From 26bc2a2ffb02c9366f5e179f2a97a1221fc05d8c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Joachim=20Stro=CC=88mbergson?= <joachim@secworks.se>
Date: Thu, 26 Mar 2015 12:33:27 +0100
Subject: Cleanup: Combined the clocked processes into one. Changed name of the
 data read register to reflect that it is a hold register. Fixed missing port
 and removed the unneeded assignment.

---
 src/rtl/avalanche_entropy.v | 48 +++++++++++++++++++++------------------------
 1 file changed, 22 insertions(+), 26 deletions(-)

diff --git a/src/rtl/avalanche_entropy.v b/src/rtl/avalanche_entropy.v
index 686dd2d..aeece13 100644
--- a/src/rtl/avalanche_entropy.v
+++ b/src/rtl/avalanche_entropy.v
@@ -94,6 +94,9 @@ module avalanche_entropy(
   //----------------------------------------------------------------
   // Registers including update variables and write enable.
   //----------------------------------------------------------------
+  reg [31 : 0] read_data_hold_reg;
+  reg [31 : 0] read_data_hold_new;
+
   reg          enable_reg;
   reg          enable_new;
   reg          enable_we;
@@ -104,20 +107,16 @@ module avalanche_entropy(
   //----------------------------------------------------------------
   wire [31 : 0]  delta;
 
-  reg [31 : 0]   tmp_read_data;
-  reg [31 : 0]   tmp_read_data_reg;
   reg            tmp_error;
 
 
   //----------------------------------------------------------------
   // Concurrent connectivity for ports etc.
   //----------------------------------------------------------------
-  assign read_data       = tmp_read_data_reg;
+  assign read_data       = read_data_hold_reg;
   assign error           = tmp_error;
   assign security_error  = 0;
 
-  assign entropy_enabled = enable_reg;
-
 
   //----------------------------------------------------------------
   // Core instantiation.
@@ -131,6 +130,7 @@ module avalanche_entropy(
                               .enable(enable_reg),
 
                               .entropy_data(entropy_data),
+                              .entropy_enabled(entropy_enabled),
                               .entropy_valid(entropy_valid),
                               .entropy_ack(entropy_ack),
 
@@ -148,14 +148,16 @@ module avalanche_entropy(
     begin
       if (!reset_n)
         begin
-          enable_reg <= 1;
+          read_data_hold_reg <= 32'h00000000;
+          enable_reg         <= 1;
         end
       else
         begin
+          if (cs)
+            read_data_hold_reg <= read_data_hold_new;
+
           if (enable_we)
-            begin
-              enable_reg <= enable_new;
-            end
+            enable_reg <= enable_new;
         end
     end // reg_update
 
@@ -165,10 +167,10 @@ module avalanche_entropy(
   //----------------------------------------------------------------
   always @*
     begin : api_logic
-      tmp_read_data = 32'h00000000;
-      tmp_error     = 1'b0;
-      enable_new    = 0;
-      enable_we     = 0;
+      read_data_hold_new = 32'h00000000;
+      tmp_error          = 1'b0;
+      enable_new         = 0;
+      enable_we          = 0;
 
       if (cs)
         begin
@@ -193,37 +195,37 @@ module avalanche_entropy(
               case (address)
                 ADDR_NAME0:
                   begin
-                    tmp_read_data = CORE_NAME0;
+                    read_data_hold_new = CORE_NAME0;
                   end
 
                 ADDR_NAME1:
                   begin
-                    tmp_read_data = CORE_NAME1;
+                    read_data_hold_new = CORE_NAME1;
                   end
 
                 ADDR_VERSION:
                   begin
-                    tmp_read_data = CORE_VERSION;
+                    read_data_hold_new = CORE_VERSION;
                   end
 
                 ADDR_CTRL:
                   begin
-                    tmp_read_data = {31'h00000000, enable_reg};
+                    read_data_hold_new = {31'h00000000, enable_reg};
                   end
 
                 ADDR_STATUS:
                   begin
-                    tmp_read_data = {31'h00000000, entropy_valid};
+                    read_data_hold_new = {31'h00000000, entropy_valid};
                    end
 
                 ADDR_ENTROPY:
                   begin
-                    tmp_read_data = entropy_data;
+                    read_data_hold_new = entropy_data;
                   end
 
                 ADDR_DELTA:
                   begin
-                    tmp_read_data = delta;
+                    read_data_hold_new = delta;
                   end
 
                 default:
@@ -235,12 +237,6 @@ module avalanche_entropy(
         end // if (cs)
     end // api_logic
 
-   // register data for eim output
-   always @(posedge clk)
-     begin
-        tmp_read_data_reg <= tmp_read_data;
-     end
-
 endmodule // avalanche_entropy
 
 //======================================================================
-- 
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