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