From 9b10ddc6685d2e95c1e427ad16c92d61cec6771c Mon Sep 17 00:00:00 2001
From: f4exb <f4exb06@gmail.com>
Date: Sun, 19 Jul 2020 11:48:02 +0200
Subject: [PATCH] Channel Analyzer: use complex decimator for decimation by
 power of two value

---
 .../channelrx/chanalyzer/chanalyzersink.cpp   | 30 +++++++++++++++++--
 plugins/channelrx/chanalyzer/chanalyzersink.h |  2 ++
 2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/plugins/channelrx/chanalyzer/chanalyzersink.cpp b/plugins/channelrx/chanalyzer/chanalyzersink.cpp
index 43295a685..daca343ff 100644
--- a/plugins/channelrx/chanalyzer/chanalyzersink.cpp
+++ b/plugins/channelrx/chanalyzer/chanalyzersink.cpp
@@ -69,10 +69,19 @@ void ChannelAnalyzerSink::feed(const SampleVector::const_iterator& begin, const
 		}
 		else
 		{
-            if (m_interpolator.decimate(&m_interpolatorDistanceRemain, c, &ci))
+            if (m_settings.m_rationalDownSample)
             {
-                processOneSample(ci, sideband);
-                m_interpolatorDistanceRemain += m_interpolatorDistance;
+                if (m_interpolator.decimate(&m_interpolatorDistanceRemain, c, &ci))
+                {
+                    processOneSample(ci, sideband);
+                    m_interpolatorDistanceRemain += m_interpolatorDistance;
+                }
+            }
+            else
+            {
+                if (m_decimator.decimate(c, ci)) {
+                    processOneSample(ci, sideband);
+                }
             }
 		}
 	}
@@ -153,6 +162,21 @@ void ChannelAnalyzerSink::applyChannelSettings(int channelSampleRate, int sinkSa
         setFilters(sinkSampleRate, m_settings.m_bandwidth, m_settings.m_lowCutoff);
         m_pll.setSampleRate(sinkSampleRate);
         m_fll.setSampleRate(sinkSampleRate);
+
+        int decim = channelSampleRate / sinkSampleRate;
+        m_decimator.setLog2Decim(0);
+
+        for (int i = 0; i < 7; i++) // find log2 beween 0 and 6
+        {
+            if (decim & 1 == 1)
+            {
+                qDebug() << "ChannelAnalyzerSink::applyChannelSettings: log2decim: " << i;
+                m_decimator.setLog2Decim(i);
+                break;
+            }
+
+            decim >>= 1;
+        }
     }
 
     m_channelSampleRate = channelSampleRate;
diff --git a/plugins/channelrx/chanalyzer/chanalyzersink.h b/plugins/channelrx/chanalyzer/chanalyzersink.h
index 8014529a6..4f9ca989a 100644
--- a/plugins/channelrx/chanalyzer/chanalyzersink.h
+++ b/plugins/channelrx/chanalyzer/chanalyzersink.h
@@ -20,6 +20,7 @@
 
 #include "dsp/channelsamplesink.h"
 #include "dsp/interpolator.h"
+#include "dsp/decimatorc.h"
 #include "dsp/ncof.h"
 #include "dsp/fftcorr.h"
 #include "dsp/fftfilt.h"
@@ -69,6 +70,7 @@ private:
     Interpolator m_interpolator;
     Real m_interpolatorDistance;
     Real m_interpolatorDistanceRemain;
+    DecimatorC m_decimator;
 
 	fftfilt* SSBFilter;
 	fftfilt* DSBFilter;