BladeRF output: set FIFO size to 0.25s or 75 kS whichever is larger (300kS/s knee) except when decimating by 32 where a fixed 150 kS FIFO is used

devices/bladerf/CMakeLists.txt

@@ -3,12 +3,14 @@ project(bladerfdevice)
 set(bladerfdevice_SOURCES
     devicebladerf.cpp
     devicebladerfvalues.cpp
+    devicebladerfshared.cpp
 )
 
 set(bladerfdevice_HEADERS
     devicebladerf.h
     devicebladerfvalues.h
     devicebladerfparam.h
+    devicebladerfshared.h
 )
 
 if (BUILD_DEBIAN)

devices/bladerf/devicebladerfshared.cpp

@@ -0,0 +1,21 @@
+///////////////////////////////////////////////////////////////////////////////////
+// Copyright (C) 2017 Edouard Griffiths, F4EXB                                   //
+//                                                                               //
+// This program is free software; you can redistribute it and/or modify          //
+// it under the terms of the GNU General Public License as published by          //
+// the Free Software Foundation as version 3 of the License, or                  //
+//                                                                               //
+// This program is distributed in the hope that it will be useful,               //
+// but WITHOUT ANY WARRANTY; without even the implied warranty of                //
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the                  //
+// GNU General Public License V3 for more details.                               //
+//                                                                               //
+// You should have received a copy of the GNU General Public License             //
+// along with this program. If not, see <http://www.gnu.org/licenses/>.          //
+///////////////////////////////////////////////////////////////////////////////////
+
+#include "devicebladerfshared.h"
+
+const float  DeviceBladeRFShared::m_sampleFifoLengthInSeconds = 0.25;
+const int    DeviceBladeRFShared::m_sampleFifoMinSize = 75000; // 300 kS/s knee
+const int    DeviceBladeRFShared::m_sampleFifoMinSize32 = 150000; // Fixed for interpolation by 32

devices/bladerf/devicebladerfshared.h

@@ -0,0 +1,31 @@
+///////////////////////////////////////////////////////////////////////////////////
+// Copyright (C) 2017 Edouard Griffiths, F4EXB                                   //
+//                                                                               //
+// This program is free software; you can redistribute it and/or modify          //
+// it under the terms of the GNU General Public License as published by          //
+// the Free Software Foundation as version 3 of the License, or                  //
+//                                                                               //
+// This program is distributed in the hope that it will be useful,               //
+// but WITHOUT ANY WARRANTY; without even the implied warranty of                //
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the                  //
+// GNU General Public License V3 for more details.                               //
+//                                                                               //
+// You should have received a copy of the GNU General Public License             //
+// along with this program. If not, see <http://www.gnu.org/licenses/>.          //
+///////////////////////////////////////////////////////////////////////////////////
+
+#ifndef DEVICES_BLADERF_DEVICEHACKRFSHARED_H_
+#define DEVICES_BLADERF_DEVICEHACKRFSHARED_H_
+
+#include "util/message.h"
+
+class DeviceBladeRFShared
+{
+public:
+    static const float  m_sampleFifoLengthInSeconds;
+    static const int    m_sampleFifoMinSize;
+    static const int    m_sampleFifoMinSize32;
+};
+
+
+#endif /* DEVICES_BLADERF_DEVICEHACKRFSHARED_H_ */

devices/devices.pro

@@ -45,7 +45,8 @@ CONFIG(Release):build_subdir = release
 CONFIG(Debug):build_subdir = debug
 
 !macx:SOURCES += bladerf/devicebladerf.cpp\
-        bladerf/devicebladerfvalues.cpp
+        bladerf/devicebladerfvalues.cpp\
+        bladerf/devicebladerfshared.cpp
 
 SOURCES += hackrf/devicehackrf.cpp\
         hackrf/devicehackrfvalues.cpp\
@@ -57,7 +58,8 @@ CONFIG(MINGW64)SOURCES += limesdr/devicelimesdr.cpp\
 
 !macx:HEADERS -= bladerf/devicebladerf.h\
         bladerf/devicebladerfparam.h\
-        bladerf/devicebladerfvalues.h
+        bladerf/devicebladerfvalues.h\
+        bladerf/devicebladerfshared.h
 
 HEADERS  += hackrf/devicehackrf.h\
         hackrf/devicehackrfparam.h\

plugins/samplesink/bladerfoutput/bladerfoutput.cpp

@@ -23,6 +23,7 @@
 #include "dsp/dspengine.h"
 #include "device/devicesinkapi.h"
 #include "device/devicesourceapi.h"
+#include "bladerf/devicebladerfshared.h"
 
 #include "bladerfoutput.h"
 #include "bladerfoutputgui.h"
@@ -243,10 +244,20 @@ bool BladerfOutput::applySettings(const BladeRFOutputSettings& settings, bool fo
 
 	if ((m_settings.m_devSampleRate != settings.m_devSampleRate) || (m_settings.m_log2Interp != settings.m_log2Interp) || force)
 	{
-	    // FIFO size:
+	    int fifoSize;
-	    // 1 s length up to interpolation by 16
+
-	    // 2 s for interpolation by 32
+	    if (settings.m_log2Interp == 5)
-	    m_sampleSourceFifo.resize(settings.m_devSampleRate/(1<<(settings.m_log2Interp <= 4 ? settings.m_log2Interp : 4)));
+	    {
+	        fifoSize = DeviceBladeRFShared::m_sampleFifoMinSize32;
+	    }
+	    else
+	    {
+	        fifoSize = std::max(
+	            (int) ((settings.m_devSampleRate/(1<<settings.m_log2Interp)) * DeviceBladeRFShared::m_sampleFifoLengthInSeconds),
+	            DeviceBladeRFShared::m_sampleFifoMinSize);
+	    }
+
+        m_sampleSourceFifo.resize(fifoSize);
 	}
 
     if ((m_settings.m_devSampleRate != settings.m_devSampleRate) || force)