+
+ // Generate the first mip-map from the data
+ append_payload_to_mipmap();
+}
+
+void LogicDataSnapshot::reallocate_mip_map(MipMapLevel &m)
+{
+ const uint64_t new_data_length = ((m.length + MipMapDataUnit - 1) /
+ MipMapDataUnit) * MipMapDataUnit;
+ if(new_data_length > m.data_length)
+ {
+ m.data_length = new_data_length;
+ m.data = realloc(m.data, new_data_length * _unit_size);
+ }
+}
+
+void LogicDataSnapshot::append_payload_to_mipmap()
+{
+ MipMapLevel &m0 = _mip_map[0];
+ uint64_t prev_length;
+ const uint8_t *src_ptr;
+ uint8_t *dest_ptr;
+ uint64_t accumulator;
+ unsigned int diff_counter;
+
+ // Expand the data buffer to fit the new samples
+ prev_length = m0.length;
+ m0.length = _sample_count / MipMapScaleFactor;
+
+ // Break off if there are no new samples to compute
+ if(m0.length == prev_length)
+ return;
+
+ reallocate_mip_map(m0);
+
+ dest_ptr = (uint8_t*)m0.data + prev_length * _unit_size;
+
+ // Iterate through the samples to populate the first level mipmap
+ accumulator = 0;
+ diff_counter = MipMapScaleFactor;
+ const uint8_t *end_src_ptr = (uint8_t*)_data +
+ m0.length * _unit_size * MipMapScaleFactor;
+ for(src_ptr = (uint8_t*)_data +
+ prev_length * _unit_size * MipMapScaleFactor;
+ src_ptr < end_src_ptr;)
+ {
+ // Accumulate transitions which have occurred in this sample
+ accumulator = 0;
+ diff_counter = MipMapScaleFactor;
+ while(diff_counter-- > 0)
+ {
+ const uint64_t sample = *(uint64_t*)src_ptr;
+ accumulator |= _last_append_sample ^ sample;
+ _last_append_sample = sample;
+ src_ptr += _unit_size;
+ }
+
+ *(uint64_t*)dest_ptr = accumulator;
+ dest_ptr += _unit_size;
+ }
+
+ // Compute higher level mipmaps
+ for(int level = 1; level < ScaleStepCount; level++)
+ {
+ MipMapLevel &m = _mip_map[level];
+ const MipMapLevel &ml = _mip_map[level-1];
+
+ // Expand the data buffer to fit the new samples
+ prev_length = m.length;
+ m.length = ml.length / MipMapScaleFactor;
+
+ // Break off if there are no more samples to computed
+ if(m.length == prev_length)
+ break;
+
+ reallocate_mip_map(m);
+
+ // Subsample the level lower level
+ src_ptr = (uint8_t*)ml.data +
+ _unit_size * prev_length * MipMapScaleFactor;
+ const uint8_t *end_dest_ptr =
+ (uint8_t*)m.data + _unit_size * m.length;
+ for(dest_ptr = (uint8_t*)m.data +
+ _unit_size * prev_length;
+ dest_ptr < end_dest_ptr;
+ dest_ptr += _unit_size)
+ {
+ accumulator = 0;
+ diff_counter = MipMapScaleFactor;
+ while(diff_counter-- > 0)
+ {
+ accumulator |= *(uint64_t*)src_ptr;
+ src_ptr += _unit_size;
+ }
+
+ *(uint64_t*)dest_ptr = accumulator;
+ }
+ }
+}
+
+uint64_t LogicDataSnapshot::get_sample(uint64_t index) const
+{
+ assert(_data);
+ assert(index >= 0 && index < _sample_count);
+
+ return *(uint64_t*)((uint8_t*)_data + index * _unit_size);
+}
+
+void LogicDataSnapshot::get_subsampled_edges(
+ std::vector<EdgePair> &edges,
+ int64_t start, int64_t end,
+ float min_length, int sig_index)
+{
+ int64_t index = start;
+ int level;
+ bool last_sample;
+ bool fast_forward;
+
+ assert(start >= 0);
+ assert(end <= get_sample_count());
+ assert(start <= end);
+ assert(min_length > 0);
+ assert(sig_index >= 0);
+ assert(sig_index < SR_MAX_NUM_PROBES);
+
+ const int64_t block_length = (int64_t)max(min_length, 1.0f);
+ const int min_level = max((int)floorf(logf(min_length) /
+ LogMipMapScaleFactor) - 1, 0);
+ const uint64_t sig_mask = 1ULL << sig_index;
+
+ // Store the initial state
+ last_sample = (get_sample(start) & sig_mask) != 0;
+ edges.push_back(pair<int64_t, bool>(index++, last_sample));
+
+ while(index + block_length <= end)
+ {
+ //----- Continue to search -----//
+ level = min_level;
+ fast_forward = true;
+
+ if(min_length < MipMapScaleFactor)
+ {
+ // Search individual samples up to the beginning of
+ // the next first level mip map block
+ const uint64_t final_index = min(end,
+ pow2_ceil(index, MipMapScalePower));
+
+ for(index;
+ index < final_index &&
+ (index & ~(~0 << MipMapScalePower)) != 0;
+ index++)
+ {
+ const bool sample =
+ (get_sample(index) & sig_mask) != 0;
+
+ // If there was a change we cannot fast forward
+ if(sample != last_sample) {
+ fast_forward = false;
+ break;
+ }
+ }
+ }
+ else
+ {
+ // If resolution is less than a mip map block,
+ // round up to the beginning of the mip-map block
+ // for this level of detail
+ const int min_level_scale_power =
+ (level + 1) * MipMapScalePower;
+ index = pow2_ceil(index, min_level_scale_power);
+ if(index >= end)
+ break;
+
+ // We can fast forward only if there was no change
+ const bool sample =
+ (get_sample(index) & sig_mask) != 0;
+ fast_forward = last_sample == sample;
+ }
+
+ if(fast_forward) {
+
+ // Fast forward: This involves zooming out to higher
+ // levels of the mip map searching for changes, then
+ // zooming in on them to find the point where the edge
+ // begins.
+
+ // Slide right and zoom out at the beginnings of mip-map
+ // blocks until we encounter a change
+ while(1) {
+ const int level_scale_power =
+ (level + 1) * MipMapScalePower;
+ const uint64_t offset =
+ index >> level_scale_power;
+ assert(offset >= 0);
+
+ // Check if we reached the last block at this
+ // level, or if there was a change in this block
+ if(offset >= _mip_map[level].length ||
+ (get_subsample(level, offset) &
+ sig_mask))
+ break;
+
+ if((offset & ~(~0 << MipMapScalePower)) == 0) {
+ // If we are now at the beginning of a
+ // higher level mip-map block ascend one
+ // level
+ if(level + 1 >= ScaleStepCount ||
+ !_mip_map[level + 1].data)
+ break;
+
+ level++;
+ } else {
+ // Slide right to the beginning of the
+ // next mip map block
+ index = pow2_ceil(index + 1,
+ level_scale_power);
+ }
+ }
+
+ // Zoom in, and slide right until we encounter a change,
+ // and repeat until we reach min_level
+ while(1) {
+ assert(_mip_map[level].data);
+
+ const int level_scale_power =
+ (level + 1) * MipMapScalePower;
+ const uint64_t offset =
+ index >> level_scale_power;
+ assert(offset >= 0);
+
+ // Check if we reached the last block at this
+ // level, or if there was a change in this block
+ if(offset >= _mip_map[level].length ||
+ (get_subsample(level, offset) &
+ sig_mask)) {
+ // Zoom in unless we reached the minimum
+ // zoom
+ if(level == min_level)
+ break;
+
+ level--;
+ } else {
+ // Slide right to the beginning of the
+ // next mip map block
+ index = pow2_ceil(index + 1,
+ level_scale_power);
+ }
+ }
+
+ // If individual samples within the limit of resolution,
+ // do a linear search for the next transition within the
+ // block
+ if(min_length < MipMapScaleFactor) {
+ for(index; index < end; index++) {
+ const bool sample = (get_sample(index) &
+ sig_mask) != 0;
+ if(sample != last_sample)
+ break;
+ }
+ }
+ }
+
+ //----- Store the edge -----//
+
+ // Take the last sample of the quanization block
+ const int64_t final_index = index + block_length;
+ if(index + block_length > end)
+ break;
+
+ // Store the final state
+ const bool final_sample =
+ (get_sample(final_index - 1) & sig_mask) != 0;
+ edges.push_back(pair<int64_t, bool>(index, final_sample));
+
+ index = final_index;
+ last_sample = final_sample;
+ }
+
+ // Add the final state
+ edges.push_back(pair<int64_t, bool>(end,
+ get_sample(end) & sig_mask));
+}
+
+uint64_t LogicDataSnapshot::get_subsample(int level, uint64_t offset) const
+{
+ assert(level >= 0);
+ assert(_mip_map[level].data);
+ return *(uint64_t*)((uint8_t*)_mip_map[level].data +
+ _unit_size * offset);
+}
+
+int64_t LogicDataSnapshot::pow2_ceil(int64_t x, unsigned int power)
+{
+ const int64_t p = 1 << power;
+ return ((x < 0) ? x : (x + p - 1)) / p * p;