475                         if (last_sample != sample)
 476                                 fast_forward = false;
 477                 }
 478
 479                 if (fast_forward) {
 480
 481                         // Fast forward: This involves zooming out to higher
 482                         // levels of the mip map searching for changes, then
 483                         // zooming in on them to find the point where the edge
 484                         // begins.
 485
 486                         // Slide right and zoom out at the beginnings of mip-map
 487                         // blocks until we encounter a change
 488                         while (true) {
 489                                 const int level_scale_power = (level + 1) * MipMapScalePower;
 490                                 const uint64_t offset = index >> level_scale_power;
 491
 492                                 // Check if we reached the last block at this
 493                                 // level, or if there was a change in this block
 494                                 if (offset >= mip_map_[level].length ||
 495                                         (get_subsample(level, offset) & sig_mask))
 496                                         break;
 497
 498                                 if ((offset & ~((uint64_t)(~0) << MipMapScalePower)) == 0) {
 499                                         // If we are now at the beginning of a
 500                                         // higher level mip-map block ascend one
 501                                         // level
 502                                         if ((level + 1 >= ScaleStepCount) || (!mip_map_[level + 1].data))
 503                                                 break;
 504
 505                                         level++;
 506                                 } else {
 507                                         // Slide right to the beginning of the
 508                                         // next mip map block
 509                                         index = pow2_ceil(index + 1, level_scale_power);
 510                                 }
 511                         }
 512
 513                         // Zoom in, and slide right until we encounter a change,
 514                         // and repeat until we reach min_level
 515                         while (true) {
 516                                 assert(mip_map_[level].data);
 517
 518                                 const int level_scale_power = (level + 1) * MipMapScalePower;
 519                                 const uint64_t offset = index >> level_scale_power;
 520
 521                                 // Check if we reached the last block at this
 522                                 // level, or if there was a change in this block
 523                                 if (offset >= mip_map_[level].length ||
 524                                                 (get_subsample(level, offset) & sig_mask)) {
 525                                         // Zoom in unless we reached the minimum
 526                                         // zoom
 527                                         if (level == min_level)
 528                                                 break;
 529
 530                                         level--;
 531                                 } else {
 532                                         // Slide right to the beginning of the
 533                                         // next mip map block
 534                                         index = pow2_ceil(index + 1, level_scale_power);
 535                                 }
 536                         }
 537
 538                         // If individual samples within the limit of resolution,
 539                         // do a linear search for the next transition within the
 540                         // block
 541                         if (min_length < MipMapScaleFactor) {
 542                                 for (; index < end; index++) {
 543                                         const bool sample = (get_unpacked_sample(index) & sig_mask) != 0;
 544                                         if (sample != last_sample)
 545                                                 break;
 546                                 }
 547                         }
 548                 }
 549
 550                 //----- Store the edge -----//
 551
 552                 // Take the last sample of the quanization block
 553                 const int64_t final_index = index + block_length;
 554                 if (index + block_length > end)
 555                         break;
 556
 557                 // Store the final state
 558                 const bool final_sample = (get_unpacked_sample(final_index - 1) & sig_mask) != 0;
 559                 edges.emplace_back(index, final_sample);
 560
 561                 index = final_index;
 562                 last_sample = final_sample;
 563
 564                 if (first_change_only)
 565                         break;
 566         }
 567
 568         // Add the final state
 569         if (!first_change_only) {
 570                 const bool end_sample = get_unpacked_sample(end) & sig_mask;
 571                 if (last_sample != end_sample)
 572                         edges.emplace_back(end, end_sample);
 573                 edges.emplace_back(end + 1, end_sample);
 574         }
 575 }
 576
 577 void LogicSegment::get_surrounding_edges(vector<EdgePair> &dest,
 578         uint64_t origin_sample, float min_length, int sig_index)
 579 {
 580         if (origin_sample >= sample_count_)
 581                 return;
 582
 583         // Put the edges vector on the heap, it can become quite big until we can
 584         // use a get_subsampled_edges() implementation that searches backwards
 585         vector<EdgePair>* edges = new vector<EdgePair>;
 586
 587         // Get all edges to the left of origin_sample
 588         get_subsampled_edges(*edges, 0, origin_sample, min_length, sig_index, false);
 589
 590         // If we don't specify "first only", the first and last edge are the states
 591         // at samples 0 and origin_sample. If only those exist, there are no edges
 592         if (edges->size() == 2) {
 593                 delete edges;
 594                 return;
 595         }
 596
 597         // Dismiss the entry for origin_sample so that back() gives us the
 598         // real last entry
 599         edges->pop_back();
 600         dest.push_back(edges->back());
 601         edges->clear();
 602
 603         // Get first edge to the right of origin_sample
 604         get_subsampled_edges(*edges, origin_sample, sample_count_, min_length, sig_index, true);
 605
 606         // "first only" is specified, so nothing needs to be dismissed
 607         if (edges->size() == 0) {
 608                 delete edges;
 609                 return;
 610         }
 611
 612         dest.push_back(edges->front());
 613
 614         delete edges;
 615 }
 616
 617 void LogicSegment::reallocate_mipmap_level(MipMapLevel &m)
 618 {
 619         lock_guard<recursive_mutex> lock(mutex_);
 620
 621         const uint64_t new_data_length = ((m.length + MipMapDataUnit - 1) /
 622                 MipMapDataUnit) * MipMapDataUnit;
 623
 624         if (new_data_length > m.data_length) {
 625                 m.data_length = new_data_length;
 626
 627                 // Padding is added to allow for the uint64_t write word
 628                 m.data = realloc(m.data, new_data_length * unit_size_ +
 629                         sizeof(uint64_t));
 630         }
 631 }
 632
 633 void LogicSegment::append_payload_to_mipmap()
 634 {
 635         MipMapLevel &m0 = mip_map_[0];
 636         uint64_t prev_length;
 637         uint8_t *dest_ptr;
 638         SegmentDataIterator* it;
 639         uint64_t accumulator;
 640         unsigned int diff_counter;
 641
 642         // Expand the data buffer to fit the new samples
 643         prev_length = m0.length;
 644         m0.length = sample_count_ / MipMapScaleFactor;
 645
 646         // Break off if there are no new samples to compute
 647         if (m0.length == prev_length)
 648                 return;
 649
 650         reallocate_mipmap_level(m0);
 651
 652         dest_ptr = (uint8_t*)m0.data + prev_length * unit_size_;
 653
 654         // Iterate through the samples to populate the first level mipmap
 655         const uint64_t start_sample = prev_length * MipMapScaleFactor;
 656         const uint64_t end_sample = m0.length * MipMapScaleFactor;
 657         uint64_t len_sample = end_sample - start_sample;
 658         it = begin_sample_iteration(start_sample);
 659         while (len_sample > 0) {
 660                 // Number of samples available in this chunk
 661                 uint64_t count = get_iterator_valid_length(it);
 662                 // Reduce if less than asked for
 663                 count = std::min(count, len_sample);
 664                 uint8_t *src_ptr = get_iterator_value(it);
 665                 // Submit these contiguous samples to downsampling in bulk
 666                 if (unit_size_ == 1)
 667                         downsampleT<uint8_t>(src_ptr, dest_ptr, count);
 668                 else if (unit_size_ == 2)
 669                         downsampleT<uint16_t>(src_ptr, dest_ptr, count);
 670                 else if (unit_size_ == 4)
 671                         downsampleT<uint32_t>(src_ptr, dest_ptr, count);
 672                 else if (unit_size_ == 8)
 673                         downsampleT<uint64_t>(src_ptr, dest_ptr, count);
 674                 else
 675                         downsampleGeneric(src_ptr, dest_ptr, count);
 676                 len_sample -= count;
 677                 // Advance iterator, should move to start of next chunk
 678                 continue_sample_iteration(it, count);
 679         }
 680         end_sample_iteration(it);
 681
 682         // Compute higher level mipmaps
 683         for (unsigned int level = 1; level < ScaleStepCount; level++) {
 684                 MipMapLevel &m = mip_map_[level];
 685                 const MipMapLevel &ml = mip_map_[level - 1];
 686
 687                 // Expand the data buffer to fit the new samples
 688                 prev_length = m.length;
 689                 m.length = ml.length / MipMapScaleFactor;
 690
 691                 // Break off if there are no more samples to be computed
 692                 if (m.length == prev_length)
 693                         break;
 694
 695                 reallocate_mipmap_level(m);
 696
 697                 // Subsample the lower level
 698                 const uint8_t* src_ptr = (uint8_t*)ml.data +
 699                         unit_size_ * prev_length * MipMapScaleFactor;
 700                 const uint8_t *const end_dest_ptr =
 701                         (uint8_t*)m.data + unit_size_ * m.length;
 702
 703                 for (dest_ptr = (uint8_t*)m.data +
 704                                 unit_size_ * prev_length;
 705                                 dest_ptr < end_dest_ptr;
 706                                 dest_ptr += unit_size_) {
 707                         accumulator = 0;
 708                         diff_counter = MipMapScaleFactor;
 709                         while (diff_counter-- > 0) {
 710                                 accumulator |= unpack_sample(src_ptr);
 711                                 src_ptr += unit_size_;
 712                         }
 713
 714                         pack_sample(dest_ptr, accumulator);
 715                 }
 716         }
 717 }
 718
 719 uint64_t LogicSegment::get_unpacked_sample(uint64_t index) const
 720 {
 721         assert(index < sample_count_);
 722
 723         assert(unit_size_ <= 8);  // 8 * 8 = 64 channels
 724         uint8_t data[8];
 725
 726         get_raw_samples(index, 1, data);
 727
 728         return unpack_sample(data);
 729 }
 730
 731 uint64_t LogicSegment::get_subsample(int level, uint64_t offset) const
 732 {
 733         assert(level >= 0);
 734         assert(mip_map_[level].data);
 735         return unpack_sample((uint8_t*)mip_map_[level].data +
 736                 unit_size_ * offset);
 737 }
 738
 739 uint64_t LogicSegment::pow2_ceil(uint64_t x, unsigned int power)
 740 {
 741         const uint64_t p = UINT64_C(1) << power;
 742         return (x + p - 1) / p * p;
 743 }
 744
 745 } // namespace data
 746 } // namespace pv