Added subsampling for fast lookup

[pulseview.git] / logicdatasnapshot.cpp

diff --git a/logicdatasnapshot.cpp b/logicdatasnapshot.cpp
index e29a866e5fea444b735e5219835c1278b746bef5..8f7e9922bb50b3ccf74815d2c2200b00fbefe329 100644 (file)
--- a/logicdatasnapshot.cpp
+++ b/logicdatasnapshot.cpp
@@ -18,25 +18,142 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  */
 
-#include "logicdatasnapshot.h"
+#include "extdef.h"
 
 #include <assert.h>
+#include <string.h>
+#include <math.h>
+
+#include <boost/foreach.hpp>
+
+#include "logicdatasnapshot.h"
 
 using namespace std;
 
+const int LogicDataSnapshot::MipMapScalePower = 4;
+const int LogicDataSnapshot::MipMapScaleFactor = 1 << MipMapScalePower;
+const uint64_t LogicDataSnapshot::MipMapDataUnit = 64*1024;    // bytes
+
 LogicDataSnapshot::LogicDataSnapshot(
        const sr_datafeed_logic &logic) :
-       DataSnapshot(logic.unitsize)
+       DataSnapshot(logic.unitsize),
+       _last_append_sample(0)
 {
+       memset(_mip_map, 0, sizeof(_mip_map));
        append_payload(logic);
 }
 
+LogicDataSnapshot::~LogicDataSnapshot()
+{
+       BOOST_FOREACH(MipMapLevel &l, _mip_map)
+               free(l.data);
+}
+
 void LogicDataSnapshot::append_payload(
        const sr_datafeed_logic &logic)
 {
        assert(_unit_size == logic.unitsize);
 
+       const uint64_t prev_length = _data_length;
        append_data(logic.data, logic.length);
+
+       // 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 = _data_length / 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