From 71ca3266826c281089f44fffaa561c7f28760aee Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Joachim=20Stro=CC=88mbergson?= <joachim@secworks.se>
Date: Thu, 27 Aug 2015 13:10:23 +0200
Subject: Added process to generate need seeds with differentg patterns and
 communicate with the DUT using the seed update protocol. Minor nits.

---
 src/tb/tb_csprng.v | 60 +++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 53 insertions(+), 7 deletions(-)

diff --git a/src/tb/tb_csprng.v b/src/tb/tb_csprng.v
index 5cfb398..4e2efec 100644
--- a/src/tb/tb_csprng.v
+++ b/src/tb/tb_csprng.v
@@ -50,7 +50,7 @@ module tb_csprng();
   //----------------------------------------------------------------
   // Internal constant and parameter definitions.
   //----------------------------------------------------------------
-  parameter DEBUG     = 1;
+  parameter DEBUG = 1;
 
   parameter CLK_HALF_PERIOD = 1;
   parameter CLK_PERIOD      = 2 * CLK_HALF_PERIOD;
@@ -109,6 +109,7 @@ module tb_csprng();
   reg           tb_debug_update;
 
   reg [31 : 0]  read_data;
+  reg [7 : 0]   pbyte;
 
 
   //----------------------------------------------------------------
@@ -127,10 +128,9 @@ module tb_csprng();
 
                   .discard(tb_discard),
                   .test_mode(tb_test_mode),
-
-                  .more_seed(tb_more_seed),
                   .security_error(tb_security_error),
 
+                  .more_seed(tb_more_seed),
                   .seed_data(tb_seed_data),
                   .seed_syn(tb_seed_syn),
                   .seed_ack(tb_seed_ack),
@@ -326,13 +326,36 @@ module tb_csprng();
       tb_test_mode    = 0;
 
       tb_seed_syn     = 0;
-      tb_seed_data    = {16{32'h00000000}};
+      tb_seed_data    = {8{64'h0000000000000000}};
       tb_rnd_ack      = 0;
       tb_debug_update = 0;
+
+      pbyte           = 8'h00;
     end
   endtask // init_sim
 
 
+  //----------------------------------------------------------------
+  // seed_generator
+  //
+  // When a seed_syn is observed this process will provide a new
+  // seed to the DUT, assert SYN, wait for ACK and then update
+  // the seed pattern state.
+  //----------------------------------------------------------------
+  always @ (posedge tb_more_seed)
+    begin : seed_generator
+      #(CLK_PERIOD);
+      tb_seed_data = {64{pbyte}};
+      tb_seed_syn  = 1'b1;
+
+      while (!tb_seed_ack)
+        #(CLK_PERIOD);
+
+      tb_seed_syn  = 1'b0;
+      pbyte = pbyte + 8'h01;
+    end
+
+
   //----------------------------------------------------------------
   // tc1_init_csprng()
   //
@@ -381,9 +404,9 @@ module tb_csprng();
       write_word(ADDR_NUM_BLOCKS_LOW, 32'h00000001);
 
       // Start pulling data.
-      tb_cs        = 1'b1;
-      tb_we        = 1'b0;
-      tb_address   = ADDR_RND_DATA;
+      tb_cs      = 1'b1;
+      tb_we      = 1'b0;
+      tb_address = ADDR_RND_DATA;
 
       #(200 * CLK_PERIOD);
 
@@ -392,6 +415,28 @@ module tb_csprng();
   endtask // tc2_reseed_csprng
 
 
+  //----------------------------------------------------------------
+  //----------------------------------------------------------------
+  task test_gen_data();
+    integer i;
+    begin
+      pbyte = 8'h00;
+      i = 0;
+
+      $display("Generating seed patterns.\n");
+
+      while (i < 256)
+        begin
+          tb_seed_data = {64{pbyte}};
+          $display("seed %03d: 0x%064x", i, tb_seed_data);
+          #(CLK_PERIOD);
+          i = i + 1;
+          pbyte = pbyte + 8'h01;
+        end
+    end
+  endtask // test_gen_data
+
+
   //----------------------------------------------------------------
   // csprng_test
   //
@@ -409,6 +454,7 @@ module tb_csprng();
       reset_dut();
       dump_dut_state();
 
+      test_gen_data();
       tc1_init_csprng();
       tc2_reseed_csprng();
 
-- 
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