ngscopeclient · Jul 23, 2020
diff --git a/scopehal/CMakeLists.txt b/scopehal/CMakeLists.txt
@@ -29,6 +29,8 @@ set(SCOPEHAL_SOURCES
 	SCPITMCTransport.cpp
 	SCPIDevice.cpp
 
+	TouchstoneParser.cpp
+
 	Instrument.cpp
 	FunctionGenerator.cpp
 	Oscilloscope.cpp

diff --git a/scopehal/TouchstoneParser.cpp b/scopehal/TouchstoneParser.cpp
@@ -0,0 +1,198 @@
+/***********************************************************************************************************************
+*                                                                                                                      *
+* ANTIKERNEL v0.1                                                                                                      *
+*                                                                                                                      *
+* Copyright (c) 2012-2020 Andrew D. Zonenberg                                                                          *
+* All rights reserved.                                                                                                 *
+*                                                                                                                      *
+* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the     *
+* following conditions are met:                                                                                        *
+*                                                                                                                      *
+*    * Redistributions of source code must retain the above copyright notice, this list of conditions, and the         *
+*      following disclaimer.                                                                                           *
+*                                                                                                                      *
+*    * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the       *
+*      following disclaimer in the documentation and/or other materials provided with the distribution.                *
+*                                                                                                                      *
+*    * Neither the name of the author nor the names of any contributors may be used to endorse or promote products     *
+*      derived from this software without specific prior written permission.                                           *
+*                                                                                                                      *
+* THIS SOFTWARE IS PROVIDED BY THE AUTHORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED   *
+* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL *
+* THE AUTHORS BE HELD LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES        *
+* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR       *
+* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT *
+* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE       *
+* POSSIBILITY OF SUCH DAMAGE.                                                                                          *
+*                                                                                                                      *
+***********************************************************************************************************************/
+
+/**
+	@file
+	@author Andrew D. Zonenberg
+	@brief Implementation of TouchstoneParser
+ */
+#include "scopehal.h"
+
+using namespace std;
+
+////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+// SParameterVector
+
+SParameterPoint SParameterVector::InterpolatePoint(float frequency)
+{
+	//Binary search to find the points straddling us
+	size_t len = m_points.size();
+	size_t pos = len/2;
+	size_t last_lo = 0;
+	size_t last_hi = len - 1;
+	while(true)
+	{
+		SParameterPoint pivot = m_points[pos];
+
+		//Dead on? Stop
+		if( (last_hi - last_lo) <= 1)
+			break;
+
+		//Too high, move down
+		if(pivot.m_frequency > frequency)
+		{
+			size_t delta = (pos - last_lo);
+			pos = last_lo + delta/2;
+			last_hi = pos;
+		}
+
+		//Too low, move up
+		else
+		{
+			size_t delta = last_hi - pos;
+			pos = last_hi - delta/2;
+			last_lo = pos;
+		}
+	}
+
+	//Find position between the points for interpolation
+	float freq_lo = m_points[last_lo].m_frequency;
+	float freq_hi = m_points[last_hi].m_frequency;
+	float dfreq = freq_hi - freq_lo;
+	float frac = (frequency - freq_lo) / dfreq;
+
+	//Interpolate amplitude
+	SParameterPoint ret;
+	float amp_lo = m_points[last_lo].m_amplitude;
+	float amp_hi = m_points[last_hi].m_amplitude;
+	ret.m_amplitude = amp_lo + (amp_hi - amp_lo)*frac;
+
+	//TODO: figure out phase. For now leave it at zero (i.e. don't de-embed phase, just do scalar amplitude correction)
+	ret.m_phase = 0;
+
+	ret.m_frequency = frequency;
+	return ret;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+// TouchstoneParser
+
+TouchstoneParser::TouchstoneParser()
+{
+}
+
+TouchstoneParser::~TouchstoneParser()
+{
+	Clear();
+}
+
+/**
+	@brief Clears out current S-parameters before reloading them
+ */
+void TouchstoneParser::Clear()
+{
+	for(auto it : m_params)
+		delete it.second;
+	m_params.clear();
+}
+
+/**
+	@brief Loads the file
+ */
+bool TouchstoneParser::Load(string fname)
+{
+	Clear();
+
+	//Allocate new arrays to hold the S-parameters.
+	//For now, assume full 2 port.
+	for(int d=1; d <= 2; d++)
+	{
+		for(int s=1; s <= 2; s++)
+			m_params[SPair(d, s)] = new SParameterVector;
+	}
+
+	//If file doesn't exist, bail early
+	FILE* fp = fopen(fname.c_str(), "r");
+	if(!fp)
+	{
+		LogError("Unable to open S-parameter file %s\n", fname.c_str());
+		return false;
+	}
+
+	//Read line by line.
+	char line[256];
+	while(!feof(fp))
+	{
+		fgets(line, sizeof(line), fp);
+
+		//Comments start with a !
+		if(line[0] == '!')
+			continue;
+
+		//Header line with metadata starts with a #
+		if(line[0] == '#')
+		{
+			//Format: # [freq unit] S [MA|DB] R [impedance]
+			char freq_unit[32];
+			char volt_unit[32];
+			int impedance;
+			if(3 != sscanf(line, "# %31s S %31s R %d", freq_unit, volt_unit, &impedance))
+			{
+				LogError("Failed to parse S2P header line \"%s\"\n", line);
+				return false;
+			}
+
+			//Figure out units
+			if(0 != strcmp(freq_unit, "MHZ"))
+			{
+				LogError("S2P frequency units other than MHZ not yet supported (got %s)\n", freq_unit);
+				return false;
+			}
+			if(0 != strcmp(volt_unit, "MA"))
+			{
+				LogError("S2P voltage units other than MA not yet supported (got %s)\n", volt_unit);
+				return false;
+			}
+
+			continue;
+		}
+
+		//Each S2P line is formatted as freq s11 s21 s12 s22
+		float mhz, s11m, s11p, s21m, s21p, s12m, s12p, s22m, s22p;
+		if(9 != sscanf(line, "%f %f %f %f %f %f %f %f %f", &mhz, &s11m, &s11p, &s21m, &s21p, &s12m, &s12p, &s22m, &s22p))
+		{
+			LogError("Malformed S2P line \"%s\"", line);
+			return false;
+		}
+
+		//Save everything
+		float hz = mhz * 1e6;
+		m_params[SPair(1,1)]->m_points.push_back(SParameterPoint(hz, s11m, s11p));
+		m_params[SPair(2,1)]->m_points.push_back(SParameterPoint(hz, s21m, s21p));
+		m_params[SPair(1,2)]->m_points.push_back(SParameterPoint(hz, s12m, s12p));
+		m_params[SPair(2,2)]->m_points.push_back(SParameterPoint(hz, s22m, s22p));
+	}
+
+	//Clean up
+	fclose(fp);
+
+	LogDebug("Loaded %zu S-parameter points\n", m_params[SPair(2,1)]->m_points.size());
+
+	return true;
+}
diff --git a/scopehal/TouchstoneParser.h b/scopehal/TouchstoneParser.h
@@ -0,0 +1,96 @@
+/***********************************************************************************************************************
+*                                                                                                                      *
+* ANTIKERNEL v0.1                                                                                                      *
+*                                                                                                                      *
+* Copyright (c) 2012-2020 Andrew D. Zonenberg                                                                          *
+* All rights reserved.                                                                                                 *
+*                                                                                                                      *
+* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the     *
+* following conditions are met:                                                                                        *
+*                                                                                                                      *
+*    * Redistributions of source code must retain the above copyright notice, this list of conditions, and the         *
+*      following disclaimer.                                                                                           *
+*                                                                                                                      *
+*    * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the       *
+*      following disclaimer in the documentation and/or other materials provided with the distribution.                *
+*                                                                                                                      *
+*    * Neither the name of the author nor the names of any contributors may be used to endorse or promote products     *
+*      derived from this software without specific prior written permission.                                           *
+*                                                                                                                      *
+* THIS SOFTWARE IS PROVIDED BY THE AUTHORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED   *
+* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL *
+* THE AUTHORS BE HELD LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES        *
+* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR       *
+* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT *
+* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE       *
+* POSSIBILITY OF SUCH DAMAGE.                                                                                          *
+*                                                                                                                      *
+***********************************************************************************************************************/
+
+/**
+	@file
+	@author Andrew D. Zonenberg
+	@brief Declaration of TouchstoneParser
+ */
+
+#ifndef TouchstoneParser_h
+#define TouchstoneParser_h
+
+/**
+	@brief A single point in an S-parameter dataset
+ */
+class SParameterPoint
+{
+public:
+	SParameterPoint()
+	{}
+
+	SParameterPoint(float f, float a, float p)
+	: m_frequency(f)
+	, m_amplitude(a)
+	, m_phase(p)
+	{
+	}
+
+	float	m_frequency;	//Hz
+	float	m_amplitude;	//magnitude
+	float	m_phase;		//radians
+};
+
+/**
+	@brief A single S-parameter array
+ */
+class SParameterVector
+{
+public:
+
+	SParameterPoint InterpolatePoint(float frequency);
+
+	std::vector<SParameterPoint> m_points;
+};
+
+/**
+	@brief Touchstone (SxP) file parser
+ */
+class TouchstoneParser
+{
+public:
+	TouchstoneParser();
+	virtual ~TouchstoneParser();
+
+	void Clear();
+	bool Load(std::string fname);
+
+	typedef std::pair<int, int> SPair;
+
+	/**
+		@brief Sample a single point from a single S-parameter
+	 */
+	SParameterPoint SamplePoint(int to, int from, float frequency)
+	{ return m_params[ SPair(to, from) ]->InterpolatePoint(frequency); }
+
+protected:
+	std::map< SPair , SParameterVector*> m_params;
+};
+
+#endif
diff --git a/scopehal/scopehal.h b/scopehal/scopehal.h
@@ -54,6 +54,8 @@
 #include "Bijection.h"
 #include "IDTable.h"
 
+#include "TouchstoneParser.h"
+
 #include "SCPITransport.h"
 #include "SCPISocketTransport.h"
 #include "SCPILxiTransport.h"

diff --git a/scopeprotocols/CMakeLists.txt b/scopeprotocols/CMakeLists.txt
@@ -11,6 +11,7 @@ set(SCOPEPROTOCOLS_SOURCES
 	CurrentShuntDecoder.cpp
 	DCOffsetDecoder.cpp
 	DDR3Decoder.cpp
+	DeEmbedDecoder.cpp
 	DeskewDecoder.cpp
 	DifferenceDecoder.cpp
 	DramRefreshActivateMeasurementDecoder.cpp