From dd11b056b46be8f5ee17147265c4ba7dd6b660f2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Joachim=20Stro=CC=88mbergson?= <joachim@secworks.se>
Date: Thu, 2 Apr 2015 15:06:43 +0200
Subject: Fixed syntax and added init functionality for testing the dut.

---
 src/tb/tb_csprng_fifo.v | 105 ++++++++++++++----------------------------------
 1 file changed, 30 insertions(+), 75 deletions(-)

diff --git a/src/tb/tb_csprng_fifo.v b/src/tb/tb_csprng_fifo.v
index c0b45ec..c5e283e 100644
--- a/src/tb/tb_csprng_fifo.v
+++ b/src/tb/tb_csprng_fifo.v
@@ -81,41 +81,24 @@ module tb_csprng_fifo();
   wire [31 : 0] tb_rnd_data;
   reg           tb_rnd_ack;
 
-  reg           tb_discard;
-  reg           tb_test_mode;
-
-  wire          tb_ready;
-  wire          tb_more_seed;
-  wire          tb_security_error;
-  reg           tb_seed_syn;
-  reg [511 : 0] tb_seed_data;
-  wire          tb_seed_ack;
-  wire [31: 0]  tb_rnd_data;
-  wire          tb_rnd_syn;
-  reg           tb_rnd_ack;
-
-  wire [7 : 0]  tb_debug;
-  reg           tb_debug_update;
-
-  reg [31 : 0]  read_data;
-
+  integer i;
 
   //----------------------------------------------------------------
   // Device Under Test.
   //----------------------------------------------------------------
-  trng_csprng dut(
-                  .clk(tb_clk),
-                  .reset_n(tb_reset_n),
+  trng_csprng_fifo dut(
+                       .clk(tb_clk),
+                       .reset_n(tb_reset_n),
 
-                  .csprng_data(tb_csprng_data),
-                  .csprng_data_valid(tb_csprng_data_valid),
-                  .discard(tb_discard),
-                  .more_data(tb_more_data),
+                       .csprng_data(tb_csprng_data),
+                       .csprng_data_valid(tb_csprng_data_valid),
+                       .discard(tb_discard),
+                       .more_data(tb_more_data),
 
-                  .rnd_syn(tb_rnd_syn),
-                  .rnd_data(tb_rnd_data),
-                  .rnd_ack(tb_rnd_ack)
-                  );
+                       .rnd_syn(tb_rnd_syn),
+                       .rnd_data(tb_rnd_data),
+                       .rnd_ack(tb_rnd_ack)
+                      );
 
 
   //----------------------------------------------------------------
@@ -159,59 +142,28 @@ module tb_csprng_fifo();
       $display("cycle: 0x%016x", cycle_ctr);
       $display("State of DUT");
       $display("------------");
+      $display("rnd_syn = 0x%01x, rnd_ack = 0x%01x, rnd_data = 0x%08x",
+               tb_rnd_syn, tb_rnd_ack, tb_rnd_data);
       $display("");
     end
   endtask // dump_dut_state
 
 
   //----------------------------------------------------------------
-  // write_word()
+  // gen_csprng_data
   //
-  // Write the given word to the DUT using the DUT interface.
+  // Generate test data with distinct patterns as requested
+  // by the dut.
   //----------------------------------------------------------------
-  task write_word(input [11 : 0]  address,
-                  input [31 : 0] word);
+  always @ (posedge tb_more_data)
     begin
-      if (DEBUG)
-        begin
-          $display("*** Writing 0x%08x to 0x%02x.", word, address);
-          $display("");
-        end
+      for (i = 0 ; i < 16 ; i = i + 1)
+        tb_csprng_data[i * 32 +: 32] = ~tb_csprng_data[i * 32 +: 32] + 32'h01010101;
 
-      tb_address = address;
-      tb_write_data = word;
-      tb_cs = 1;
-      tb_we = 1;
+      tb_csprng_data_valid = 1'b1;
       #(2 * CLK_PERIOD);
-      tb_cs = 0;
-      tb_we = 0;
-    end
-  endtask // write_word
-
-
-  //----------------------------------------------------------------
-  // read_word()
-  //
-  // Read a data word from the given address in the DUT.
-  // the word read will be available in the global variable
-  // read_data.
-  //----------------------------------------------------------------
-  task read_word(input [11 : 0]  address);
-    begin
-      tb_address = address;
-      tb_cs = 1;
-      tb_we = 0;
-      #(CLK_PERIOD);
-      read_data = tb_read_data;
-      tb_cs = 0;
-
-      if (DEBUG)
-        begin
-          $display("*** Reading 0x%08x from 0x%02x.", read_data, address);
-          $display("");
-        end
+      tb_csprng_data_valid = 1'b0;
     end
-  endtask // read_word
 
 
   //----------------------------------------------------------------
@@ -258,6 +210,8 @@ module tb_csprng_fifo();
   // as setting the DUT inputs to defined values.
   //----------------------------------------------------------------
   task init_sim();
+    integer i;
+
     begin
       cycle_ctr       = 0;
       error_ctr       = 0;
@@ -272,12 +226,11 @@ module tb_csprng_fifo();
       tb_write_data   = 32'h00000000;
 
       tb_discard      = 0;
-      tb_test_mode    = 0;
+      tb_rnd_ack      = 1;
+
+      for (i = 0 ; i < 16 ; i = i + 1)
+        tb_csprng_data[i * 32 +: 32] = 32'h01010101 << (i + 1);
 
-      tb_seed_syn     = 0;
-      tb_seed_data    = {16{32'h00000000}};
-      tb_rnd_ack      = 0;
-      tb_debug_update = 0;
     end
   endtask // init_sim
 
@@ -299,6 +252,8 @@ module tb_csprng_fifo();
       reset_dut();
       dump_dut_state();
 
+      #(100000 * CLK_PERIOD)
+
       display_test_results();
 
       $display("");
-- 
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