From dfd22b2b0733502fd01d67de81ea8472b453360a Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Sun, 5 Nov 2017 06:51:29 -0500
Subject: [PATCH] Examples: Add +trace flag at runtime

---
 examples/tracing_c/Makefile     |  2 +-
 examples/tracing_c/sim_main.cpp | 19 ++++++++++++-------
 examples/tracing_sc/Makefile    |  2 +-
 examples/tracing_sc/sc_main.cpp | 17 +++++++++++------
 4 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/examples/tracing_c/Makefile b/examples/tracing_c/Makefile
index 7383b7c42..70bb03dbd 100644
--- a/examples/tracing_c/Makefile
+++ b/examples/tracing_c/Makefile
@@ -73,7 +73,7 @@ run:
 	@echo
 	@echo "-- RUN ---------------------"
 	@mkdir -p logs
-	obj_dir/Vtop | tee logs/sim.log
+	obj_dir/Vtop +trace | tee logs/sim.log
 
 	@echo
 	@echo "-- COVERAGE ----------------"
diff --git a/examples/tracing_c/sim_main.cpp b/examples/tracing_c/sim_main.cpp
index 44dd601ea..76d126688 100644
--- a/examples/tracing_c/sim_main.cpp
+++ b/examples/tracing_c/sim_main.cpp
@@ -41,14 +41,19 @@ int main(int argc, char** argv, char** env) {
     // Construct the Verilated model, from Vtop.h generated from Verilating "top.v"
     Vtop* top = new Vtop; // Or use a const unique_ptr, or the VL_UNIQUE_PTR wrapper
 
-    // If verilator was invoked with --trace, open trace
 #if VM_TRACE
-    Verilated::traceEverOn(true);  // Verilator must compute traced signals
-    VL_PRINTF("Enabling waves into logs/vlt_dump.vcd...\n");
-    VerilatedVcdC* tfp = new VerilatedVcdC;
-    top->trace(tfp, 99);  // Trace 99 levels of hierarchy
-    mkdir("logs", 0777);
-    tfp->open("logs/vlt_dump.vcd");  // Open the dump file
+    // If verilator was invoked with --trace argument,
+    // and if at run time passed the +trace argument, turn on tracing
+    VerilatedVcdC* tfp = NULL;
+    const char* flag = Verilated::commandArgsPlusMatch("trace");
+    if (flag && 0==strcmp(flag, "+trace")) {
+        Verilated::traceEverOn(true);  // Verilator must compute traced signals
+        VL_PRINTF("Enabling waves into logs/vlt_dump.vcd...\n");
+        tfp = new VerilatedVcdC;
+        top->trace(tfp, 99);  // Trace 99 levels of hierarchy
+        mkdir("logs", 0777);
+        tfp->open("logs/vlt_dump.vcd");  // Open the dump file
+    }
 #endif
 
     // Set some inputs
diff --git a/examples/tracing_sc/Makefile b/examples/tracing_sc/Makefile
index df56150c3..6a24a4ebc 100644
--- a/examples/tracing_sc/Makefile
+++ b/examples/tracing_sc/Makefile
@@ -81,7 +81,7 @@ run:
 	@echo
 	@echo "-- RUN ---------------------"
 	@mkdir -p logs
-	obj_dir/Vtop | tee logs/sim.log
+	obj_dir/Vtop +trace | tee logs/sim.log
 
 	@echo
 	@echo "-- COVERAGE ----------------"
diff --git a/examples/tracing_sc/sc_main.cpp b/examples/tracing_sc/sc_main.cpp
index 29ed072cb..2365f0f60 100644
--- a/examples/tracing_sc/sc_main.cpp
+++ b/examples/tracing_sc/sc_main.cpp
@@ -87,13 +87,18 @@ int sc_main(int argc, char* argv[]) {
     sc_start(1);
 #endif
 
-    // Turn on waves
 #if VM_TRACE
-    cout << "Enabling waves into logs/vlt_dump.vcd...\n";
-    VerilatedVcdSc* tfp = new VerilatedVcdSc;
-    top->trace (tfp, 99);
-    mkdir("logs", 0777);
-    tfp->open ("logs/vlt_dump.vcd");
+    // If verilator was invoked with --trace argument,
+    // and if at run time passed the +trace argument, turn on tracing
+    VerilatedVcdSc* tfp = NULL;
+    const char* flag = Verilated::commandArgsPlusMatch("trace");
+    if (flag && 0==strcmp(flag, "+trace")) {
+        cout << "Enabling waves into logs/vlt_dump.vcd...\n";
+        VerilatedVcdSc* tfp = new VerilatedVcdSc;
+        top->trace (tfp, 99);
+        mkdir("logs", 0777);
+        tfp->open ("logs/vlt_dump.vcd");
+    }
 #endif
 
     // Simulate until $finish