Add plusargs support to testbench.cc

Signed-off-by: Claire Wolf <claire@symbioticeda.com>

testbench.cc

@@ -7,23 +7,37 @@ int main(int argc, char **argv, char **env)
 	printf("Recommended: Verilator 4.0 or later.\n");
 
 	Verilated::commandArgs(argc, argv);
-	Verilated::traceEverOn(true);
 	Vpicorv32_wrapper* top = new Vpicorv32_wrapper;
 
-	VerilatedVcdC* tfp = new VerilatedVcdC;
-	top->trace (tfp, 99);
-        tfp->open ("testbench.vcd");
+	// Tracing (vcd)
+	VerilatedVcdC* tfp = NULL;
+	const char* flag_vcd = Verilated::commandArgsPlusMatch("vcd");
+	if (flag_vcd && 0==strcmp(flag_vcd, "+vcd")) {
+		Verilated::traceEverOn(true);
+		tfp = new VerilatedVcdC;
+		top->trace (tfp, 99);
+		tfp->open("testbench.vcd");
+	}
+
+	// Tracing (data bus, see showtrace.py)
+	FILE *trace_fd = NULL;
+	const char* flag_trace = Verilated::commandArgsPlusMatch("trace");
+	if (flag_trace && 0==strcmp(flag_trace, "+trace")) {
+		trace_fd = fopen("testbench.trace", "w");
+	}
+
 	top->clk = 0;
 	int t = 0;
 	while (!Verilated::gotFinish()) {
 		if (t > 200)
 			top->resetn = 1;
 		top->clk = !top->clk;
 		top->eval();
-		tfp->dump (t);
+		if (tfp) tfp->dump (t);
+		if (trace_fd && top->clk && top->trace_valid) fprintf(trace_fd, "%9.9lx\n", top->trace_data);
 		t += 5;
 	}
-	tfp->close();
+	if (tfp) tfp->close();
 	delete top;
 	exit(0);
 }