ngscopeclient · Dec 12, 2020
diff --git a/doc b/doc
diff --git a/lib b/lib
diff --git a/src/glscopeclient/WaveformArea.cpp b/src/glscopeclient/WaveformArea.cpp
@@ -466,10 +466,16 @@ void WaveformArea::on_realize()
 			profile.c_str());
 		{
 			LogIndenter li;
-			LogDebug("GL_VENDOR = %s\n", glGetString(GL_VENDOR));
-			LogDebug("GL_RENDERER = %s\n", glGetString(GL_RENDERER));
-			LogDebug("GL_VERSION = %s\n", glGetString(GL_VERSION));
+			LogDebug("GL_VENDOR                   = %s\n", glGetString(GL_VENDOR));
+			LogDebug("GL_RENDERER                 = %s\n", glGetString(GL_RENDERER));
+			LogDebug("GL_VERSION                  = %s\n", glGetString(GL_VERSION));
 			LogDebug("GL_SHADING_LANGUAGE_VERSION = %s\n", glGetString(GL_SHADING_LANGUAGE_VERSION));
+
+			if(GL_ARB_gpu_shader_int64)
+				LogDebug("GL_ARB_gpu_shader_int64:      supported\n");
+			else
+				LogDebug("GL_ARB_gpu_shader_int64:      not supported\n");
+
 			LogDebug("Initial GL error code: %d\n", glGetError());
 		}
 
@@ -521,13 +527,11 @@ void WaveformArea::on_realize()
 			!GL_EXT_framebuffer_object ||
 			!GL_ARB_vertex_array_object ||
 			!GL_ARB_shader_storage_buffer_object ||
-			!GL_ARB_compute_shader ||
-			!GL_ARB_gpu_shader_int64 )
+			!GL_ARB_compute_shader)
 		{
 			string err =
 				"Your graphics card or driver does not appear to support one or more of the following required extensions:\n"
 				"* GL_ARB_compute_shader\n"
-				"* GL_ARB_gpu_shader_int64\n"
 				"* GL_ARB_shader_storage_buffer_object\n"
 				"* GL_ARB_vertex_array_object\n"
 				"* GL_EXT_blend_equation_separate\n"
@@ -616,23 +620,38 @@ void WaveformArea::CleanupGLHandles()
 
 void WaveformArea::InitializeWaveformPass()
 {
+	//Load all of the compute shaders
 	ComputeShader hwc;
-	if(!hwc.Load("shaders/waveform-compute-histogram.glsl"))
-		LogFatal("failed to load histogram waveform compute shader, aborting\n");
+	ComputeShader dwc;
+	ComputeShader awc;
+	if(GL_ARB_gpu_shader_int64)
+	{
+		if(!hwc.Load("shaders/waveform-compute-histogram.glsl"))
+			LogFatal("failed to load histogram waveform compute shader, aborting\n");
+		if(!dwc.Load("shaders/waveform-compute-digital.glsl"))
+			LogFatal("failed to load digital waveform compute shader, aborting\n");
+		if(!awc.Load("shaders/waveform-compute-analog.glsl"))
+			LogFatal("failed to load analog waveform compute shader, aborting\n");
+	}
+	else
+	{
+		if(!hwc.Load("shaders/waveform-compute-histogram-noint64.glsl"))
+			LogFatal("failed to load histogram waveform compute shader, aborting\n");
+		if(!dwc.Load("shaders/waveform-compute-digital-noint64.glsl"))
+			LogFatal("failed to load digital waveform compute shader, aborting\n");
+		if(!awc.Load("shaders/waveform-compute-analog-noint64.glsl"))
+			LogFatal("failed to load analog waveform compute shader, aborting\n");
+	}
+
+	//Link them
 	m_histogramWaveformComputeProgram.Add(hwc);
 	if(!m_histogramWaveformComputeProgram.Link())
 		LogFatal("failed to link histogram waveform shader program, aborting\n");
 
-	ComputeShader dwc;
-	if(!dwc.Load("shaders/waveform-compute-digital.glsl"))
-		LogFatal("failed to load digital waveform compute shader, aborting\n");
 	m_digitalWaveformComputeProgram.Add(dwc);
 	if(!m_digitalWaveformComputeProgram.Link())
 		LogFatal("failed to link digital waveform shader program, aborting\n");
 
-	ComputeShader awc;
-	if(!awc.Load("shaders/waveform-compute-analog.glsl"))
-		LogFatal("failed to load analog waveform compute shader, aborting\n");
 	m_analogWaveformComputeProgram.Add(awc);
 	if(!m_analogWaveformComputeProgram.Link())
 		LogFatal("failed to link analog waveform shader program, aborting\n");

diff --git a/src/glscopeclient/shaders/waveform-compute-analog-noint64.glsl b/src/glscopeclient/shaders/waveform-compute-analog-noint64.glsl
@@ -0,0 +1,209 @@
+/***********************************************************************************************************************
+*                                                                                                                      *
+* glscopeclient                                                                                                        *
+*                                                                                                                      *
+* 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
+	@brief Waveform rendering shader for analog waveforms without GL_ARB_gpu_shader_int64 support
+ */
+
+#version 430
+
+//The output texture (for now, only alpha channel is used)
+layout(binding=0, rgba32f) uniform image2D outputTex;
+
+layout(std430, binding=1) buffer waveform_x
+{
+	uint xpos[];		//x position, in time ticks
+						//actually 64-bit little endian signed ints
+};
+
+layout(std430, binding=4) buffer waveform_y
+{
+	float voltage[];	//y value of the sample, in volts
+};
+
+//Global configuration for the run
+layout(std430, binding=2) buffer config
+{
+	uint innerXoff_lo;	//actually a 64-bit little endian signed int
+	uint innerXoff_hi;
+
+	uint windowHeight;
+	uint windowWidth;
+	uint memDepth;
+	float alpha;
+	float xoff;
+	float xscale;
+	float ybase;
+	float yscale;
+	float yoff;
+};
+
+//Indexes so we know which samples go to which X pixel range
+layout(std430, binding=3) buffer index
+{
+	uint xind[];
+};
+
+//Maximum height of a single waveform, in pixels.
+//This is enough for a nearly fullscreen 4K window so should be plenty.
+#define MAX_HEIGHT		2048
+
+//Number of columns of pixels per thread block
+#define COLS_PER_BLOCK	2
+
+layout(local_size_x=COLS_PER_BLOCK, local_size_y=1, local_size_z=1) in;
+
+//Interpolate a Y coordinate
+float InterpolateY(vec2 left, vec2 right, float slope, float x)
+{
+	return left.y + ( (x - left.x) * slope );
+}
+
+//All this just because most Intel integrated GPUs lack GL_ARB_gpu_shader_int64...
+float FetchX(uint i)
+{
+	//Fetch the input
+	uint xpos_lo = xpos[i*2];
+	uint xpos_hi = xpos[i*2 + 1];
+	uint offset_lo = innerXoff_lo;
+
+	//Chop off the MSB from the low halves and sum them separately
+	//(these might turn into carries)
+	uint msb_pos = (xpos_lo >> 31);
+	uint msb_off = (offset_lo >> 31);
+	xpos_lo &= 0x7fffffff;
+	offset_lo &= 0x7fffffff;
+	uint msb_sum = msb_pos + msb_off;
+
+	//Sum the low halves without MSBs (cannot generate a carry)
+	uint sum_lo = xpos_lo + offset_lo;
+
+	//Sum the high halves (no need to worry about carries)
+	uint sum_hi = xpos_hi + innerXoff_hi;
+
+	//Patch up the carries between halves
+	msb_sum += (sum_lo >> 31);
+	sum_lo &= 0x7fffffff;
+	sum_lo |= (msb_sum & 1) << 31;
+	sum_hi += (msb_sum >> 1);
+
+	//If MSB is 1, we're negative.
+	//Calculate the twos complement by flipping all the bits.
+	//To complete the complement we need to add 1, but that comes later.
+	bool negative = ( (sum_hi & 0x80000000) == 0x80000000 );
+	if(negative)
+	{
+		sum_lo = ~sum_lo;
+		sum_hi = ~sum_hi;
+	}
+
+	//Convert back to floating point
+	float f = (float(sum_hi) * 4294967296.0) + float(sum_lo);
+	if(negative)
+		f += 1;
+	return f;
+}
+
+//Shared buffer for the local working buffer
+shared float g_workingBuffer[COLS_PER_BLOCK][MAX_HEIGHT];
+
+void main()
+{
+	//Abort if window height is too big, or if we're off the end of the window
+	if(windowHeight > MAX_HEIGHT)
+		return;
+	if(gl_GlobalInvocationID.x > windowWidth)
+		return;
+	if(memDepth < 2)
+		return;
+
+	//Clear column to blank in the first thread of the block
+	if(gl_LocalInvocationID.y == 0)
+	{
+		for(uint y=0; y<windowHeight; y++)
+			g_workingBuffer[gl_LocalInvocationID.x][y] = 0;
+	}
+	barrier();
+	memoryBarrierShared();
+
+	//Loop over the waveform, starting at the leftmost point that overlaps this column
+	uint istart = xind[gl_GlobalInvocationID.x];
+	vec2 left = vec2(FetchX(istart)*xscale + xoff, (voltage[istart] + yoff)*yscale + ybase);
+	vec2 right;
+	for(uint i=istart; i<(memDepth-2); i++)
+	{
+		//Fetch coordinates of the current and upcoming sample
+		right = vec2(FetchX(i+1)*xscale + xoff, (voltage[i+1] + yoff)*yscale + ybase);
+
+		//If the current point is right of us, stop
+		if(left.x > gl_GlobalInvocationID.x + 1)
+			break;
+
+		//If the upcoming point is still left of us, we're not there yet
+		if(right.x < gl_GlobalInvocationID.x)
+		{
+			left = right;
+			continue;
+		}
+
+		//To start, assume we're drawing the entire segment
+		float starty = left.y;
+		float endy = right.y;
+
+		//Interpolate analog signals if either end is outside our column
+		float slope = (right.y - left.y) / (right.x - left.x);
+		if(left.x < gl_GlobalInvocationID.x)
+			starty = InterpolateY(left, right, slope, gl_GlobalInvocationID.x);
+		if(right.x > gl_GlobalInvocationID.x + 1)
+			endy = InterpolateY(left, right, slope, gl_GlobalInvocationID.x + 1);
+
+		//Clip to window size
+		starty = min(starty, MAX_HEIGHT);
+		endy = min(endy, MAX_HEIGHT);
+
+		//Sort Y coordinates from min to max
+		int ymin = int(min(starty, endy));
+		int ymax = int(max(starty, endy));
+
+		//Push current point down the pipeline
+		left = right;
+
+		//Fill in the space between min and max for this segment
+		for(int y=ymin; y <= ymax; y++)
+			g_workingBuffer[gl_LocalInvocationID.x][y] += alpha;
+
+		//TODO: antialiasing
+		//TODO: decimation at very wide zooms
+	}
+
+	//Copy working buffer to RGB output
+	for(uint y=0; y<windowHeight; y++)
+		imageStore(outputTex, ivec2(gl_GlobalInvocationID.x, y), vec4(0, 0, 0, g_workingBuffer[gl_LocalInvocationID.x][y]));
+}
+1 −0		CMakeLists.txt
+6 −1		glscopeclient-manual.tex
+ −		images/filters/64b66b.png
+ −		images/filters/8b10b.png
+ −		images/filters/ac-couple.png
+ −		images/filters/autocorrelation.png
+ −		images/filters/tmds.png
+ −		images/graph-editor.png
+166 −17		section-decodes.tex
+4 −3		section-gettingstarted.tex
+28 −0		section-grapheditor.tex
+1 −3		section-legal.tex
+2 −2		section-protoanalyzer.tex
+1 −1		scopeprotocols/AutocorrelationFilter.cpp
+2 −0		scopeprotocols/CMakeLists.txt
+154 −0		scopeprotocols/DCDMeasurement.cpp
+61 −0		scopeprotocols/DCDMeasurement.h
+7 −2		scopeprotocols/DDJMeasurement.cpp
+155 −0		scopeprotocols/ISIMeasurement.cpp
+61 −0		scopeprotocols/ISIMeasurement.h
+1 −1		scopeprotocols/JitterSpectrumFilter.cpp
+2 −0		scopeprotocols/PkPkMeasurement.cpp
+2 −0		scopeprotocols/scopeprotocols.cpp
+2 −0		scopeprotocols/scopeprotocols.h