//======================================================================
//
// math_selector.v
// ---------------
// Selector of math cores. Currently there is only one core in math -
// the modexp core. That core uses 12 bits and we simply ignore the
// top two bits of the address. If we add more math cores we will
// use these bits to select cores here.
//
//
//
// Authors: Joachim Strombergson, Paul Selkirk, Pavel Shatov
// Copyright (c) 2014-2015, 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 math_selector
(
input wire sys_clk,
input wire sys_rst_n,
input wire sys_ena,
input wire [13: 0] sys_eim_addr,
input wire sys_eim_wr,
input wire sys_eim_rd,
output wire [31 : 0] sys_read_data,
input wire [31 : 0] sys_write_data
);
//----------------------------------------------------------------
// Address Decoder
//----------------------------------------------------------------
// upper 2 bits specify core being addressed
wire [ 1: 0] core_select = sys_eim_addr[13: 12];
// lower 12 bits specify addresses within the selected core.
wire [11: 0] core_addr = sys_eim_addr[11: 0];
//----------------------------------------------------------------
// List of Available Cores
//----------------------------------------------------------------
// Comment following lines to exclude cores from implementation.
`define USE_CORE_MODEXP
//----------------------------------------------------------------
// Core Address Table
//----------------------------------------------------------------
localparam CORE_MODEXP = 2'd0;
//----------------------------------------------------------------
// MODEXP
//----------------------------------------------------------------
`ifdef USE_CORE_MODEXP
wire enable_modexp = sys_ena && (core_select == CORE_MODEXP);
wire [31: 0] read_data_modexp;
modexp modexp_inst
(
.clk(sys_clk),
.reset_n(sys_rst_n),
.cs(enable_modexp & (sys_eim_rd | sys_eim_wr)),
.we(sys_eim_wr),
.address(core_addr),
.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 (core_select == CORE_MODEXP)
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
//======================================================================
