logicdatasnapshot.cpp

   1 /*
   2  * This file is part of the sigrok 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, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  19  */
  20
  21 #include "extdef.h"
  22
  23 #include <assert.h>
  24 #include <string.h>
  25 #include <math.h>
  26
  27 #include <boost/foreach.hpp>
  28
  29 #include "logicdatasnapshot.h"
  30
  31 using namespace std;
  32
  33 const int LogicDataSnapshot::MipMapScalePower = 4;
  34 const int LogicDataSnapshot::MipMapScaleFactor = 1 << MipMapScalePower;
  35 const float LogicDataSnapshot::LogMipMapScaleFactor = logf(MipMapScaleFactor);
  36 const uint64_t LogicDataSnapshot::MipMapDataUnit = 64*1024;     // bytes
  37
  38 LogicDataSnapshot::LogicDataSnapshot(
  39         const sr_datafeed_logic &logic) :
  40         DataSnapshot(logic.unitsize),
  41         _last_append_sample(0)
  42 {
  43         memset(_mip_map, 0, sizeof(_mip_map));
  44         append_payload(logic);
  45 }
  46
  47 LogicDataSnapshot::~LogicDataSnapshot()
  48 {
  49         BOOST_FOREACH(MipMapLevel &l, _mip_map)
  50                 free(l.data);
  51 }
  52
  53 void LogicDataSnapshot::append_payload(
  54         const sr_datafeed_logic &logic)
  55 {
  56         assert(_unit_size == logic.unitsize);
  57
  58         append_data(logic.data, logic.length);
  59
  60         // Generate the first mip-map from the data
  61         append_payload_to_mipmap();
  62 }
  63
  64 void LogicDataSnapshot::reallocate_mip_map(MipMapLevel &m)
  65 {
  66         const uint64_t new_data_length = ((m.length + MipMapDataUnit - 1) /
  67                 MipMapDataUnit) * MipMapDataUnit;
  68         if(new_data_length > m.data_length)
  69         {
  70                 m.data_length = new_data_length;
  71                 m.data = realloc(m.data, new_data_length * _unit_size);
  72         }
  73 }
  74
  75 void LogicDataSnapshot::append_payload_to_mipmap()
  76 {
  77         MipMapLevel &m0 = _mip_map[0];
  78         uint64_t prev_length;
  79         const uint8_t *src_ptr;
  80         uint8_t *dest_ptr;
  81         uint64_t accumulator;
  82         unsigned int diff_counter;
  83
  84         // Expand the data buffer to fit the new samples
  85         prev_length = m0.length;
  86         m0.length = _sample_count / MipMapScaleFactor;
  87
  88         // Break off if there are no new samples to compute
  89         if(m0.length == prev_length)
  90                 return;
  91
  92         reallocate_mip_map(m0);
  93
  94         dest_ptr = (uint8_t*)m0.data + prev_length * _unit_size;
  95
  96         // Iterate through the samples to populate the first level mipmap
  97         accumulator = 0;
  98         diff_counter = MipMapScaleFactor;
  99         const uint8_t *end_src_ptr = (uint8_t*)_data +
 100                 m0.length * _unit_size * MipMapScaleFactor;
 101         for(src_ptr = (uint8_t*)_data +
 102                 prev_length * _unit_size * MipMapScaleFactor;
 103                 src_ptr < end_src_ptr;)
 104         {
 105                 // Accumulate transitions which have occurred in this sample
 106                 accumulator = 0;
 107                 diff_counter = MipMapScaleFactor;
 108                 while(diff_counter-- > 0)
 109                 {
 110                         const uint64_t sample = *(uint64_t*)src_ptr;
 111                         accumulator |= _last_append_sample ^ sample;
 112                         _last_append_sample = sample;
 113                         src_ptr += _unit_size;
 114                 }
 115
 116                 *(uint64_t*)dest_ptr = accumulator;
 117                 dest_ptr += _unit_size;
 118         }
 119
 120         // Compute higher level mipmaps
 121         for(int level = 1; level < ScaleStepCount; level++)
 122         {
 123                 MipMapLevel &m = _mip_map[level];
 124                 const MipMapLevel &ml = _mip_map[level-1];
 125
 126                 // Expand the data buffer to fit the new samples
 127                 prev_length = m.length;
 128                 m.length = ml.length / MipMapScaleFactor;
 129
 130                 // Break off if there are no more samples to computed
 131                 if(m.length == prev_length)
 132                         break;
 133
 134                 reallocate_mip_map(m);
 135
 136                 // Subsample the level lower level
 137                 src_ptr = (uint8_t*)ml.data +
 138                         _unit_size * prev_length * MipMapScaleFactor;
 139                 const uint8_t *end_dest_ptr =
 140                         (uint8_t*)m.data + _unit_size * m.length;
 141                 for(dest_ptr = (uint8_t*)m.data +
 142                         _unit_size * prev_length;
 143                         dest_ptr < end_dest_ptr;
 144                         dest_ptr += _unit_size)
 145                 {
 146                         accumulator = 0;
 147                         diff_counter = MipMapScaleFactor;
 148                         while(diff_counter-- > 0)
 149                         {
 150                                 accumulator |= *(uint64_t*)src_ptr;
 151                                 src_ptr += _unit_size;
 152                         }
 153
 154                         *(uint64_t*)dest_ptr = accumulator;
 155                 }
 156         }
 157 }
 158
 159 uint64_t LogicDataSnapshot::get_sample(uint64_t index) const
 160 {
 161         assert(_data);
 162         assert(index >= 0 && index < _sample_count);
 163
 164         return *(uint64_t*)((uint8_t*)_data + index * _unit_size);
 165 }
 166
 167 void LogicDataSnapshot::get_subsampled_edges(
 168         std::vector<EdgePair> &edges,
 169         int64_t start, int64_t end,
 170         float min_length, int sig_index)
 171 {
 172         int64_t index = start;
 173         int level;
 174         bool last_sample;
 175         bool fast_forward;
 176
 177         assert(start >= 0);
 178         assert(end <= get_sample_count());
 179         assert(start <= end);
 180         assert(min_length > 0);
 181         assert(sig_index >= 0);
 182         assert(sig_index < SR_MAX_NUM_PROBES);
 183
 184         const int64_t block_length = (int64_t)max(min_length, 1.0f);
 185         const int min_level = max((int)floorf(logf(min_length) /
 186                 LogMipMapScaleFactor) - 1, 0);
 187         const uint64_t sig_mask = 1ULL << sig_index;
 188
 189         // Store the initial state
 190         last_sample = (get_sample(start) & sig_mask) != 0;
 191         edges.push_back(pair<int64_t, bool>(index++, last_sample));
 192
 193         while(index + block_length <= end)
 194         {
 195                 //----- Continue to search -----//
 196                 level = min_level;
 197                 fast_forward = true;
 198
 199                 if(min_length < MipMapScaleFactor)
 200                 {
 201                         // Search individual samples up to the beginning of
 202                         // the next first level mip map block
 203                         const uint64_t final_index = min(end,
 204                                 pow2_ceil(index, MipMapScalePower));
 205
 206                         for(index;
 207                                 index < final_index &&
 208                                 (index & ~(~0 << MipMapScalePower)) != 0;
 209                                 index++)
 210                         {
 211                                 const bool sample =
 212                                         (get_sample(index) & sig_mask) != 0;
 213
 214                                 // If there was a change we cannot fast forward
 215                                 if(sample != last_sample) {
 216                                         fast_forward = false;
 217                                         break;
 218                                 }
 219                         }
 220                 }
 221                 else
 222                 {
 223                         // If resolution is less than a mip map block,
 224                         // round up to the beginning of the mip-map block
 225                         // for this level of detail
 226                         const int min_level_scale_power =
 227                                 (level + 1) * MipMapScalePower;
 228                         index = pow2_ceil(index, min_level_scale_power);
 229                         if(index >= end)
 230                                 break;
 231
 232                         // We can fast forward only if there was no change
 233                         const bool sample =
 234                                 (get_sample(index) & sig_mask) != 0;
 235                         fast_forward = last_sample == sample;
 236                 }
 237
 238                 if(fast_forward) {
 239
 240                         // Fast forward: This involves zooming out to higher
 241                         // levels of the mip map searching for changes, then
 242                         // zooming in on them to find the point where the edge
 243                         // begins.
 244
 245                         // Slide right and zoom out at the beginnings of mip-map
 246                         // blocks until we encounter a change
 247                         while(1) {
 248                                 const int level_scale_power =
 249                                         (level + 1) * MipMapScalePower;
 250                                 const uint64_t offset =
 251                                         index >> level_scale_power;
 252                                 assert(offset >= 0);
 253
 254                                 // Check if we reached the last block at this
 255                                 // level, or if there was a change in this block
 256                                 if(offset >= _mip_map[level].length ||
 257                                         (get_subsample(level, offset) &
 258                                                 sig_mask))
 259                                         break;
 260
 261                                 if((offset & ~(~0 << MipMapScalePower)) == 0) {
 262                                         // If we are now at the beginning of a
 263                                         // higher level mip-map block ascend one
 264                                         // level
 265                                         if(level + 1 >= ScaleStepCount ||
 266                                                 !_mip_map[level + 1].data)
 267                                                 break;
 268
 269                                         level++;
 270                                 } else {
 271                                         // Slide right to the beginning of the
 272                                         // next mip map block
 273                                         index = pow2_ceil(index + 1,
 274                                                 level_scale_power);
 275                                 }
 276                         }
 277
 278                         // Zoom in, and slide right until we encounter a change,
 279                         // and repeat until we reach min_level
 280                         while(1) {
 281                                 assert(_mip_map[level].data);
 282
 283                                 const int level_scale_power =
 284                                         (level + 1) * MipMapScalePower;
 285                                 const uint64_t offset =
 286                                         index >> level_scale_power;
 287                                 assert(offset >= 0);
 288
 289                                 // Check if we reached the last block at this
 290                                 // level, or if there was a change in this block
 291                                 if(offset >= _mip_map[level].length ||
 292                                         (get_subsample(level, offset) &
 293                                                 sig_mask)) {
 294                                         // Zoom in unless we reached the minimum
 295                                         // zoom
 296                                         if(level == min_level)
 297                                                 break;
 298
 299                                         level--;
 300                                 } else {
 301                                         // Slide right to the beginning of the
 302                                         // next mip map block
 303                                         index = pow2_ceil(index + 1,
 304                                                 level_scale_power);
 305                                 }
 306                         }
 307
 308                         // If individual samples within the limit of resolution,
 309                         // do a linear search for the next transition within the
 310                         // block
 311                         if(min_length < MipMapScaleFactor) {
 312                                 for(index; index < end; index++) {
 313                                         const bool sample = (get_sample(index) &
 314                                                 sig_mask) != 0;
 315                                         if(sample != last_sample)
 316                                                 break;
 317                                 }
 318                         }
 319                 }
 320
 321                 //----- Store the edge -----//
 322
 323                 // Take the last sample of the quanization block
 324                 const int64_t final_index = index + block_length;
 325                 if(index + block_length > end)
 326                         break;
 327
 328                 // Store the final state
 329                 const bool final_sample =
 330                         (get_sample(final_index - 1) & sig_mask) != 0;
 331                 edges.push_back(pair<int64_t, bool>(index, final_sample));
 332
 333                 index = final_index;
 334                 last_sample = final_sample;
 335         }
 336
 337         // Add the final state
 338         edges.push_back(pair<int64_t, bool>(end,
 339                 get_sample(end) & sig_mask));
 340 }
 341
 342 uint64_t LogicDataSnapshot::get_subsample(int level, uint64_t offset) const
 343 {
 344         assert(level >= 0);
 345         assert(_mip_map[level].data);
 346         return *(uint64_t*)((uint8_t*)_mip_map[level].data +
 347                 _unit_size * offset);
 348 }
 349
 350 int64_t LogicDataSnapshot::pow2_ceil(int64_t x, unsigned int power)
 351 {
 352         const int64_t p = 1 << power;
 353         return ((x < 0) ? x : (x + p - 1)) / p * p;
 354 }