//======================================================================
//
// residue.v
// ---------
// Modulus 2**2N residue calculator for montgomery calculations.
//
// m_residue_2_2N_array( N, M, Nr)
// Nr = 00...01 ; Nr = 1 == 2**(2N-2N)
// for (int i = 0; i < 2 * N; i++)
// Nr = Nr shift left 1
// if (Nr less than M) continue;
// Nr = Nr - M
// return Nr
//
//
//
// Author: Peter Magnusson
// 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 residue(
input wire clk,
input wire reset_n,
input wire calculate,
output wire ready,
input wire [07 : 0] nn,
input wire [07 : 0] length,
output wire [07 : 0] opa_rd_addr,
input wire [31 : 0] opa_rd_data,
output wire [07 : 0] opa_wr_addr,
output wire [31 : 0] opa_wr_data,
output wire opa_wr_we,
output wire [07 : 0] opm_addr,
input wire [31 : 0] opm_data
);
//----------------------------------------------------------------
// Internal constant and parameter definitions.
//----------------------------------------------------------------
localparam CTRL_IDLE = 4'h0;
localparam CTRL_INIT = 4'h1;
localparam CTRL_INIT_STALL = 4'h2;
localparam CTRL_SHL = 4'h3;
localparam CTRL_SHL_STALL = 4'h4;
localparam CTRL_COMPARE = 4'h5;
localparam CTRL_COMPARE_STALL = 4'h6;
localparam CTRL_SUB = 4'h7;
localparam CTRL_SUB_STALL = 4'h8;
localparam CTRL_LOOP = 4'h9;
//----------------------------------------------------------------
// Registers including update variables and write enable.
//----------------------------------------------------------------
reg [07 : 0] opa_rd_addr_reg;
reg [07 : 0] opa_wr_addr_reg;
reg [31 : 0] opa_wr_data_reg;
reg opa_wr_we_reg;
reg [07 : 0] opm_addr_reg;
reg ready_reg;
reg ready_new;
reg ready_we;
reg [03 : 0] residue_ctrl_reg;
reg [03 : 0] residue_ctrl_new;
reg residue_ctrl_we;
reg reset_word_index;
reg reset_n_counter;
reg [07 : 0] word_index;
//----------------------------------------------------------------
// Concurrent connectivity for ports etc.
//----------------------------------------------------------------
assign opa_rd_addr = opa_rd_addr_reg;
assign opa_wr_addr = opa_wr_addr_reg;
assign opa_wr_data = opa_wr_data_reg;
assign opm_addr = opm_addr_reg;
assign ready = ready_reg;
//----------------------------------------------------------------
// reg_update
//----------------------------------------------------------------
always @ (posedge clk or negedge reset_n)
begin
if (!reset_n)
begin
residue_ctrl_reg <= CTRL_IDLE;
end
else
begin
if (residue_ctrl_we)
residue_ctrl_reg <= residue_ctrl_new;
end
end // reg_update
//----------------------------------------------------------------
//----------------------------------------------------------------
always @*
begin : process_1_to_2n
end
//----------------------------------------------------------------
//----------------------------------------------------------------
always @*
begin : word_index_process
end
//----------------------------------------------------------------
// residue_ctrl
//
// Control FSM for residue
//----------------------------------------------------------------
always @*
begin : residue_ctrl
ready_new = 1'b0;
ready_we = 1'b0;
residue_ctrl_new = CTRL_IDLE;
residue_ctrl_we = 1'b0;
reset_word_index = 1'b0;
reset_n_counter = 1'b0;
case (residue_ctrl_reg)
CTRL_IDLE:
if (calculate)
begin
ready_new = 1'b0;
ready_we = 1'b1;
residue_ctrl_new = CTRL_INIT;
residue_ctrl_we = 1'b1;
reset_word_index = 1'b1;
end
CTRL_INIT:
if (word_index == 8'h0)
begin
residue_ctrl_new = CTRL_INIT_STALL;
residue_ctrl_we = 1'b1;
end
CTRL_INIT_STALL:
begin
reset_word_index = 1'b1;
reset_n_counter = 1'b1;
residue_ctrl_new = CTRL_COMPARE;
residue_ctrl_we = 1'b1;
end
CTRL_COMPARE:
begin
end
CTRL_COMPARE_STALL:
begin
end
CTRL_SUB:
begin
end
CTRL_SUB_STALL:
begin
end
CTRL_SHL:
begin
end
CTRL_SHL_STALL:
begin
end
CTRL_LOOP:
begin
end
default:
begin
end
endcase
end
endmodule // residue
//======================================================================
// EOF residue.v
//======================================================================
