//======================================================================
//
// Copyright (c) 2018, 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 ed25519_core_top
(
input wire clk,
input wire rst_n,
input wire next,
output wire valid,
input wire bus_cs,
input wire bus_we,
input wire [ 3:0] bus_addr,
input wire [31:0] bus_data_wr,
output wire [31:0] bus_data_rd
);
//
// Memory Banks
//
localparam [0:0] BUS_ADDR_BANK_K = 1'b0;
localparam [0:0] BUS_ADDR_BANK_QY = 1'b1;
wire [0:0] bus_addr_upper = bus_addr[3:3];
wire [2:0] bus_addr_lower = bus_addr[2:0];
//
// Memories
//
wire [31:0] user_bram_k_rw_dout;
wire [31:0] user_bram_qy_ro_dout;
wire [31:0] user_bram_k_rw_din;
wire [ 2:0] core_bram_k_ro_addr;
wire [ 2:0] core_bram_qy_rw_addr;
wire core_bram_qy_rw_wren;
wire [31:0] core_bram_k_ro_dout;
// wire [31:0] core_bram_qy_rw_dout_unused;
wire [31:0] core_bram_qy_rw_din;
assign user_bram_k_rw_din = bus_data_wr;
assign user_bram_k_rw_wren = bus_cs && bus_we && (bus_addr_upper == BUS_ADDR_BANK_K);
/* write-only memory here to prevent readback of the private key */
bram_1wo_1ro_readfirst #
(
.MEM_WIDTH(32),
.MEM_ADDR_BITS(3)
)
bram_k
( .clk(clk),
.a_addr(bus_addr_lower), .a_out(user_bram_k_rw_dout), .a_wr(user_bram_k_rw_wren), .a_in(user_bram_k_rw_din),
.b_addr(core_bram_k_ro_addr), .b_out(core_bram_k_ro_dout)
);
/* read-write memory here */
bram_1rw_1ro_readfirst #
(
.MEM_WIDTH(32),
.MEM_ADDR_BITS(3)
)
bram_qy
(
.clk(clk),
.a_addr(core_bram_qy_rw_addr), .a_out( ), .a_wr(core_bram_qy_rw_wren), .a_in(core_bram_qy_rw_din),
.b_addr(bus_addr_lower), .b_out(user_bram_qy_ro_dout)
);
//
// Curve Base Point Multiplier
//
reg next_dly;
always @(posedge clk) next_dly <= next;
wire next_trig = next && !next_dly;
ed25519_base_point_multiplier ed25519_base_point_multiplier_inst
(
.clk (clk),
.rst_n (rst_n),
.ena (next_trig),
.rdy (valid),
.k_addr (core_bram_k_ro_addr),
.qy_addr (core_bram_qy_rw_addr),
.qy_wren (core_bram_qy_rw_wren),
.k_din (core_bram_k_ro_dout),
.qy_dout (core_bram_qy_rw_din)
);
//
// Output Selector
//
reg [0:0] bus_addr_upper_dly;
always @(posedge clk) bus_addr_upper_dly <= bus_addr_upper;
reg [31: 0] bus_data_rd_mux;
assign bus_data_rd = bus_data_rd_mux;
always @(*)
//
case (bus_addr_upper_dly)
//
BUS_ADDR_BANK_K: bus_data_rd_mux = user_bram_k_rw_dout;
BUS_ADDR_BANK_QY: bus_data_rd_mux = user_bram_qy_ro_dout;
//
endcase
endmodule
