Introduced the explicit exponent length improvement to baseline before perfopt. Added testcases with operands > 1024 bits.

2 files changed, 767 insertions, 66 deletions

diff --git a/src/rtl/modexp_core.v b/src/rtl/modexp_core.v
index b8c4403..6dd1570 100644
--- a/src/rtl/modexp_core.v
+++ b/src/rtl/modexp_core.v
@@ -236,6 +236,8 @@ module modexp_core(
   reg           residue_valid_int_validated;
 
   wire [7 : 0]  length_m1;
+  wire [7 : 0]  modulus_length_m1;
+  wire [7 : 0]  exponent_length_m1;
 
 
   //----------------------------------------------------------------
@@ -244,7 +246,9 @@ module modexp_core(
   assign ready  = ready_reg;
   assign cycles = {cycle_ctr_high_reg, cycle_ctr_low_reg};
 
-  assign length_m1 = modulus_length - 8'h1;
+
+  assign modulus_length_m1  = modulus_length - 8'h1;
+  assign exponent_length_m1 = exponent_length - 8'h1;
 
 
   //----------------------------------------------------------------
@@ -485,10 +489,10 @@ module modexp_core(
       one_new   = 32'h00000000;
       b_one_new = 32'h00000000;
 
-      if (montprod_opa_addr == length_m1)
+      if (montprod_opa_addr == modulus_length_m1)
         one_new = 32'h00000001;
 
-      if (montprod_opb_addr == length_m1)
+      if (montprod_opb_addr == modulus_length_m1)
         b_one_new = 32'h00000001;
     end
 
@@ -634,7 +638,7 @@ module modexp_core(
       loop_counter_new = 13'b0;
       loop_counter_we  = 1'b0;
 
-      if (loop_counter_reg == {length_m1, 5'b11111})
+      if (loop_counter_reg == {exponent_length_m1, 5'b11111})
         last_iteration = 1'b1;
       else
         last_iteration = 1'b0;
@@ -668,7 +672,7 @@ module modexp_core(
     begin : exponent_process
       // Accessing new instead of reg - pick up update at
       // CTRL_ITERATE_NEW to remove a pipeline stall.
-      E_word_index  = length_m1 - loop_counter_new[ 12 : 5 ];
+      E_word_index  = exponent_length_m1 - loop_counter_new[ 12 : 5 ];
 
       E_bit_index   = loop_counter_reg[ 04 : 0 ];
 
diff --git a/src/tb/tb_modexp.v b/src/tb/tb_modexp.v
index c2ab7fb..90506d8 100644
--- a/src/tb/tb_modexp.v
+++ b/src/tb/tb_modexp.v
@@ -6,33 +6,33 @@
 //
 //
 // Author: Joachim Strombergson, Peter Magnusson
-// Copyright (c) 2015, Assured AB
-// All rights reserved.
+// Copyright (c) 2015, NORDUnet A/S All rights reserved.
 //
-// Redistribution and use in source and binary forms, with or
-// without modification, are permitted provided that the following
-// conditions are met:
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+// - Redistributions of source code must retain the above copyright notice,
+//   this list of conditions and the following disclaimer.
 //
-// 1. Redistributions of source code must retain the above copyright
-//    notice, this list of conditions and the following disclaimer.
+// - Redistributions in binary form must reproduce the above copyright
+//   notice, this list of conditions and the following disclaimer in the
+//   documentation and/or other materials provided with the distribution.
 //
-// 2. Redistributions in binary form must reproduce the above copyright
-//    notice, this list of conditions and the following disclaimer in
-//    the documentation and/or other materials provided with the
-//    distribution.
+// - Neither the name of the NORDUnet nor the names of its contributors may
+//   be used to endorse or promote products derived from this software
+//   without specific prior written permission.
 //
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
-// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
-// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
-// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
-// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
-// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
-// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
-// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
-// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
-// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+// PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+// TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 //
 //======================================================================
 
@@ -256,8 +256,8 @@ module tb_modexp();
                dut.core_inst.ready_reg, dut.start_reg, dut.start_new);
       $display("residue_valid = 0x%01x", dut.core_inst.residue_valid_reg);
       $display("loop_counter_reg = 0x%08x", dut.core_inst.loop_counter_reg);
-      $display("exponent_length_reg = 0x%02x, modulus_length_reg = 0x%02x length_m1 = 0x%02x",
-               dut.exponent_length_reg, dut.modulus_length_reg, dut.core_inst.length_m1);
+      $display("exponent_length_reg = 0x%02x exponent_length_m1 = 0x%02x modulus_length_reg = 0x%02x modulus_length_m1 = 0x%02x",
+               dut.exponent_length_reg,  dut.core_inst.exponent_length_m1, dut.modulus_length_reg, dut.core_inst.modulus_length_m1);
       $display("ctrl_reg = 0x%04x", dut.core_inst.modexp_ctrl_reg);
       $display("");
     end
@@ -786,26 +786,28 @@ module tb_modexp();
       tc_ctr = tc_ctr + 1;
       $display("autogenerated_BASIC_128bit");
 
-      write_word({GENERAL_PREFIX, ADDR_MESSAGE_PTR_RST}, 32'h00000000);
-      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h29462882);
-      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h12caa2d5);
-      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hb80e1c66);
-      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h1006807f);
-
       write_word({GENERAL_PREFIX, ADDR_EXPONENT_PTR_RST}, 32'h00000000);
       write_word({GENERAL_PREFIX, ADDR_EXPONENT_DATA}, 32'h3285c343);
       write_word({GENERAL_PREFIX, ADDR_EXPONENT_DATA}, 32'h2acbcb0f);
       write_word({GENERAL_PREFIX, ADDR_EXPONENT_DATA}, 32'h4d023228);
       write_word({GENERAL_PREFIX, ADDR_EXPONENT_DATA}, 32'h2ecc73db);
 
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h29462882);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h12caa2d5);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hb80e1c66);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h1006807f);
+
       write_word({GENERAL_PREFIX, ADDR_MODULUS_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h00000000);
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h267d2f2e);
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h51c216a7);
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hda752ead);
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h48d22d89);
 
       write_word({GENERAL_PREFIX, ADDR_EXPONENT_LENGTH}, 32'h00000004);
-      write_word({GENERAL_PREFIX, ADDR_MODULUS_LENGTH}, 32'h00000004);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_LENGTH}, 32'h00000005);
 
       start_test_cycle_ctr();
 
@@ -816,10 +818,11 @@ module tb_modexp();
       stop_test_cycle_ctr();
 
       write_word({GENERAL_PREFIX, ADDR_RESULT_PTR_RST}, 32'h00000000);
-      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h0ddc404d, read_data); //TEMPLATE_EXPECTED_VALUES
-      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h91600596, read_data); //TEMPLATE_EXPECTED_VALUES
-      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h7425a8d8, read_data); //TEMPLATE_EXPECTED_VALUES
-      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha066ca56, read_data); //TEMPLATE_EXPECTED_VALUES
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h00000000, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h0ddc404d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h91600596, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h7425a8d8, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha066ca56, read_data);
 
       if (success !== 1)
         begin
@@ -833,6 +836,57 @@ module tb_modexp();
 
 
   //----------------------------------------------------------------
+  // e64bit_64bit_modulus()
+  //----------------------------------------------------------------
+  task e64bit_64bit_modulus();
+    reg [31 : 0] read_data;
+    begin
+      success = 32'h1;
+      tc_ctr = tc_ctr + 1;
+      $display("Test with 64 bit exponent and 64 bit modulus.");
+
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_DATA}, 32'h12345678);
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_DATA}, 32'h97543211);
+
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hfeababab);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hdeadbeef);
+
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffee);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hbeefbeef);
+
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_LENGTH}, 32'h00000002);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_LENGTH}, 32'h00000003);
+
+      start_test_cycle_ctr();
+
+      // Start processing and wait for ready.
+      write_word({GENERAL_PREFIX, ADDR_CTRL}, 32'h00000001);
+      wait_ready();
+
+      stop_test_cycle_ctr();
+
+      write_word({GENERAL_PREFIX, ADDR_RESULT_PTR_RST}, 32'h00000000);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h00000000, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'he52c5b9f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h85de87eb, read_data);
+
+      if (success !== 1)
+        begin
+          $display("*** ERROR: 64 bit exponent and 64 bit_modulus was NOT successful.");
+          error_ctr = error_ctr + 1;
+        end
+      else
+        $display("*** 64 bit exponent and 64 bit modulus success.");
+    end
+  endtask // e64bit_64bit_modulus
+
+
+  //----------------------------------------------------------------
   // e65537_64bit_modulus()
   //----------------------------------------------------------------
   task e65537_64bit_modulus();
@@ -846,15 +900,17 @@ module tb_modexp();
       write_word({GENERAL_PREFIX, ADDR_EXPONENT_DATA}, 32'h00010001);
 
       write_word({GENERAL_PREFIX, ADDR_MODULUS_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h00000000);
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hf077656f);
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h3bf9e69b);
 
       write_word({GENERAL_PREFIX, ADDR_MESSAGE_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h00000000);
       write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hb6684dc3);
       write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h79a5824b);
 
       write_word({GENERAL_PREFIX, ADDR_EXPONENT_LENGTH}, 32'h00000001);
-      write_word({GENERAL_PREFIX, ADDR_MODULUS_LENGTH}, 32'h00000002);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_LENGTH}, 32'h00000003);
 
       start_test_cycle_ctr();
 
@@ -865,8 +921,9 @@ module tb_modexp();
       stop_test_cycle_ctr();
 
       write_word({GENERAL_PREFIX, ADDR_RESULT_PTR_RST}, 32'h00000000);
-      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h419a024f, read_data);
-      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hdddf178e, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h00000000, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h132d8e17, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hdd4d85a4, read_data);
 
       if (success !== 1)
         begin
@@ -880,6 +937,56 @@ module tb_modexp();
 
 
   //----------------------------------------------------------------
+  // e65537_64bit_modulus_elength()
+  //----------------------------------------------------------------
+  task e65537_64bit_modulus_elength();
+    reg [31 : 0] read_data;
+    begin
+      success = 32'h1;
+      tc_ctr = tc_ctr + 1;
+      $display("Test with e = 65537 and 64 bit modulus, explicit exponent length.");
+
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_DATA}, 32'h00010001);
+
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hf077656f);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h3bf9e69b);
+
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hb6684dc3);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h79a5824b);
+
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_LENGTH}, 32'h00000001);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_LENGTH}, 32'h00000003);
+
+      start_test_cycle_ctr();
+
+      // Start processing and wait for ready.
+      write_word({GENERAL_PREFIX, ADDR_CTRL}, 32'h00000001);
+      wait_ready();
+
+      stop_test_cycle_ctr();
+
+      write_word({GENERAL_PREFIX, ADDR_RESULT_PTR_RST}, 32'h00000000);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h00000000, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h132d8e17, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hdd4d85a4, read_data);
+
+      if (success !== 1)
+        begin
+          $display("*** ERROR: e65537_64bit_modulus with explicit elength was NOT successful.");
+          error_ctr = error_ctr + 1;
+        end
+      else
+        $display("*** e65537_64bit_modulus success.");
+    end
+  endtask // e65537_64bit_modulus_elength
+
+
+  //----------------------------------------------------------------
   // e65537_128bit_modulus()
   //----------------------------------------------------------------
   task e65537_128bit_modulus();
@@ -893,19 +1000,21 @@ module tb_modexp();
       write_word({GENERAL_PREFIX, ADDR_EXPONENT_DATA}, 32'h00010001);
 
       write_word({GENERAL_PREFIX, ADDR_MODULUS_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h00000000);
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hf5e8eee0);
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hc06b048a);
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h964b2105);
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h2c36ad6b);
 
       write_word({GENERAL_PREFIX, ADDR_MESSAGE_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h00000000);
       write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h956e61b3);
       write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h27997bc4);
       write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h94e7e5c9);
       write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hb53585cf);
 
       write_word({GENERAL_PREFIX, ADDR_EXPONENT_LENGTH}, 32'h00000001);
-      write_word({GENERAL_PREFIX, ADDR_MODULUS_LENGTH}, 32'h00000004);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_LENGTH}, 32'h00000005);
 
       start_test_cycle_ctr();
 
@@ -916,10 +1025,11 @@ module tb_modexp();
       stop_test_cycle_ctr();
 
       write_word({GENERAL_PREFIX, ADDR_RESULT_PTR_RST}, 32'h00000000);
-      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1e97bff8, read_data);
-      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h60029e6e, read_data);
-      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hedaef85e, read_data);
-      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hfb0c6562, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h00000000, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h9c6d322c, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h25ab8bd3, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4aa80100, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hf0f3a02c, read_data);
 
       if (success !== 1)
         begin
@@ -947,17 +1057,8 @@ module tb_modexp();
       write_word({GENERAL_PREFIX, ADDR_EXPONENT_PTR_RST}, 32'h00000000);
       write_word({GENERAL_PREFIX, ADDR_EXPONENT_DATA}, 32'h00010001);
 
-      write_word({GENERAL_PREFIX, ADDR_MESSAGE_PTR_RST}, 32'h00000000);
-      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hf169d36e);
-      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hbe2ce61d);
-      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hc2e87809);
-      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h4fed15c3);
-      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h7c70eac5);
-      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'ha123e643);
-      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h299b36d2);
-      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h788e583b);
-
       write_word({GENERAL_PREFIX, ADDR_MODULUS_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h00000000);
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hf169d36e);
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hbe2ce61d);
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hc2e87809);
@@ -967,8 +1068,19 @@ module tb_modexp();
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h299b36d2);
       write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h788e583b);
 
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hf169d36e);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hbe2ce61d);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hc2e87809);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h4fed15c3);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h7c70eac5);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'ha123e643);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h299b36d2);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h788e583a);
+
       write_word({GENERAL_PREFIX, ADDR_EXPONENT_LENGTH}, 32'h00000001);
-      write_word({GENERAL_PREFIX, ADDR_MODULUS_LENGTH}, 32'h00000008);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_LENGTH}, 32'h00000009);
 
       start_test_cycle_ctr();
 
@@ -979,10 +1091,15 @@ module tb_modexp();
       stop_test_cycle_ctr();
 
       write_word({GENERAL_PREFIX, ADDR_RESULT_PTR_RST}, 32'h00000000);
-      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h0ddc404d, read_data); //TEMPLATE_EXPECTED_VALUES
-      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h91600596, read_data); //TEMPLATE_EXPECTED_VALUES
-      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h7425a8d8, read_data); //TEMPLATE_EXPECTED_VALUES
-      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha066ca56, read_data); //TEMPLATE_EXPECTED_VALUES
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h00000000, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hf169d36e, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hbe2ce61d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hc2e87809, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4fed15c3, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h7c70eac5, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha123e643, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h299b36d2, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h788e583a, read_data);
 
       if (success !== 1)
         begin
@@ -996,6 +1113,582 @@ module tb_modexp();
 
 
   //----------------------------------------------------------------
+  // e65537_1024bit_modulus()
+  //
+  // Task that tests modexp with small exponent and
+  //  2048 bit modulus.
+  //----------------------------------------------------------------
+  task e65537_1024bit_modulus();
+    reg [31 : 0] read_data;
+    begin
+      success = 32'h1;
+      tc_ctr = tc_ctr + 1;
+      $display("Test with e = 65537 and 1024 bit modulus.");
+
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_DATA}, 32'h00010001);
+
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+
+
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_LENGTH}, 32'h00000001);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_LENGTH}, 32'h00000021);
+
+      start_test_cycle_ctr();
+
+      // Start processing and wait for ready.
+      write_word({GENERAL_PREFIX, ADDR_CTRL}, 32'h00000001);
+      wait_ready();
+
+      stop_test_cycle_ctr();
+
+      write_word({GENERAL_PREFIX, ADDR_RESULT_PTR_RST}, 32'h00000000);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h00000000, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h45d55343, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'ha0971add, read_data);
+
+      if (success !== 1)
+        begin
+          $display("*** ERROR: e65537_1024bit_modulus was NOT successful.");
+          error_ctr = error_ctr + 1;
+        end
+      else
+        $display("*** e65537_1024bit_modulus success.");
+    end
+  endtask // e65537_1024bit_modulus
+
+
+  //----------------------------------------------------------------
+  // e65537_2048bit_modulus()
+  //
+  // Task that tests modexp with small exponent and
+  //  1536 bit modulus.
+  //----------------------------------------------------------------
+  task e65537_1536bit_modulus();
+    reg [31 : 0] read_data;
+    begin
+      success = 32'h1;
+      tc_ctr = tc_ctr + 1;
+      $display("Test with e = 65537 and 1536 bit modulus.");
+
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_DATA}, 32'h00010001);
+
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+
+
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_LENGTH}, 32'h00000001);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_LENGTH}, 32'h00000031);
+
+      start_test_cycle_ctr();
+
+      // Start processing and wait for ready.
+      write_word({GENERAL_PREFIX, ADDR_CTRL}, 32'h00000001);
+      wait_ready();
+
+      stop_test_cycle_ctr();
+
+      write_word({GENERAL_PREFIX, ADDR_RESULT_PTR_RST}, 32'h00000000);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h00000000, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h4ade4f46, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h02cb4a2f, read_data);
+
+      if (success !== 1)
+        begin
+          $display("*** ERROR: e65537_1536bit_modulus was NOT successful.");
+          error_ctr = error_ctr + 1;
+        end
+      else
+        $display("*** e65537_1536bit_modulus success.");
+    end
+  endtask // e65537_1536bit_modulus
+
+
+  //----------------------------------------------------------------
+  // e65537_2048bit_modulus()
+  //
+  // Task that tests modexp with small exponent and
+  //  2048 bit modulus.
+  //----------------------------------------------------------------
+  task e65537_2048bit_modulus();
+    reg [31 : 0] read_data;
+    begin
+      success = 32'h1;
+      tc_ctr = tc_ctr + 1;
+      $display("Test with e = 65537 and 2048 bit modulus.");
+
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_DATA}, 32'h00010001);
+
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_DATA}, 32'hffeeffef);
+
+
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_PTR_RST}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'h00000000);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hffaabbcc);
+      write_word({GENERAL_PREFIX, ADDR_MESSAGE_DATA}, 32'hddeeffff);
+
+      write_word({GENERAL_PREFIX, ADDR_EXPONENT_LENGTH}, 32'h00000001);
+      write_word({GENERAL_PREFIX, ADDR_MODULUS_LENGTH}, 32'h00000041);
+
+      start_test_cycle_ctr();
+
+      // Start processing and wait for ready.
+      write_word({GENERAL_PREFIX, ADDR_CTRL}, 32'h00000001);
+      wait_ready();
+
+      stop_test_cycle_ctr();
+
+      write_word({GENERAL_PREFIX, ADDR_RESULT_PTR_RST}, 32'h00000000);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h00000000, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'h1662df7d, read_data);
+      read_word({GENERAL_PREFIX, ADDR_RESULT_DATA}); read_data = tb_read_data; success = success & assertEquals(32'hcbe66eb1, read_data);
+
+      if (success !== 1)
+        begin
+          $display("*** ERROR: e65537_2048bit_modulus was NOT successful.");
+          error_ctr = error_ctr + 1;
+        end
+      else
+        $display("*** e65537_2048bit_modulus success.");
+    end
+  endtask // e65537_2048bit_modulus
+
+
+  //----------------------------------------------------------------
   // rob_dec_1024()
   //
   // Task that tests modexp with 1024 bit decipher/sign with
@@ -1373,12 +2066,16 @@ module tb_modexp();
 //      tc3();
 //      autogenerated_BASIC_33bit();
 //      autogenerated_BASIC_128bit();
+//      e64bit_64bit_modulus();
 //      e65537_64bit_modulus();
+//      e65537_64bit_modulus_elength();
 //      e65537_128bit_modulus();
 //      e65537_256bit_modulus();
-
+//      e65537_1024bit_modulus();
+      e65537_1536bit_modulus();
+//      e65537_2048bit_modulus();
 //      rob_dec_1024();
-      rob_enc_1024();
+//      rob_enc_1024();
 
       display_test_results();