From 668d5253a59f3b106bae6d1fca8ba1873b2fdce0 Mon Sep 17 00:00:00 2001
From: "N. Engelhardt" <nak@symbioticeda.com>
Date: Fri, 16 Oct 2020 18:19:58 +0200
Subject: [PATCH] sim -vcd: add date, version, and option for timescale

---
 passes/sat/sim.cc | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/passes/sat/sim.cc b/passes/sat/sim.cc
index fb496ff87..4c9af0bf6 100644
--- a/passes/sat/sim.cc
+++ b/passes/sat/sim.cc
@@ -633,6 +633,7 @@ struct SimWorker : SimShared
 	SimInstance *top = nullptr;
 	std::ofstream vcdfile;
 	pool<IdString> clock, clockn, reset, resetn;
+	std::string timescale;
 
 	~SimWorker()
 	{
@@ -644,6 +645,15 @@ struct SimWorker : SimShared
 		if (!vcdfile.is_open())
 			return;
 
+		vcdfile << stringf("$version %s $end\n", yosys_version_str);
+		vcdfile << stringf("$date ");
+		std::time_t t = std::time(nullptr);
+		vcdfile << std::put_time(std::localtime(&t), "%c %Z");
+		vcdfile << stringf(" $end\n");
+
+		if (!timescale.empty())
+			vcdfile << stringf("$timescale %s $end\n", timescale.c_str());
+
 		int id = 1;
 		top->write_vcd_header(vcdfile, id);
 
@@ -783,6 +793,9 @@ struct SimPass : public Pass {
 		log("    -zinit\n");
 		log("        zero-initialize all uninitialized regs and memories\n");
 		log("\n");
+		log("    -timescale <string>\n");
+		log("        include the specified timescale declaration in the vcd\n");
+		log("\n");
 		log("    -n <integer>\n");
 		log("        number of cycles to simulate (default: 20)\n");
 		log("\n");
@@ -833,6 +846,10 @@ struct SimPass : public Pass {
 				worker.resetn.insert(RTLIL::escape_id(args[++argidx]));
 				continue;
 			}
+			if (args[argidx] == "-timescale" && argidx+1 < args.size()) {
+				worker.timescale = args[++argidx];
+				continue;
+			}
 			if (args[argidx] == "-a") {
 				worker.hide_internal = false;
 				continue;