1 files changed, 25 insertions, 74 deletions

diff --git a/src/rtl/aes_encipher_block.v b/src/rtl/aes_encipher_block.v
index f0e42f9..8cac95f 100644
--- a/src/rtl/aes_encipher_block.v
+++ b/src/rtl/aes_encipher_block.v
@@ -66,9 +66,8 @@ module aes_encipher_block(
 
   localparam NO_UPDATE    = 3'h0;
   localparam INIT_UPDATE  = 3'h1;
-  localparam SBOX_UPDATE  = 3'h2;
-  localparam MAIN_UPDATE  = 3'h3;
-  localparam FINAL_UPDATE = 3'h4;
+  localparam MAIN_UPDATE  = 3'h2;
+  localparam FINAL_UPDATE = 3'h3;
 
   localparam CTRL_IDLE  = 3'h0;
   localparam CTRL_INIT  = 3'h1;
@@ -156,22 +155,16 @@ module aes_encipher_block(
   //----------------------------------------------------------------
   // Registers including update variables and write enable.
   //----------------------------------------------------------------
+  reg [127 : 0] block_reg;
+  reg [127 : 0] block_new;
+  reg           block_we;
+
   reg [3 : 0]   round_ctr_reg;
   reg [3 : 0]   round_ctr_new;
   reg           round_ctr_we;
   reg           round_ctr_rst;
   reg           round_ctr_inc;
 
-  reg [127 : 0] block_new;
-  reg [31 : 0]  block_w0_reg;
-  reg [31 : 0]  block_w1_reg;
-  reg [31 : 0]  block_w2_reg;
-  reg [31 : 0]  block_w3_reg;
-  reg           block_w0_we;
-  reg           block_w1_we;
-  reg           block_w2_we;
-  reg           block_w3_we;
-
   reg           ready_reg;
   reg           ready_new;
   reg           ready_we;
@@ -199,8 +192,8 @@ module aes_encipher_block(
   //----------------------------------------------------------------
   // Concurrent connectivity for ports etc.
   //----------------------------------------------------------------
+  assign new_block = block_reg;
   assign round     = round_ctr_reg;
-  assign new_block = {block_w0_reg, block_w1_reg, block_w2_reg, block_w3_reg};
   assign ready     = ready_reg;
 
 
@@ -224,27 +217,15 @@ module aes_encipher_block(
     begin: reg_update
       if (!reset_n)
         begin
-          block_w0_reg  <= 32'h0;
-          block_w1_reg  <= 32'h0;
-          block_w2_reg  <= 32'h0;
-          block_w3_reg  <= 32'h0;
+          block_reg     <= 128'h0;
           round_ctr_reg <= 4'h0;
           ready_reg     <= 1'b1;
           enc_ctrl_reg  <= CTRL_IDLE;
         end
       else
         begin
-          if (block_w0_we)
-            block_w0_reg <= block_new[127 : 096];
-
-          if (block_w1_we)
-            block_w1_reg <= block_new[095 : 064];
-
-          if (block_w2_we)
-            block_w2_reg <= block_new[063 : 032];
-
-          if (block_w3_we)
-            block_w3_reg <= block_new[031 : 000];
+          if (block_we)
+            block_reg <= block_new;
 
           if (round_ctr_we)
             round_ctr_reg <= round_ctr_new;
@@ -265,22 +246,19 @@ module aes_encipher_block(
   //----------------------------------------------------------------
   always @*
     begin : round_logic
-      reg [127 : 0] old_block, shiftrows_block, mixcolumns_block;
+      reg [127 : 0] subbytes_block, shiftrows_block, mixcolumns_block;
       reg [127 : 0] addkey_init_block, addkey_main_block, addkey_final_block;
 
-      block_new   = 128'h0;
-      block_w0_we = 1'b0;
-      block_w1_we = 1'b0;
-      block_w2_we = 1'b0;
-      block_w3_we = 1'b0;
+      block_new = 128'h0;
+      block_we    = 1'b0;
 
-      sboxw0 = block_w0_reg;
-      sboxw1 = block_w1_reg;
-      sboxw2 = block_w2_reg;
-      sboxw3 = block_w3_reg;
+      sboxw0 = block_reg[127 : 96];
+      sboxw1 = block_reg[95  : 64];
+      sboxw2 = block_reg[63  : 32];
+      sboxw3 = block_reg[31  :  0];
 
-      old_block          = {block_w0_reg, block_w1_reg, block_w2_reg, block_w3_reg};
-      shiftrows_block    = shiftrows(old_block);
+      subbytes_block     = {new_sboxw0, new_sboxw1, new_sboxw2, new_sboxw3};
+      shiftrows_block    = shiftrows(subbytes_block);
       mixcolumns_block   = mixcolumns(shiftrows_block);
       addkey_init_block  = addroundkey(block, round_key);
       addkey_main_block  = addroundkey(mixcolumns_block, round_key);
@@ -289,38 +267,20 @@ module aes_encipher_block(
       case (update_type)
         INIT_UPDATE:
           begin
-            block_new    = addkey_init_block;
-            block_w0_we  = 1'b1;
-            block_w1_we  = 1'b1;
-            block_w2_we  = 1'b1;
-            block_w3_we  = 1'b1;
-          end
-
-        SBOX_UPDATE:
-          begin
-            block_new = {new_sboxw0, new_sboxw1, new_sboxw2, new_sboxw3};
-            block_w0_we = 1'b1;
-            block_w1_we = 1'b1;
-            block_w2_we = 1'b1;
-            block_w3_we = 1'b1;
+            block_new = addkey_init_block;
+            block_we  = 1'b1;
           end
 
         MAIN_UPDATE:
           begin
-            block_new    = addkey_main_block;
-            block_w0_we  = 1'b1;
-            block_w1_we  = 1'b1;
-            block_w2_we  = 1'b1;
-            block_w3_we  = 1'b1;
+            block_new = addkey_main_block;
+            block_we  = 1'b1;
           end
 
         FINAL_UPDATE:
           begin
-            block_new    = addkey_final_block;
-            block_w0_we  = 1'b1;
-            block_w1_we  = 1'b1;
-            block_w2_we  = 1'b1;
-            block_w3_we  = 1'b1;
+            block_new = addkey_final_block;
+            block_we  = 1'b1;
           end
 
         default:
@@ -392,13 +352,6 @@ module aes_encipher_block(
           begin
             round_ctr_inc = 1'b1;
             update_type   = INIT_UPDATE;
-            enc_ctrl_new  = CTRL_SBOX;
-            enc_ctrl_we   = 1'b1;
-          end
-
-        CTRL_SBOX:
-          begin
-            update_type   = SBOX_UPDATE;
             enc_ctrl_new  = CTRL_MAIN;
             enc_ctrl_we   = 1'b1;
           end
@@ -409,8 +362,6 @@ module aes_encipher_block(
             if (round_ctr_reg < num_rounds)
               begin
                 update_type   = MAIN_UPDATE;
-                enc_ctrl_new  = CTRL_SBOX;
-                enc_ctrl_we   = 1'b1;
               end
             else
               begin