pv/data/analogsnapshot.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, 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 <stdlib.h>
  26 #include <math.h>
  27
  28 #include <algorithm>
  29
  30 #include <boost/foreach.hpp>
  31
  32 #include "analogsnapshot.h"
  33
  34 using boost::lock_guard;
  35 using boost::recursive_mutex;
  36 using std::max;
  37 using std::max_element;
  38 using std::min;
  39 using std::min_element;
  40
  41 namespace pv {
  42 namespace data {
  43
  44 const int AnalogSnapshot::EnvelopeScalePower = 4;
  45 const int AnalogSnapshot::EnvelopeScaleFactor = 1 << EnvelopeScalePower;
  46 const float AnalogSnapshot::LogEnvelopeScaleFactor =
  47         logf(EnvelopeScaleFactor);
  48 const uint64_t AnalogSnapshot::EnvelopeDataUnit = 64*1024;      // bytes
  49
  50 AnalogSnapshot::AnalogSnapshot(const sr_datafeed_analog &analog) :
  51         Snapshot(sizeof(float))
  52 {
  53         lock_guard<recursive_mutex> lock(_mutex);
  54         memset(_envelope_levels, 0, sizeof(_envelope_levels));
  55         append_payload(analog);
  56 }
  57
  58 AnalogSnapshot::~AnalogSnapshot()
  59 {
  60         lock_guard<recursive_mutex> lock(_mutex);
  61         BOOST_FOREACH(Envelope &e, _envelope_levels)
  62                 free(e.samples);
  63 }
  64
  65 void AnalogSnapshot::append_payload(
  66         const sr_datafeed_analog &analog)
  67 {
  68         lock_guard<recursive_mutex> lock(_mutex);
  69         append_data(analog.data, analog.num_samples);
  70
  71         // Generate the first mip-map from the data
  72         append_payload_to_envelope_levels();
  73 }
  74
  75 const float* AnalogSnapshot::get_samples(
  76         int64_t start_sample, int64_t end_sample) const
  77 {
  78         assert(start_sample >= 0);
  79         assert(start_sample < (int64_t)_sample_count);
  80         assert(end_sample >= 0);
  81         assert(end_sample < (int64_t)_sample_count);
  82         assert(start_sample <= end_sample);
  83
  84         lock_guard<recursive_mutex> lock(_mutex);
  85
  86         float *const data = new float[end_sample - start_sample];
  87         memcpy(data, (float*)_data + start_sample, sizeof(float) *
  88                 (end_sample - start_sample));
  89         return data;
  90 }
  91
  92 void AnalogSnapshot::get_envelope_section(EnvelopeSection &s,
  93         uint64_t start, uint64_t end, float min_length) const
  94 {
  95         assert(end <= get_sample_count());
  96         assert(start <= end);
  97         assert(min_length > 0);
  98
  99         lock_guard<recursive_mutex> lock(_mutex);
 100
 101         const unsigned int min_level = max((int)floorf(logf(min_length) /
 102                 LogEnvelopeScaleFactor) - 1, 0);
 103         const unsigned int scale_power = (min_level + 1) *
 104                 EnvelopeScalePower;
 105         start >>= scale_power;
 106         end >>= scale_power;
 107
 108         s.start = start << scale_power;
 109         s.scale = 1 << scale_power;
 110         s.length = end - start;
 111         s.samples = new EnvelopeSample[s.length];
 112         memcpy(s.samples, _envelope_levels[min_level].samples + start,
 113                 s.length * sizeof(EnvelopeSample));
 114 }
 115
 116 void AnalogSnapshot::reallocate_envelope(Envelope &e)
 117 {
 118         const uint64_t new_data_length = ((e.length + EnvelopeDataUnit - 1) /
 119                 EnvelopeDataUnit) * EnvelopeDataUnit;
 120         if (new_data_length > e.data_length)
 121         {
 122                 e.data_length = new_data_length;
 123                 e.samples = (EnvelopeSample*)realloc(e.samples,
 124                         new_data_length * sizeof(EnvelopeSample));
 125         }
 126 }
 127
 128 void AnalogSnapshot::append_payload_to_envelope_levels()
 129 {
 130         Envelope &e0 = _envelope_levels[0];
 131         uint64_t prev_length;
 132         EnvelopeSample *dest_ptr;
 133
 134         // Expand the data buffer to fit the new samples
 135         prev_length = e0.length;
 136         e0.length = _sample_count / EnvelopeScaleFactor;
 137
 138         // Break off if there are no new samples to compute
 139         if (e0.length == prev_length)
 140                 return;
 141
 142         reallocate_envelope(e0);
 143
 144         dest_ptr = e0.samples + prev_length;
 145
 146         // Iterate through the samples to populate the first level mipmap
 147         const float *const end_src_ptr = (float*)_data +
 148                 e0.length * EnvelopeScaleFactor;
 149         for (const float *src_ptr = (float*)_data +
 150                 prev_length * EnvelopeScaleFactor;
 151                 src_ptr < end_src_ptr; src_ptr += EnvelopeScaleFactor)
 152         {
 153                 const EnvelopeSample sub_sample = {
 154                         *min_element(src_ptr, src_ptr + EnvelopeScaleFactor),
 155                         *max_element(src_ptr, src_ptr + EnvelopeScaleFactor),
 156                 };
 157
 158                 *dest_ptr++ = sub_sample;
 159         }
 160
 161         // Compute higher level mipmaps
 162         for (unsigned int level = 1; level < ScaleStepCount; level++)
 163         {
 164                 Envelope &e = _envelope_levels[level];
 165                 const Envelope &el = _envelope_levels[level-1];
 166
 167                 // Expand the data buffer to fit the new samples
 168                 prev_length = e.length;
 169                 e.length = el.length / EnvelopeScaleFactor;
 170
 171                 // Break off if there are no more samples to computed
 172                 if (e.length == prev_length)
 173                         break;
 174
 175                 reallocate_envelope(e);
 176
 177                 // Subsample the level lower level
 178                 const EnvelopeSample *src_ptr =
 179                         el.samples + prev_length * EnvelopeScaleFactor;
 180                 const EnvelopeSample *const end_dest_ptr = e.samples + e.length;
 181                 for (dest_ptr = e.samples + prev_length;
 182                         dest_ptr < end_dest_ptr; dest_ptr++)
 183                 {
 184                         const EnvelopeSample *const end_src_ptr =
 185                                 src_ptr + EnvelopeScaleFactor;
 186
 187                         EnvelopeSample sub_sample = *src_ptr++;
 188                         while (src_ptr < end_src_ptr)
 189                         {
 190                                 sub_sample.min = min(sub_sample.min, src_ptr->min);
 191                                 sub_sample.max = max(sub_sample.max, src_ptr->max);
 192                                 src_ptr++;
 193                         }
 194
 195                         *dest_ptr = sub_sample;
 196                 }
 197         }
 198 }
 199
 200 } // namespace data
 201 } // namespace pv