From dd795a5a44996c5016c47d7c764c836c4a8d94e5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Joachim=20Stro=CC=88mbergson?= <joachim@secworks.se>
Date: Wed, 10 Jun 2015 09:19:40 +0200
Subject: Added cycle counter to the montprod testbench to measure the
 execution time.

---
 src/tb/tb_montprod.v | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/src/tb/tb_montprod.v b/src/tb/tb_montprod.v
index 601e7f8..f4d04c7 100644
--- a/src/tb/tb_montprod.v
+++ b/src/tb/tb_montprod.v
@@ -57,10 +57,15 @@ module tb_montprod();
   parameter CLK_HALF_PERIOD = 2;
   parameter CLK_PERIOD = 2 * CLK_HALF_PERIOD;
 
+  parameter DISPLAY_TEST_CYCLES = 1;
+
 
 //----------------------------------------------------------------
 // Register and Wire declarations.
 //----------------------------------------------------------------
+  reg [31 : 0]  test_cycle_ctr;
+  reg           test_cycle_ctr_rst;
+  reg           test_cycle_ctr_inc;
 
 reg           tb_clk;
 reg           tb_reset_n;
@@ -139,6 +144,55 @@ always
   end // clk_gen
 
 
+  //----------------------------------------------------------------
+  // test_cycle_counter
+  //
+  // Used to measure the number of cycles it takes to perform
+  // a given test case.
+  //----------------------------------------------------------------
+  always @ (posedge tb_clk)
+    begin
+      if (test_cycle_ctr_rst)
+        test_cycle_ctr = 64'h0000000000000000;
+
+      if (test_cycle_ctr_inc)
+        test_cycle_ctr = test_cycle_ctr + 1;
+    end
+
+
+  //----------------------------------------------------------------
+  // start_test_cycle_ctr
+  //
+  // Reset and start the test cycle counter.
+  //----------------------------------------------------------------
+  task start_test_cycle_ctr();
+    begin
+      test_cycle_ctr_rst = 1;
+      #(CLK_PERIOD);
+      test_cycle_ctr_rst = 0;
+
+      test_cycle_ctr_inc = 1;
+    end
+  endtask // start_test_cycle_ctr()
+
+
+  //----------------------------------------------------------------
+  // stop_test_cycle_ctr()
+  //
+  // Stop the test cycle counter and optionally display the
+  // result.
+  //----------------------------------------------------------------
+  task stop_test_cycle_ctr();
+    begin
+      test_cycle_ctr_inc = 0;
+      #(CLK_PERIOD);
+
+      if (DISPLAY_TEST_CYCLES)
+        $display("*** Number of cycles performed during test: 0x%016x", test_cycle_ctr);
+    end
+  endtask // stop_test_cycle_ctr()
+
+
 //----------------------------------------------------------------
 // S monitor
 //----------------------------------------------------------------
@@ -314,8 +368,14 @@ task test_mont_prod(
     $display("*** Test vector copied");
     wait_ready();
     tb_length = length;
+
+    start_test_cycle_ctr();
+
     signal_calculate();
     wait_ready();
+
+    stop_test_cycle_ctr();
+
     begin: verify_test_vectors
       integer i;
       integer j;
-- 
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