From 1b987d12d7cc7fa220434f7ca093b23091066e50 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Joachim=20Stro=CC=88mbergson?= <joachim@secworks.se>
Date: Fri, 29 Jun 2018 13:53:08 +0200
Subject: Adding dut to top level testbench. Adding API definitions. Adding
 tasks to read and write words from and to the dut API.

---
 src/tb/tb_keywrap.v | 140 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 135 insertions(+), 5 deletions(-)

diff --git a/src/tb/tb_keywrap.v b/src/tb/tb_keywrap.v
index f42d58f..29249ed 100644
--- a/src/tb/tb_keywrap.v
+++ b/src/tb/tb_keywrap.v
@@ -39,12 +39,73 @@
 
 module tb_keywrap();
 
+  parameter DEBUG     = 0;
+
   parameter CLK_HALF_PERIOD = 1;
   parameter CLK_PERIOD      = 2 * CLK_HALF_PERIOD;
 
-  integer cycle_ctr;
-  reg tb_sys_clk;
-  reg tb_reset_n;
+  // API for the core.
+  localparam ADDR_NAME0       = 8'h00;
+  localparam ADDR_NAME1       = 8'h01;
+  localparam ADDR_VERSION     = 8'h02;
+
+  localparam ADDR_CTRL        = 8'h08;
+  localparam CTRL_INIT_BIT    = 0;
+  localparam CTRL_NEXT_BIT    = 1;
+
+  localparam ADDR_STATUS      = 8'h09;
+  localparam STATUS_READY_BIT = 0;
+  localparam STATUS_VALID_BIT = 1;
+
+  localparam ADDR_CONFIG      = 8'h0a;
+  localparam CTRL_ENCDEC_BIT  = 0;
+  localparam CTRL_KEYLEN_BIT  = 1;
+
+  localparam ADDR_RLEN        = 8'h0c;
+  localparam ADDR_A_LSB       = 8'h0e;
+  localparam ADDR_A_MSB       = 8'h0f;
+
+  localparam ADDR_KEY0        = 8'h10;
+  localparam ADDR_KEY7        = 8'h17;
+
+  localparam ADDR_WRITE_DATA  = 8'h20;
+
+  localparam ADDR_READ_DATA   = 8'h30;
+
+
+  //----------------------------------------------------------------
+  // Register and Wire declarations.
+  //----------------------------------------------------------------
+  reg [31 : 0]  cycle_ctr;
+  reg [31 : 0]  error_ctr;
+  reg [31 : 0]  tc_ctr;
+
+  reg [31 : 0]  read_data;
+  reg [127 : 0] result_data;
+
+  reg           tb_clk;
+  reg           tb_reset_n;
+  reg           tb_cs;
+  reg           tb_we;
+  reg [7  : 0]  tb_address;
+  reg [31 : 0]  tb_write_data;
+  wire [31 : 0] tb_read_data;
+  wire          tb_error;
+
+
+  //----------------------------------------------------------------
+  // Device Under Test.
+  //----------------------------------------------------------------
+  keywrap dut(
+              .clk(tb_clk),
+              .reset_n(tb_reset_n),
+              .cs(tb_cs),
+              .we(tb_we),
+              .address(tb_address),
+              .write_data(tb_write_data),
+              .read_data(tb_read_data),
+              .error(tb_error)
+             );
 
 
   //----------------------------------------------------------------
@@ -55,7 +116,7 @@ module tb_keywrap();
   always
     begin : clk_gen
       #CLK_HALF_PERIOD;
-      tb_sys_clk = !tb_sys_clk;
+      tb_clk = !tb_clk;
     end // clk_gen
 
 
@@ -73,6 +134,75 @@ module tb_keywrap();
     end
 
 
+  //----------------------------------------------------------------
+  // 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
+    end
+  endtask // read_word
+
+
+  //----------------------------------------------------------------
+  // write_word()
+  //
+  // Write the given word to the DUT using the DUT interface.
+  //----------------------------------------------------------------
+  task write_word(input [11 : 0] address,
+                  input [31 : 0] word);
+    begin
+      if (DEBUG)
+        begin
+          $display("*** Writing 0x%08x to 0x%02x.", word, address);
+          $display("");
+        end
+
+      tb_address = address;
+      tb_write_data = word;
+      tb_cs = 1;
+      tb_we = 1;
+      #(2 * CLK_PERIOD);
+      tb_cs = 0;
+      tb_we = 0;
+    end
+  endtask // write_word
+
+
+  //----------------------------------------------------------------
+  // wait_ready
+  //
+  // Wait for the DUT to signal that the result is ready
+  //----------------------------------------------------------------
+  task wait_ready;
+    begin : wait_ready
+      reg rdy;
+      rdy = 1'b0;
+
+      while (rdy != 1'b1)
+        begin
+          read_word(ADDR_STATUS);
+          rdy = tb_read_data[STATUS_READY_BIT];
+        end
+    end
+  endtask // wait_ready
+
+
   //----------------------------------------------------------------
   // init_sim()
   //
@@ -82,7 +212,7 @@ module tb_keywrap();
   initial
     begin
       cycle_ctr     = 0;
-      tb_sys_clk    = 0;
+      tb_clk        = 0;
       tb_reset_n    = 0;
 
       #(CLK_PERIOD * 10);
-- 
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