From a8662af84800b95fc143930962203191b6bec2fa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Joachim=20Stro=CC=88mbergson?= <joachim@secworks.se>
Date: Wed, 20 May 2015 14:23:27 +0200
Subject: Adding new memories with internal pointers.

---
 src/rtl/blockmem2rptr1w.v | 134 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 134 insertions(+)
 create mode 100644 src/rtl/blockmem2rptr1w.v

(limited to 'src/rtl/blockmem2rptr1w.v')

diff --git a/src/rtl/blockmem2rptr1w.v b/src/rtl/blockmem2rptr1w.v
new file mode 100644
index 0000000..4eb529e
--- /dev/null
+++ b/src/rtl/blockmem2rptr1w.v
@@ -0,0 +1,134 @@
+//======================================================================
+//
+// blockmem2r1wptr.v
+// -----------------
+// Synchronous block memory with two read ports and one write port.
+// For port 1 the address is implicit and instead given by the
+// internal pointer. But write address is explicitly given.
+//
+// The memory is used in the modexp core.
+//
+//
+// Author: Joachim Strombergson
+// 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:
+// - 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.
+//
+// - 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
+// 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.
+//
+//======================================================================
+
+module blockmem2rptr1w(
+                       input wire           clk,
+                       input wire           reset_n,
+
+                       input wire  [07 : 0] read_addr0,
+                       output wire [31 : 0] read_data0,
+
+                       output wire [31 : 0] read_data1,
+
+                       input wire           rst,
+                       input wire           cs,
+                       input wire           wr,
+                       input wire  [07 : 0] write_addr,
+                       input wire  [31 : 0] write_data
+                      );
+
+
+  //----------------------------------------------------------------
+  // Memories and regs including update variables and write enable.
+  //----------------------------------------------------------------
+  reg [31 : 0] mem [0 : 255];
+  reg [31 : 0] tmp_read_data0;
+  reg [31 : 0] tmp_read_data1;
+
+  reg [7 : 0] ptr_reg;
+  reg [7 : 0] ptr_new;
+  reg         ptr_we;
+
+
+  //----------------------------------------------------------------
+  // Concurrent connectivity for ports etc.
+  //----------------------------------------------------------------
+  assign read_data0 = tmp_read_data0;
+  assign read_data1 = tmp_read_data1;
+
+
+  //----------------------------------------------------------------
+  // mem_update
+  //
+  // Clocked update of memory This should cause
+  // the memory to be implemented as a block memory.
+  //----------------------------------------------------------------
+  always @ (posedge clk)
+    begin : mem_update
+      if (wr)
+        mem[write_addr] <= write_data;
+
+      tmp_read_data0 <= mem[read_addr0];
+      tmp_read_data1 <= mem[ptr_reg];
+    end
+
+
+  //----------------------------------------------------------------
+  // reg_update
+  //----------------------------------------------------------------
+  always @ (posedge clk or negedge reset_n)
+    begin : reg_mem_update
+      if (!reset_n)
+        ptr_reg <= 8'h00;
+
+      else
+        if (ptr_we)
+          ptr_reg <= ptr_new;
+    end
+
+
+  //----------------------------------------------------------------
+  // ptr_logic
+  //----------------------------------------------------------------
+  always @*
+    begin : ptr_logic
+      ptr_new = 8'h00;
+      ptr_we  = 1'b0;
+
+      if (rst)
+        begin
+          ptr_new = 8'h00;
+          ptr_we  = 1'b1;
+        end
+
+      if (cs)
+        begin
+          ptr_new = ptr_reg + 1'b1;
+          ptr_we  = 1'b1;
+        end
+    end
+
+endmodule // blockmem2r1wptr
+
+//======================================================================
+// EOF blockmem2r1wptr.v
+//======================================================================
-- 
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