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//======================================================================
//
// 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 modexps6_wrapper
(
input wire clk,
input wire reset_n,
input wire cs,
input wire we,
input wire [9: 0] address,
input wire [31: 0] write_data,
output wire [31: 0] read_data
);
//
// Address Decoder
//
localparam ADDR_MSB_REGS = 1'b0;
localparam ADDR_MSB_CORE = 1'b1;
wire address_msb = address[9];
wire [8: 0] address_lsb = address[8:0];
//
// Output Mux
//
wire [31: 0] read_data_regs;
wire [31: 0] read_data_core;
//
// Registers
//
localparam ADDR_NAME0 = 9'h000;
localparam ADDR_NAME1 = 9'h001;
localparam ADDR_VERSION = 9'h002;
localparam ADDR_CONTROL = 9'h008; // {next, init}
localparam ADDR_STATUS = 9'h009; // {valid, ready}
localparam ADDR_MODE = 9'h010; // 0 = slow secure, 1 = fast unsafe (public)
localparam ADDR_MODULUS_BITS = 9'h011; //
localparam ADDR_EXPONENT_BITS = 9'h012; //
localparam ADDR_GPIO_REG = 9'h020; //
localparam CONTROL_INIT_BIT = 0;
localparam CONTROL_NEXT_BIT = 1;
localparam STATUS_READY_BIT = 0;
localparam STATUS_VALID_BIT = 1;
localparam CORE_NAME0 = 32'h6D6F6465; // "mode"
localparam CORE_NAME1 = 32'h78707336; // "xps6"
localparam CORE_VERSION = 32'h302E3130; // "0.10"
//
// Registers
//
reg [1: 0] reg_control;
reg reg_mode;
reg [12: 0] reg_modulus_width;
reg [12: 0] reg_exponent_width;
reg [31: 0] reg_gpio;
//
// Wires
//
wire [1: 0] reg_status;
//
// ModExpS6
//
modexps6_top #
(
.MAX_MODULUS_WIDTH (4096)
)
modexps6_core
(
.clk (clk),
.init (reg_control[CONTROL_INIT_BIT]),
.ready (reg_status[STATUS_READY_BIT]),
.next (reg_control[CONTROL_NEXT_BIT]),
.valid (reg_status[STATUS_VALID_BIT]),
.modulus_width (reg_modulus_width),
.exponent_width (reg_exponent_width),
.fast_public_mode (reg_mode),
.bus_cs (cs && (address_msb == ADDR_MSB_CORE)),
.bus_we (we),
.bus_addr (address_lsb),
.bus_data_wr (write_data),
.bus_data_rd (read_data_core)
);
//
// Read Latch
//
reg [31: 0] tmp_read_data;
//
// Read/Write Interface
//
always @(posedge clk)
//
if (!reset_n) begin
//
reg_control <= 2'b00;
reg_mode <= 1'b0;
reg_modulus_width <= 13'd1024;
reg_exponent_width <= 13'd1024;
//
end else if (cs && (address_msb == ADDR_MSB_REGS)) begin
//
if (we) begin
//
// Write Handler
//
case (address_lsb)
//
ADDR_CONTROL: reg_control <= write_data[1: 0];
ADDR_MODE: reg_mode <= write_data[0];
ADDR_MODULUS_BITS: reg_modulus_width <= write_data[12: 0];
ADDR_EXPONENT_BITS: reg_exponent_width <= write_data[12: 0];
ADDR_GPIO_REG: reg_gpio <= write_data;
//
endcase
//
end else begin
//
// Read Handler
//
case (address)
//
ADDR_NAME0: tmp_read_data <= CORE_NAME0;
ADDR_NAME1: tmp_read_data <= CORE_NAME1;
ADDR_VERSION: tmp_read_data <= CORE_VERSION;
ADDR_CONTROL: tmp_read_data <= {{30{1'b0}}, reg_control};
ADDR_STATUS: tmp_read_data <= {{30{1'b0}}, reg_status};
ADDR_MODE: tmp_read_data <= {{31{1'b0}}, reg_mode};
ADDR_MODULUS_BITS: tmp_read_data <= {{19{1'b0}}, reg_modulus_width};
ADDR_EXPONENT_BITS: tmp_read_data <= {{19{1'b0}}, reg_exponent_width};
ADDR_GPIO_REG: tmp_read_data <= reg_gpio;
//
default: tmp_read_data <= 32'h00000000;
//
endcase
//
end
//
end
//
// Register / Core Memory Selector
//
reg address_msb_last;
always @(posedge clk) address_msb_last = address_msb;
reg [31: 0] read_data_mux;
assign read_data = read_data_mux;
always @(*)
//
case (address_msb_last)
//
ADDR_MSB_REGS: read_data_mux = tmp_read_data;
ADDR_MSB_CORE: read_data_mux = read_data_core;
//
endcase
endmodule
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