Added code to construct analog envelope levels

diff --git a/pv/data/analogsnapshot.cpp b/pv/data/analogsnapshot.cpp
index 1658a04c3bfe365138b5ba21f064702e3719e0f7..c052782ed6cc6842f5029c80b6de3223ee76d50c 100644 (file)
--- a/pv/data/analogsnapshot.cpp
+++ b/pv/data/analogsnapshot.cpp
@@ -25,6 +25,8 @@
 #include <stdlib.h>
 #include <math.h>
 
+#include <algorithm>
+
 #include <boost/foreach.hpp>
 
 #include "analogsnapshot.h"
@@ -35,18 +37,35 @@ using namespace std;
 namespace pv {
 namespace data {
 
+const int AnalogSnapshot::EnvelopeScalePower = 4;
+const int AnalogSnapshot::EnvelopeScaleFactor = 1 << EnvelopeScalePower;
+const float AnalogSnapshot::LogEnvelopeScaleFactor =
+       logf(EnvelopeScaleFactor);
+const uint64_t AnalogSnapshot::EnvelopeDataUnit = 64*1024;     // bytes
+
 AnalogSnapshot::AnalogSnapshot(const sr_datafeed_analog &analog) :
        Snapshot(sizeof(float))
 {
        lock_guard<recursive_mutex> lock(_mutex);
+       memset(_envelope_levels, 0, sizeof(_envelope_levels));
        append_payload(analog);
 }
 
+AnalogSnapshot::~AnalogSnapshot()
+{
+       lock_guard<recursive_mutex> lock(_mutex);
+       BOOST_FOREACH(Envelope &e, _envelope_levels)
+               free(e.samples);
+}
+
 void AnalogSnapshot::append_payload(
        const sr_datafeed_analog &analog)
 {
        lock_guard<recursive_mutex> lock(_mutex);
        append_data(analog.data, analog.num_samples);
+
+       // Generate the first mip-map from the data
+       append_payload_to_envelope_levels();
 }
 
 const float* AnalogSnapshot::get_samples(
@@ -66,5 +85,89 @@ const float* AnalogSnapshot::get_samples(
        return data;
 }
 
+void AnalogSnapshot::reallocate_envelope(Envelope &e)
+{
+       const uint64_t new_data_length = ((e.length + EnvelopeDataUnit - 1) /
+               EnvelopeDataUnit) * EnvelopeDataUnit;
+       if (new_data_length > e.data_length)
+       {
+               e.data_length = new_data_length;
+               e.samples = (EnvelopeSample*)realloc(e.samples,
+                       new_data_length * sizeof(EnvelopeSample));
+       }
+}
+
+void AnalogSnapshot::append_payload_to_envelope_levels()
+{
+       Envelope &e0 = _envelope_levels[0];
+       uint64_t prev_length;
+       EnvelopeSample *dest_ptr;
+
+       // Expand the data buffer to fit the new samples
+       prev_length = e0.length;
+       e0.length = _sample_count / EnvelopeScaleFactor;
+
+       // Break off if there are no new samples to compute
+       if (e0.length == prev_length)
+               return;
+
+       reallocate_envelope(e0);
+
+       dest_ptr = e0.samples + prev_length;
+
+       // Iterate through the samples to populate the first level mipmap
+       const float *const end_src_ptr = (float*)_data +
+               e0.length * EnvelopeScaleFactor;
+       for (const float *src_ptr = (float*)_data +
+               prev_length * EnvelopeScaleFactor;
+               src_ptr < end_src_ptr; src_ptr += EnvelopeScaleFactor)
+       {
+               const EnvelopeSample sub_sample = {
+                       *min_element(src_ptr, src_ptr + EnvelopeScaleFactor),
+                       *max_element(src_ptr, src_ptr + EnvelopeScaleFactor),
+               };
+
+               *dest_ptr++ = sub_sample;
+       }
+
+       // Compute higher level mipmaps
+       for (unsigned int level = 1; level < ScaleStepCount; level++)
+       {
+               Envelope &e = _envelope_levels[level];
+               const Envelope &el = _envelope_levels[level-1];
+
+               // Expand the data buffer to fit the new samples
+               prev_length = e.length;
+               e.length = el.length / EnvelopeScaleFactor;
+
+               // Break off if there are no more samples to computed
+               if (e.length == prev_length)
+                       break;
+
+               reallocate_envelope(e);
+
+               // Subsample the level lower level
+               const EnvelopeSample *src_ptr =
+                       el.samples + prev_length * EnvelopeScaleFactor;
+               const EnvelopeSample *const end_dest_ptr = e.samples + e.length;
+               for (dest_ptr = e.samples + prev_length;
+                       dest_ptr < end_dest_ptr; dest_ptr++)
+               {
+                       const EnvelopeSample *const end_src_ptr =
+                               src_ptr + EnvelopeScaleFactor;
+
+                       EnvelopeSample sub_sample = *src_ptr++;
+                       while (src_ptr < end_src_ptr)
+                       {
+                               sub_sample.min = min(sub_sample.min, src_ptr->min);
+                               sub_sample.max = max(sub_sample.max, src_ptr->max);
+                               src_ptr++;
+                       }
+
+                       *dest_ptr = sub_sample;
+               }
+       }
+}
+
 } // namespace data
 } // namespace pv

diff --git a/pv/data/analogsnapshot.h b/pv/data/analogsnapshot.h
index a45391849220332b892faa9ed3eaa79df30a4df6..8eec2797f1a4aa77b5945ccf31f2eef926600dce 100644 (file)
--- a/pv/data/analogsnapshot.h
+++ b/pv/data/analogsnapshot.h
@@ -31,15 +31,44 @@ namespace data {
 
 class AnalogSnapshot : public Snapshot
 {
+private:
+       struct EnvelopeSample
+       {
+               float min;
+               float max;
+       };
+
+       struct Envelope
+       {
+               uint64_t length;
+               uint64_t data_length;
+               EnvelopeSample *samples;
+       };
+
+private:
+       static const unsigned int ScaleStepCount = 10;
+       static const int EnvelopeScalePower;
+       static const int EnvelopeScaleFactor;
+       static const float LogEnvelopeScaleFactor;
+       static const uint64_t EnvelopeDataUnit;
+
 public:
        AnalogSnapshot(const sr_datafeed_analog &analog);
 
+       virtual ~AnalogSnapshot();
+
        void append_payload(const sr_datafeed_analog &analog);
 
        const float* get_samples(int64_t start_sample,
                int64_t end_sample) const;
-};
 
+private:
+       void reallocate_envelope(Envelope &l);
+
+       void append_payload_to_envelope_levels();
+
+private:
+       struct Envelope _envelope_levels[ScaleStepCount];
 } // namespace data
 } // namespace pv