(1) Locked down API to ignore read or write requests that could leak info or cause incorrect behaviour during processing. (2) Cleaned up API registers and the API.

2 files changed, 68 insertions, 371 deletions

diff --git a/src/rtl/sha256.v b/src/rtl/sha256.v
index 67c8a6b..2ef1a57 100644
--- a/src/rtl/sha256.v
+++ b/src/rtl/sha256.v
@@ -98,7 +98,7 @@ module sha256(
 
   localparam CORE_NAME0     = 32'h73686132; // "sha2"
   localparam CORE_NAME1     = 32'h2d323536; // "-256"
-  localparam CORE_VERSION   = 32'h312e3830; // "1.80"
+  localparam CORE_VERSION   = 32'h312e3832; // "1.82"
 
   localparam MODE_SHA_224   = 1'h0;
   localparam MODE_SHA_256   = 1'h1;
@@ -109,13 +109,9 @@ module sha256(
   //----------------------------------------------------------------
   reg init_reg;
   reg init_new;
-  reg init_we;
-  reg init_set;
 
   reg next_reg;
   reg next_new;
-  reg next_we;
-  reg next_set;
 
   reg mode_reg;
   reg mode_new;
@@ -123,38 +119,8 @@ module sha256(
 
   reg ready_reg;
 
-  reg [31 : 0] block0_reg;
-  reg          block0_we;
-  reg [31 : 0] block1_reg;
-  reg          block1_we;
-  reg [31 : 0] block2_reg;
-  reg          block2_we;
-  reg [31 : 0] block3_reg;
-  reg          block3_we;
-  reg [31 : 0] block4_reg;
-  reg          block4_we;
-  reg [31 : 0] block5_reg;
-  reg          block5_we;
-  reg [31 : 0] block6_reg;
-  reg          block6_we;
-  reg [31 : 0] block7_reg;
-  reg          block7_we;
-  reg [31 : 0] block8_reg;
-  reg          block8_we;
-  reg [31 : 0] block9_reg;
-  reg          block9_we;
-  reg [31 : 0] block10_reg;
-  reg          block10_we;
-  reg [31 : 0] block11_reg;
-  reg          block11_we;
-  reg [31 : 0] block12_reg;
-  reg          block12_we;
-  reg [31 : 0] block13_reg;
-  reg          block13_we;
-  reg [31 : 0] block14_reg;
-  reg          block14_we;
-  reg [31 : 0] block15_reg;
-  reg          block15_we;
+  reg [31 : 0] block_reg [0 : 15];
+  reg          block_we;
 
   reg [255 : 0] digest_reg;
 
@@ -164,8 +130,6 @@ module sha256(
   //----------------------------------------------------------------
   // Wires.
   //----------------------------------------------------------------
-  wire           core_init;
-  wire           core_next;
   wire           core_ready;
   wire [511 : 0] core_block;
   wire [255 : 0] core_digest;
@@ -187,14 +151,10 @@ module sha256(
   //----------------------------------------------------------------
   // Concurrent connectivity for ports etc.
   //----------------------------------------------------------------
-  assign core_init = init_reg;
-
-  assign core_next = next_reg;
-
-  assign core_block = {block0_reg, block1_reg, block2_reg, block3_reg,
-                       block4_reg, block5_reg, block6_reg, block7_reg,
-                       block8_reg, block9_reg, block10_reg, block11_reg,
-                       block12_reg, block13_reg, block14_reg, block15_reg};
+  assign core_block = {block_reg[00], block_reg[01], block_reg[02], block_reg[03],
+                       block_reg[04], block_reg[05], block_reg[06], block_reg[07],
+                       block_reg[08], block_reg[09], block_reg[10], block_reg[11],
+                       block_reg[12], block_reg[13], block_reg[14], block_reg[15]};
 
   assign read_data = tmp_read_data;
   assign error     = tmp_error;
@@ -207,8 +167,8 @@ module sha256(
                    .clk(clk),
                    .reset_n(reset_n),
 
-                   .init(core_init),
-                   .next(core_next),
+                   .init(init_reg),
+                   .next(next_reg),
                    .mode(mode_reg),
 
                    .block(core_block),
@@ -239,46 +199,27 @@ module sha256(
   // asynchronous active low reset.
   //----------------------------------------------------------------
   always @ (posedge clk or negedge reset_n)
-    begin
+    begin : reg_update
+      integer i;
+
       if (!reset_n)
         begin
-          init_reg         <= 1'h0;
-          next_reg         <= 1'h0;
+          for (i = 0 ; i < 16 ; i = i + 1)
+            block_reg[i] <= 32'h0;
+
+          init_reg         <= 0;
+          next_reg         <= 0;
+          ready_reg        <= 0;
           mode_reg         <= MODE_SHA_256;
-          ready_reg        <= 1'h0;
           digest_reg       <= 256'h0;
-          digest_valid_reg <= 1'h0;
-          block0_reg       <= 32'h0;
-          block1_reg       <= 32'h0;
-          block2_reg       <= 32'h0;
-          block3_reg       <= 32'h0;
-          block4_reg       <= 32'h0;
-          block5_reg       <= 32'h0;
-          block6_reg       <= 32'h0;
-          block7_reg       <= 32'h0;
-          block8_reg       <= 32'h0;
-          block9_reg       <= 32'h0;
-          block10_reg      <= 32'h0;
-          block11_reg      <= 32'h0;
-          block12_reg      <= 32'h0;
-          block13_reg      <= 32'h0;
-          block14_reg      <= 32'h0;
-          block15_reg      <= 32'h0;
+          digest_valid_reg <= 0;
         end
       else
         begin
           ready_reg        <= core_ready;
           digest_valid_reg <= core_digest_valid;
-
-          if (init_we)
-            begin
-              init_reg <= init_new;
-            end
-
-          if (next_we)
-            begin
-              next_reg <= next_new;
-            end
+          init_reg         <= init_new;
+          next_reg         <= next_new;
 
           if (mode_we)
             mode_reg <= mode_new;
@@ -288,127 +229,13 @@ module sha256(
               digest_reg <= core_digest;
             end
 
-          if (block0_we)
-            begin
-              block0_reg <= write_data;
-            end
-
-          if (block1_we)
-            begin
-              block1_reg <= write_data;
-            end
-
-          if (block2_we)
-            begin
-              block2_reg <= write_data;
-            end
-
-          if (block3_we)
-            begin
-              block3_reg <= write_data;
-            end
-
-          if (block4_we)
-            begin
-              block4_reg <= write_data;
-            end
-
-          if (block5_we)
-            begin
-              block5_reg <= write_data;
-            end
-
-          if (block6_we)
-            begin
-              block6_reg <= write_data;
-            end
-
-          if (block7_we)
-            begin
-              block7_reg <= write_data;
-            end
-
-          if (block8_we)
-            begin
-              block8_reg <= write_data;
-            end
-
-          if (block9_we)
-            begin
-              block9_reg <= write_data;
-            end
-
-          if (block10_we)
-            begin
-              block10_reg <= write_data;
-            end
-
-          if (block11_we)
-            begin
-              block11_reg <= write_data;
-            end
-
-          if (block12_we)
-            begin
-              block12_reg <= write_data;
-            end
-
-          if (block13_we)
-            begin
-              block13_reg <= write_data;
-            end
-
-          if (block14_we)
-            begin
-              block14_reg <= write_data;
-            end
-
-          if (block15_we)
-            begin
-              block15_reg <= write_data;
-            end
-
+          if (block_we)
+            block_reg[address[3 : 0]] <= write_data;
         end
     end // reg_update
 
 
   //----------------------------------------------------------------
-  // flag_reset
-  //
-  // Logic to reset init and next flags that has been set.
-  //----------------------------------------------------------------
-  always @*
-    begin : flag_reset
-      init_new = 0;
-      init_we  = 0;
-      next_new = 0;
-      next_we  = 0;
-
-      if (init_set)
-        begin
-          init_new = 1;
-          init_we  = 1;
-        end
-      else if (init_reg)
-        begin
-          init_new = 0;
-          init_we  = 1;
-        end
-
-      if (next_set)
-        begin
-          next_new = 1;
-          next_we  = 1;
-        end
-      else if (next_reg)
-        begin
-          next_new = 0;
-          next_we  = 1;
-        end
-    end
-
-
-  //----------------------------------------------------------------
   // api_logic
   //
   // Implementation of the api logic. If cs is enabled will either
@@ -416,26 +243,11 @@ module sha256(
   //----------------------------------------------------------------
   always @*
     begin : api_logic
-      init_set      = 0;
-      next_set      = 0;
+      init_new      = 0;
+      next_new      = 0;
       mode_new      = 0;
       mode_we       = 0;
-      block0_we     = 0;
-      block1_we     = 0;
-      block2_we     = 0;
-      block3_we     = 0;
-      block4_we     = 0;
-      block5_we     = 0;
-      block6_we     = 0;
-      block7_we     = 0;
-      block8_we     = 0;
-      block9_we     = 0;
-      block10_we    = 0;
-      block11_we    = 0;
-      block12_we    = 0;
-      block13_we    = 0;
-      block14_we    = 0;
-      block15_we    = 0;
+      block_we      = 0;
       state0_we     = 0;
       state1_we     = 0;
       state2_we     = 0;
@@ -444,105 +256,65 @@ module sha256(
       state5_we     = 0;
       state6_we     = 0;
       state7_we     = 0;
-
-      tmp_read_data = 32'h00000000;
+      tmp_read_data = 32'h0;
       tmp_error     = 0;
 
       if (cs)
         begin
           if (we)
             begin
-              case (address)
-                // Write operations.
-                ADDR_CTRL:
-                  begin
-                    init_set = write_data[CTRL_INIT_BIT];
-                    next_set = write_data[CTRL_NEXT_BIT];
-                    mode_new = write_data[CTRL_MODE_BIT];
-                    mode_we  = 1;
-                  end
+              if (core_ready)
+                begin
 
-                ADDR_BLOCK0:
-                  block0_we = 1;
+                  if ((address >= ADDR_BLOCK0) && (address <= ADDR_BLOCK15))
+                    block_we = 1;
 
-                ADDR_BLOCK1:
-                  block1_we = 1;
+                  case (address)
+                    ADDR_CTRL:
+                      begin
+                        init_new = write_data[CTRL_INIT_BIT];
+                        next_new = write_data[CTRL_NEXT_BIT];
+                        mode_new = write_data[CTRL_MODE_BIT];
+                        mode_we  = 1;
+                      end
 
-                ADDR_BLOCK2:
-                  block2_we = 1;
+                    ADDR_DIGEST0:
+                      state0_we = 1;
 
-                ADDR_BLOCK3:
-                  block3_we = 1;
+                    ADDR_DIGEST1:
+                      state1_we = 1;
 
-                ADDR_BLOCK4:
-                  block4_we = 1;
+                    ADDR_DIGEST2:
+                      state2_we = 1;
 
-                ADDR_BLOCK5:
-                  block5_we = 1;
+                    ADDR_DIGEST3:
+                      state3_we = 1;
 
-                ADDR_BLOCK6:
-                  block6_we = 1;
+                    ADDR_DIGEST4:
+                      state4_we = 1;
 
-                ADDR_BLOCK7:
-                  block7_we = 1;
+                    ADDR_DIGEST5:
+                      state5_we = 1;
 
-                ADDR_BLOCK8:
-                  block8_we = 1;
+                    ADDR_DIGEST6:
+                      state6_we = 1;
 
-                ADDR_BLOCK9:
-                  block9_we = 1;
+                    ADDR_DIGEST7:
+                      state7_we = 1;
 
-                ADDR_BLOCK10:
-                  block10_we = 1;
-
-                ADDR_BLOCK11:
-                  block11_we = 1;
-
-                ADDR_BLOCK12:
-                  block12_we = 1;
-
-                ADDR_BLOCK13:
-                  block13_we = 1;
-
-                ADDR_BLOCK14:
-                  block14_we = 1;
-
-                ADDR_BLOCK15:
-                  block15_we = 1;
-
-                ADDR_DIGEST0:
-                  state0_we = 1;
-
-                ADDR_DIGEST1:
-                  state1_we = 1;
-
-                ADDR_DIGEST2:
-                  state2_we = 1;
-
-                ADDR_DIGEST3:
-                  state3_we = 1;
-
-                ADDR_DIGEST4:
-                  state4_we = 1;
-
-                ADDR_DIGEST5:
-                  state5_we = 1;
-
-                ADDR_DIGEST6:
-                  state6_we = 1;
-
-                ADDR_DIGEST7:
-                  state7_we = 1;
-
-                default:
-                  begin
-                    tmp_error = 1;
-                  end
-              endcase // case (address)
+                    default:
+                      begin
+                        tmp_error = 1;
+                      end
+                  endcase // case (address)
+                end // if (core_ready)
             end // if (we)
 
           else
             begin
+              if ((address >= ADDR_DIGEST0) && (address <= ADDR_DIGEST7))
+                tmp_read_data = digest_reg[(7 - (address - ADDR_DIGEST0)) * 32 +: 32];
+
               case (address)
                 // Read operations.
                 ADDR_NAME0:
@@ -554,84 +326,9 @@ module sha256(
                 ADDR_VERSION:
                   tmp_read_data = CORE_VERSION;
 
-                ADDR_CTRL:
-                  tmp_read_data = {29'h0, mode_reg, next_reg, init_reg};
-
                 ADDR_STATUS:
                   tmp_read_data = {30'h0, digest_valid_reg, ready_reg};
 
-                ADDR_BLOCK0:
-                  tmp_read_data = block0_reg;
-
-                ADDR_BLOCK1:
-                  tmp_read_data = block1_reg;
-
-                ADDR_BLOCK2:
-                  tmp_read_data = block2_reg;
-
-                ADDR_BLOCK3:
-                  tmp_read_data = block3_reg;
-
-                ADDR_BLOCK4:
-                  tmp_read_data = block4_reg;
-
-                ADDR_BLOCK5:
-                  tmp_read_data = block5_reg;
-
-                ADDR_BLOCK6:
-                  tmp_read_data = block6_reg;
-
-                ADDR_BLOCK7:
-                  tmp_read_data = block7_reg;
-
-                ADDR_BLOCK8:
-                  tmp_read_data = block8_reg;
-
-                ADDR_BLOCK9:
-                  tmp_read_data = block9_reg;
-
-                ADDR_BLOCK10:
-                  tmp_read_data = block10_reg;
-
-                ADDR_BLOCK11:
-                  tmp_read_data = block11_reg;
-
-                ADDR_BLOCK12:
-                  tmp_read_data = block12_reg;
-
-                ADDR_BLOCK13:
-                  tmp_read_data = block13_reg;
-
-                ADDR_BLOCK14:
-                  tmp_read_data = block14_reg;
-
-                ADDR_BLOCK15:
-                  tmp_read_data = block15_reg;
-
-                ADDR_DIGEST0:
-                  tmp_read_data = digest_reg[255 : 224];
-
-                ADDR_DIGEST1:
-                  tmp_read_data = digest_reg[223 : 192];
-
-                ADDR_DIGEST2:
-                  tmp_read_data = digest_reg[191 : 160];
-
-                ADDR_DIGEST3:
-                  tmp_read_data = digest_reg[159 : 128];
-
-                ADDR_DIGEST4:
-                  tmp_read_data = digest_reg[127 :  96];
-
-                ADDR_DIGEST5:
-                  tmp_read_data = digest_reg[95  :  64];
-
-                ADDR_DIGEST6:
-                  tmp_read_data = digest_reg[63  :  32];
-
-                ADDR_DIGEST7:
-                  tmp_read_data = digest_reg[31  :   0];
-
                 default:
                   begin
                     tmp_error = 1;
diff --git a/src/tb/tb_sha256.v b/src/tb/tb_sha256.v
index 01aa66e..99bdcfd 100644
--- a/src/tb/tb_sha256.v
+++ b/src/tb/tb_sha256.v
@@ -182,14 +182,14 @@ module tb_sha256();
 
       $display("Message block:");
       $display("block0  = 0x%08x, block1  = 0x%08x, block2  = 0x%08x,  block3  = 0x%08x",
-               dut.block0_reg, dut.block1_reg, dut.block2_reg, dut.block3_reg);
+               dut.block_reg[0], dut.block_reg[1], dut.block_reg[2], dut.block_reg[3]);
       $display("block4  = 0x%08x, block5  = 0x%08x, block6  = 0x%08x,  block7  = 0x%08x",
-               dut.block4_reg, dut.block5_reg, dut.block6_reg, dut.block7_reg);
+               dut.block_reg[4], dut.block_reg[5], dut.block_reg[6], dut.block_reg[7]);
 
       $display("block8  = 0x%08x, block9  = 0x%08x, block10 = 0x%08x,  block11 = 0x%08x",
-               dut.block8_reg, dut.block9_reg, dut.block10_reg, dut.block11_reg);
+               dut.block_reg[8], dut.block_reg[9], dut.block_reg[10], dut.block_reg[11]);
      $display("block12 = 0x%08x, block13 = 0x%08x, block14 = 0x%08x,  block15 = 0x%08x",
-               dut.block12_reg, dut.block13_reg, dut.block14_reg, dut.block15_reg);
+               dut.block_reg[12], dut.block_reg[13], dut.block_reg[14], dut.block_reg[15]);
       $display("");
 
       $display("Digest:");