Added decimation class with unsigned to signed conversion with shift. Applied to RTL-SDR

plugins/samplesource/rtlsdr/rtlsdrthread.cpp

@@ -88,7 +88,7 @@ void RTLSDRThread::run()
 }
 
 //  Decimate according to specified log2 (ex: log2=4 => decim=16)
-void RTLSDRThread::callback(const qint8* buf, qint32 len)
+void RTLSDRThread::callback(const quint8* buf, qint32 len)
 {
 	SampleVector::iterator it = m_convertBuffer.begin();
 
@@ -178,9 +178,6 @@ void RTLSDRThread::callback(const qint8* buf, qint32 len)
 void RTLSDRThread::callbackHelper(unsigned char* buf, uint32_t len, void* ctx)
 {
 	RTLSDRThread* thread = (RTLSDRThread*)ctx;
-	for (unsigned int i = 0; i < len; i++) {
-	    buf[i] = buf[i] - 127;
-	}
-	thread->callback((qint8 *) buf, len);
+	thread->callback(buf, len);
 }
 

plugins/samplesource/rtlsdr/rtlsdrthread.h

@@ -24,7 +24,7 @@
 #include <rtl-sdr.h>
 
 #include "dsp/samplesinkfifo.h"
-#include "dsp/decimators.h"
+#include "dsp/decimatorsu.h"
 
 class RTLSDRThread : public QThread {
 	Q_OBJECT
@@ -52,10 +52,10 @@ private:
 	unsigned int m_log2Decim;
 	int m_fcPos;
 
-	Decimators<qint8, SDR_SAMP_SZ, 8> m_decimators;
+	DecimatorsU<quint8, SDR_SAMP_SZ, 8, 127> m_decimators;
 
 	void run();
-	void callback(const qint8* buf, qint32 len);
+	void callback(const quint8* buf, qint32 len);
 
 	static void callbackHelper(unsigned char* buf, uint32_t len, void* ctx);
 };

sdrbase/CMakeLists.txt

@@ -96,6 +96,7 @@ set(sdrbase_HEADERS
     dsp/cwkeyer.h
     dsp/cwkeyersettings.h
     dsp/decimators.h
+    dsp/decimatorsu.h
     dsp/interpolators.h
     dsp/dspcommands.h
     dsp/dspengine.h