Combined all AES round operations into a single operation for a round.

1 files changed, 25 insertions, 77 deletions

diff --git a/src/rtl/aes_decipher_block.v b/src/rtl/aes_decipher_block.v
index c2304d6..ce34cc8 100644
--- a/src/rtl/aes_decipher_block.v
+++ b/src/rtl/aes_decipher_block.v
@@ -72,9 +72,8 @@ module aes_decipher_block(
 
   localparam CTRL_IDLE  = 3'h0;
   localparam CTRL_INIT  = 3'h1;
-  localparam CTRL_SBOX  = 3'h2;
-  localparam CTRL_MAIN  = 3'h3;
-  localparam CTRL_FINAL = 3'h4;
+  localparam CTRL_MAIN  = 3'h2;
+  localparam CTRL_FINAL = 3'h3;
 
 
   //----------------------------------------------------------------
@@ -192,22 +191,16 @@ module aes_decipher_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_set;
   reg           round_ctr_dec;
 
-  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;
@@ -243,8 +236,8 @@ module aes_decipher_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;
 
 
@@ -259,27 +252,15 @@ module aes_decipher_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;
           dec_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;
@@ -300,68 +281,43 @@ module aes_decipher_block(
   //----------------------------------------------------------------
   always @*
     begin : round_logic
-      reg [127 : 0] old_block, inv_shiftrows_block, inv_mixcolumns_block;
+      reg [127 : 0] subbytes_block, inv_shiftrows_block, inv_mixcolumns_block;
       reg [127 : 0] addkey_block;
 
       inv_shiftrows_block  = 128'h0;
       inv_mixcolumns_block = 128'h0;
       addkey_block         = 128'h0;
       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_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];
+      subbytes_block = {new_sboxw0, new_sboxw1, new_sboxw2, new_sboxw3};
 
-      old_block = {block_w0_reg, block_w1_reg, block_w2_reg, block_w3_reg};
-
-      // Update based on update type.
       case (update_type)
-        // InitRound
         INIT_UPDATE:
           begin
-            old_block           = block;
-            addkey_block        = addroundkey(old_block, round_key);
+            addkey_block        = addroundkey(block, round_key);
             inv_shiftrows_block = inv_shiftrows(addkey_block);
             block_new           = inv_shiftrows_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_we            = 1'b1;
           end
 
         MAIN_UPDATE:
           begin
-            addkey_block         = addroundkey(old_block, round_key);
+            addkey_block         = addroundkey(subbytes_block, round_key);
             inv_mixcolumns_block = inv_mixcolumns(addkey_block);
             inv_shiftrows_block  = inv_shiftrows(inv_mixcolumns_block);
             block_new            = inv_shiftrows_block;
-            block_w0_we          = 1'b1;
-            block_w1_we          = 1'b1;
-            block_w2_we          = 1'b1;
-            block_w3_we          = 1'b1;
+            block_we             = 1'b1;
           end
 
         FINAL_UPDATE:
           begin
-            block_new    = addroundkey(old_block, round_key);
-            block_w0_we  = 1'b1;
-            block_w1_we  = 1'b1;
-            block_w2_we  = 1'b1;
-            block_w3_we  = 1'b1;
+            block_new = addroundkey(subbytes_block, round_key);
+            block_we  = 1'b1;
           end
 
         default:
@@ -431,15 +387,8 @@ module aes_decipher_block(
 
         CTRL_INIT:
           begin
-            update_type   = INIT_UPDATE;
-            dec_ctrl_new  = CTRL_SBOX;
-            dec_ctrl_we   = 1'b1;
-          end
-
-        CTRL_SBOX:
-          begin
-            update_type   = SBOX_UPDATE;
             round_ctr_dec = 1'b1;
+            update_type   = INIT_UPDATE;
             dec_ctrl_new  = CTRL_MAIN;
             dec_ctrl_we   = 1'b1;
           end
@@ -448,9 +397,8 @@ module aes_decipher_block(
           begin
             if (round_ctr_reg > 0)
               begin
+                round_ctr_dec = 1'b1;
                 update_type   = MAIN_UPDATE;
-                dec_ctrl_new  = CTRL_SBOX;
-                dec_ctrl_we   = 1'b1;
               end
             else
               begin