From 9a299546709298dd2788dc16c914eb0b8ec1a205 Mon Sep 17 00:00:00 2001
From: Torsten Meissner <torsten@meissneronline.net>
Date: Sun, 25 Mar 2012 03:59:47 +0200
Subject: [PATCH] new stimuli, checker & reset processes

---
 des/sim/verilog/tb_des.v | 67 ++++++++++++++++++++++++++++++----------
 1 file changed, 51 insertions(+), 16 deletions(-)

diff --git a/des/sim/verilog/tb_des.v b/des/sim/verilog/tb_des.v
index a9201e7..6c8870a 100644
--- a/des/sim/verilog/tb_des.v
+++ b/des/sim/verilog/tb_des.v
@@ -27,39 +27,74 @@ module tb_des;
      $dumpvars (0, tb_des);
   end
 
+  reg reset;
+  reg clk = 0;
+  reg mode;
+  reg [0:63] key;
+  reg [0:63] datain;
+  reg validin;
+  integer index;
+  integer outdex;
+  wire [0:63] dataout;
+  wire validout;
+
+  reg [0:63] variable_plaintext_known_answers [0:63];
 
-  reg reset = 0;
+  initial begin
+    $readmemh("stimuli.txt", variable_plaintext_known_answers);
+  end
 
   initial begin
+    reset = 1;
+    #1  reset = 0;
     #20 reset = 1;
     #1000 $finish;
   end
 
-  reg clk = 0;
   always #5 clk = !clk;
 
-  reg mode;
-  reg [0:63] key;
-  reg [0:63] datain;
-  reg validin;
-
-  always @(posedge clk, reset) begin
-    if(~reset) begin
+  initial
+    forever @(negedge reset) begin
+      disable stimuli;
+      disable checker;
       mode    <= 0;
       validin <= 0;
       key     <= 0;
       datain  <= 0;
     end
-    else begin
-      mode    <= 1;
+
+  always begin : stimuli
+    wait (reset)
+    @(posedge clk)
+      // Variable plaintext known answer test
+      datain <= 64'h8000000000000000;
+      mode    <= 0;
       validin <= 1;
-      key     <= key + 1;
-      datain  <= datain + 1;
-    end
+      key     <= 64'h0101010101010101;
+      for(index = 0; index < 64; index = index + 1)
+      begin
+        @(posedge clk)
+          datain  <= {1'b0, datain[0:62]};
+      end
+      validin <= 0;
   end
 
-  wire [0:63] dataout;
-  wire validout;
+  always begin : checker
+    wait (reset)
+    // Variable plaintext known answer test
+    wait (validout)
+    for(outdex = 0; outdex < 64; outdex = outdex + 1)
+    begin
+      @(posedge clk)
+      if (dataout == variable_plaintext_known_answers[outdex]) begin
+        $display ("okay");
+      end else begin
+        $display ("error, output was %h - should have been %h", dataout, variable_plaintext_known_answers[outdex]);
+      end
+    end
+    @(posedge clk)
+      $finish;
+  end
 
   des i_des (
     .reset_i(reset),