From da9d4eed5e4e4cc80d1e2f524887a706c592f768 Mon Sep 17 00:00:00 2001
From: Jim Knowler <jim.knowler2@gmail.com>
Date: Mon, 3 Jan 2022 14:31:34 +0000
Subject: [PATCH] Trace: truncate large traces when rendering them (including
 diffs for MatchTrace)

---
 gtestverilog/example/Counter.test.cpp | 12 +++++++++++
 gtestverilog/lib/MatchesTrace.cpp     | 30 +++++++++++++++++++++++----
 gtestverilog/lib/Trace.cpp            | 16 ++++++++++++--
 3 files changed, 52 insertions(+), 6 deletions(-)

diff --git a/gtestverilog/example/Counter.test.cpp b/gtestverilog/example/Counter.test.cpp
index 84fcf26..35e3f27 100644
--- a/gtestverilog/example/Counter.test.cpp
+++ b/gtestverilog/example/Counter.test.cpp
@@ -75,5 +75,17 @@ TEST_F(Counter, ShouldSimulate) {
         .port(i_simulate_combinatorial).signal( "01" ).repeat(11)
         .port(i_simulate_sequential).signal( "10" ).repeat(11);
 
+    ASSERT_THAT(testBench.trace, MatchesTrace(traceExpected));
+}
+
+TEST_F(Counter, ShouldHandleLargeTraces) {
+    testBench.reset();
+    testBench.tick(1000);
+
+    const Trace traceExpected = TraceBuilder()
+        .port(i_clk).signal( "10" ).repeat(1001)
+        .port(i_simulate_combinatorial).signal( "01" ).repeat(1001)
+        .port(i_simulate_sequential).signal( "10" ).repeat(1001);
+
     ASSERT_THAT(testBench.trace, MatchesTrace(traceExpected));
 }
\ No newline at end of file
diff --git a/gtestverilog/lib/MatchesTrace.cpp b/gtestverilog/lib/MatchesTrace.cpp
index 59a082c..b431a02 100644
--- a/gtestverilog/lib/MatchesTrace.cpp
+++ b/gtestverilog/lib/MatchesTrace.cpp
@@ -1,7 +1,10 @@
 #include "MatchesTrace.h"
 
+#include <algorithm>
+
 namespace gtestverilog {
 namespace matches_trace {
+    const size_t kMaxTraceRenderSize = 80;
 
     bool compare(const Trace& actual, const Trace& expected, ::testing::MatchResultListener& listener) {
         bool hasMatched = true;
@@ -43,18 +46,37 @@ namespace matches_trace {
                                 << ConsoleColour().reset()
                                 << "\n";
 
+                        std::vector<Step> stepsExpectedRender;
+                        std::vector<Step> stepsActualRender;
+
+                        size_t stepStart = 0;
+                        size_t stepEnd = sizeActual;
+
+                        if (sizeActual > kMaxTraceRenderSize) {
+                            stepStart = (step > (kMaxTraceRenderSize/2)) ? step - (kMaxTraceRenderSize/2) : 0;
+                            stepEnd = std::min(stepEnd, stepStart + kMaxTraceRenderSize);
+
+                            listener << "Note: Diff truncated to steps " << stepStart << " to " << stepEnd << "\n";
+
+                            stepsExpectedRender = std::vector<Step>(stepsExpected.begin() + stepStart, stepsExpected.begin() + stepEnd);
+                            stepsActualRender = std::vector<Step>(stepsActual.begin() + stepStart, stepsActual.begin() + stepEnd);
+                        } else {
+                            stepsExpectedRender = stepsExpected;
+                            stepsActualRender = stepsActual;
+                        }
+
                         size_t maxPortLabelSize = expected.getMaxPortLabelSize();
 
                         listener << "\n";
                         listener << "Expected:";
-                        Trace::renderPortDiff(*(listener.stream()), 'v', ConsoleColour::kGreen, maxPortLabelSize-9, portDesc, stepsExpected, stepsActual);
+                        Trace::renderPortDiff(*(listener.stream()), 'v', ConsoleColour::kGreen, maxPortLabelSize-9, portDesc, stepsExpectedRender, stepsActualRender);
 
-                        Trace::renderPort(*(listener.stream()), maxPortLabelSize, portDesc, stepsExpected);
+                        Trace::renderPort(*(listener.stream()), maxPortLabelSize, portDesc, stepsExpectedRender);
 
                         listener << "  Actual:";
-                        Trace::renderPortDiff(*(listener.stream()), 'v', ConsoleColour::kRed, maxPortLabelSize-9, portDesc, stepsExpected, stepsActual);
+                        Trace::renderPortDiff(*(listener.stream()), 'v', ConsoleColour::kRed, maxPortLabelSize-9, portDesc, stepsExpectedRender, stepsActualRender);
 
-                        Trace::renderPort(*(listener.stream()), maxPortLabelSize, portDesc, stepsActual);
+                        Trace::renderPort(*(listener.stream()), maxPortLabelSize, portDesc, stepsActualRender);
                     }
 
                     hasMatched = false;
diff --git a/gtestverilog/lib/Trace.cpp b/gtestverilog/lib/Trace.cpp
index afd34c6..a3e9c26 100644
--- a/gtestverilog/lib/Trace.cpp
+++ b/gtestverilog/lib/Trace.cpp
@@ -2,8 +2,11 @@
 
 #include <cstring>
 #include <cmath>
+#include <iostream>
 
 namespace gtestverilog {
+    const size_t kMaxTraceRenderSize = 80;
+
     Trace::Trace() {
     }
 
@@ -137,10 +140,19 @@ namespace gtestverilog {
         os << ConsoleColour().reset();
 
         auto& steps = trace.getSteps();
+
+        std::vector<Step> stepsRender;
+
+        if (steps.size() <= kMaxTraceRenderSize) {
+            stepsRender = steps;
+        } else {
+            stepsRender = std::vector<Step>(steps.begin(), steps.begin() + kMaxTraceRenderSize);
+            os << "Note: Trace truncated to first " << kMaxTraceRenderSize << " steps\n";
+        }
         
         size_t maxPortLabelSize = trace.getMaxPortLabelSize();
 
-        renderTimeline(os, maxPortLabelSize + 11, steps.size());
+        renderTimeline(os, maxPortLabelSize + 11, stepsRender.size());
 
         for (uint32_t portId=0; portId<64; portId++) {
             if (!trace.hasPort(portId)) {
@@ -149,7 +161,7 @@ namespace gtestverilog {
 
             const PortDescription& portDesc = trace.getPortDescription(portId);
 
-            Trace::renderPort(os, maxPortLabelSize, portDesc, steps);
+            Trace::renderPort(os, maxPortLabelSize, portDesc, stepsRender);
         }
 
         return os;