1 files changed, 70 insertions, 18 deletions
diff --git a/core_selector/src/rtl/math_selector.v b/core_selector/src/rtl/math_selector.v
index 3c29554..93fc8d2 100644
--- a/core_selector/src/rtl/math_selector.v
+++ b/core_selector/src/rtl/math_selector.v
@@ -54,24 +54,76 @@ module math_selector
    );
 
 
-   //
-   // Output Register
-   //
-   reg [31: 0]            tmp_read_data;
-   assign sys_read_data = tmp_read_data;
-
-
-  modexp modexp_inst(
-                     .clk(sys_clk),
-                     .reset_n(~sys_rst),
-                     .cs(sys_ena),
-                     .we(sys_eim_wr),
-                     .address(sys_eim_addr[11 : 0]),
-                     .write_data(sys_write_data),
-                     .read_data(sys_read_data)
-                    );
-
-endmodule // math_selector
+   //----------------------------------------------------------------
+   // Address Decoder
+   //----------------------------------------------------------------
+   // upper 6 bits specify core being addressed
+   wire [ 5: 0]         addr_core_num   = sys_eim_addr[13: 8];
+   // lower 8 bits specify register offset in core
+   wire [ 7: 0]         addr_core_reg   = sys_eim_addr[ 7: 0];
+
+
+   //----------------------------------------------------------------
+   // List of Available Cores
+   //----------------------------------------------------------------
+   // Comment following lines to exclude cores from implementation.
+   `define  USE_CORE_MODEXP
+
+
+   //----------------------------------------------------------------
+   // Core Address Table
+   //----------------------------------------------------------------
+   localparam   CORE_ADDR_MODEXP          = 6'd0;
+   localparam   CORE_ADDR_MODEXP_MODULUS  = 6'd1;
+   localparam   CORE_ADDR_MODEXP_EXPONENT = 6'd2;
+   localparam   CORE_ADDR_MODEXP_MESSAGE  = 6'd3;
+   localparam   CORE_ADDR_MODEXP_RESULT   = 6'd4;
+
+
+   //----------------------------------------------------------------
+   // MODEXP
+   //----------------------------------------------------------------
+   `ifdef USE_CORE_MODEXP
+   wire                 enable_modexp = sys_ena && (addr_core_num >= CORE_ADDR_MODEXP) && (addr_core_num <= CORE_ADDR_MODEXP_RESULT);
+   wire [31: 0]         read_data_modexp;
+
+   modexp modexp_inst
+     (
+      .clk(sys_clk),
+      .reset_n(~sys_rst),
+
+      .cs(enable_modexp & (sys_eim_rd | sys_eim_wr)),
+      .we(sys_eim_wr),
+
+      .address(addr_core_reg),
+      .write_data(sys_write_data),
+      .read_data(read_data_modexp)
+      );
+   `endif
+
+
+   //----------------------------------------------------------------
+   // Output (Read Data) Multiplexor
+   //----------------------------------------------------------------
+   reg [31: 0]          sys_read_data_mux;
+   assign               sys_read_data = sys_read_data_mux;
+
+   always @*
+     //
+   `ifdef USE_CORE_MODEXP
+     if ((addr_core_num >= CORE_ADDR_MODEXP) && (addr_core_num <= CORE_ADDR_MODEXP_RESULT))
+         begin
+            sys_read_data_mux = read_data_modexp;
+         end
+     else
+   `endif
+       //
+       begin
+          sys_read_data_mux = {32{1'b0}};
+       end
+
+
+endmodule
 
 //======================================================================
 // EOF math_selector.v