chien-search.v

encode.v The encoder syndrome.v Syndrome generator in decoder berlekamp.v Berlekamp algorithm in

// -------------------------------------------------------------------------
//Chien-Forney search circuit for Reed-Solomon decoder
//Copyright (C) Tue Apr  2 16:43:02 2002
//by Ming-Han Lei([e-mail])
//
//This program is free software; you can redistribute it and/or
//modify it under the terms of the GNU Lesser General Public License
//as published by the Free Software Foundation; either version 2
//of the License, or (at your option) any later version.
//
//This program is distributed in the hope that it will be useful,
//but WITHOUT ANY WARRANTY; without even the implied warranty of
//MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//GNU Lesser General Public License for more details.
//
//You should have received a copy of the GNU Lesser General Public License
//along with this program; if not, write to the Free Software
//Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
// --------------------------------------------------------------------------

module rsdec_chien_scale0 (y, x);
	input [7:0] x;
	output [7:0] y;
	reg [7:0] y;

	always @ (x)
	begin
		y[0] = x[0];
		y[1] = x[1];
		y[2] = x[2];
		y[3] = x[3];
		y[4] = x[4];
		y[5] = x[5];
		y[6] = x[6];
		y[7] = x[7];
	end
endmodule

module rsdec_chien_scale1 (y, x);
	input [7:0] x;
	output [7:0] y;
	reg [7:0] y;

	always @ (x)
	begin
		y[0] = x[7];
		y[1] = x[0];
		y[2] = x[1] ^ x[7];
		y[3] = x[2] ^ x[7];
		y[4] = x[3] ^ x[7];
		y[5] = x[4];
		y[6] = x[5];
		y[7] = x[6];
	end
endmodule

module rsdec_chien_scale2 (y, x);
	input [7:0] x;
	output [7:0] y;
	reg [7:0] y;

	always @ (x)
	begin
		y[0] = x[6];
		y[1] = x[7];
		y[2] = x[0] ^ x[6];
		y[3] = x[1] ^ x[6] ^ x[7];
		y[4] = x[2] ^ x[6] ^ x[7];
		y[5] = x[3] ^ x[7];
		y[6] = x[4];
		y[7] = x[5];
	end
endmodule

module rsdec_chien_scale3 (y, x);
	input [7:0] x;
	output [7:0] y;
	reg [7:0] y;

	always @ (x)
	begin
		y[0] = x[5];
		y[1] = x[6];
		y[2] = x[5] ^ x[7];
		y[3] = x[0] ^ x[5] ^ x[6];
		y[4] = x[1] ^ x[5] ^ x[6] ^ x[7];
		y[5] = x[2] ^ x[6] ^ x[7];
		y[6] = x[3] ^ x[7];
		y[7] = x[4];
	end
endmodule

module rsdec_chien_scale4 (y, x);
	input [7:0] x;
	output [7:0] y;
	reg [7:0] y;

	always @ (x)
	begin
		y[0] = x[4];
		y[1] = x[5];
		y[2] = x[4] ^ x[6];
		y[3] = x[4] ^ x[5] ^ x[7];
		y[4] = x[0] ^ x[4] ^ x[5] ^ x[6];
		y[5] = x[1] ^ x[5] ^ x[6] ^ x[7];
		y[6] = x[2] ^ x[6] ^ x[7];
		y[7] = x[3] ^ x[7];
	end
endmodule

module rsdec_chien_scale5 (y, x);
	input [7:0] x;
	output [7:0] y;
	reg [7:0] y;

	always @ (x)
	begin
		y[0] = x[3] ^ x[7];
		y[1] = x[4];
		y[2] = x[3] ^ x[5] ^ x[7];
		y[3] = x[3] ^ x[4] ^ x[6] ^ x[7];
		y[4] = x[3] ^ x[4] ^ x[5];
		y[5] = x[0] ^ x[4] ^ x[5] ^ x[6];
		y[6] = x[1] ^ x[5] ^ x[6] ^ x[7];
		y[7] = x[2] ^ x[6] ^ x[7];
	end
endmodule

module rsdec_chien_scale6 (y, x);
	input [7:0] x;
	output [7:0] y;
	reg [7:0] y;

	always @ (x)
	begin
		y[0] = x[2] ^ x[6] ^ x[7];
		y[1] = x[3] ^ x[7];
		y[2] = x[2] ^ x[4] ^ x[6] ^ x[7];
		y[3] = x[2] ^ x[3] ^ x[5] ^ x[6];
		y[4] = x[2] ^ x[3] ^ x[4];
		y[5] = x[3] ^ x[4] ^ x[5];
		y[6] = x[0] ^ x[4] ^ x[5] ^ x[6];
		y[7] = x[1] ^ x[5] ^ x[6] ^ x[7];
	end
endmodule

module rsdec_chien_scale7 (y, x);
	input [7:0] x;
	output [7:0] y;
	reg [7:0] y;

	always @ (x)
	begin
		y[0] = x[1] ^ x[5] ^ x[6] ^ x[7];
		y[1] = x[2] ^ x[6] ^ x[7];
		y[2] = x[1] ^ x[3] ^ x[5] ^ x[6];
		y[3] = x[1] ^ x[2] ^ x[4] ^ x[5];
		y[4] = x[1] ^ x[2] ^ x[3] ^ x[7];
		y[5] = x[2] ^ x[3] ^ x[4];
		y[6] = x[3] ^ x[4] ^ x[5];
		y[7] = x[0] ^ x[4] ^ x[5] ^ x[6];
	end
endmodule

module rsdec_chien (error, alpha, lambda, omega, even, D, search, load, shorten, clk, clrn);
	input clk, clrn, load, search, shorten;
	input [7:0] D;
	input [7:0] lambda;
	input [7:0] omega;
	output [7:0] even, error;
	output [7:0] alpha;
	reg [7:0] even, error;
	reg [7:0] alpha;

	wire [7:0] scale0;
	wire [7:0] scale1;
	wire [7:0] scale2;
	wire [7:0] scale3;
	wire [7:0] scale4;
	wire [7:0] scale5;
	wire [7:0] scale6;
	wire [7:0] scale7;
	wire [7:0] scale8;
	wire [7:0] scale9;
	wire [7:0] scale10;
	wire [7:0] scale11;
	wire [7:0] scale12;
	wire [7:0] scale13;
	wire [7:0] scale14;
	wire [7:0] scale15;
	reg [7:0] data0;
	reg [7:0] data1;
	reg [7:0] data2;
	reg [7:0] data3;
	reg [7:0] data4;
	reg [7:0] data5;
	reg [7:0] data6;
	reg [7:0] data7;
	reg [7:0] a0;
	reg [7:0] a1;
	reg [7:0] a2;
	reg [7:0] a3;
	reg [7:0] a4;
	reg [7:0] a5;
	reg [7:0] a6;
	reg [7:0] a7;
	reg [7:0] l0;
	reg [7:0] l1;
	reg [7:0] l2;
	reg [7:0] l3;
	reg [7:0] l4;
	reg [7:0] l5;
	reg [7:0] l6;
	reg [7:0] l7;
	reg [7:0] o0;
	reg [7:0] o1;
	reg [7:0] o2;
	reg [7:0] o3;
	reg [7:0] o4;
	reg [7:0] o5;
	reg [7:0] o6;
	reg [7:0] o7;
	reg [7:0] odd, numerator;
	wire [7:0] tmp;
	integer j;

	rsdec_chien_scale0 x0 (scale0, data0);
	rsdec_chien_scale1 x1 (scale1, data1);
	rsdec_chien_scale2 x2 (scale2, data2);
	rsdec_chien_scale3 x3 (scale3, data3);
	rsdec_chien_scale4 x4 (scale4, data4);
	rsdec_chien_scale5 x5 (scale5, data5);
	rsdec_chien_scale6 x6 (scale6, data6);
	rsdec_chien_scale7 x7 (scale7, data7);
	rsdec_chien_scale0 x8 (scale8, o0);
	rsdec_chien_scale1 x9 (scale9, o1);
	rsdec_chien_scale2 x10 (scale10, o2);
	rsdec_chien_scale3 x11 (scale11, o3);
	rsdec_chien_scale4 x12 (scale12, o4);
	rsdec_chien_scale5 x13 (scale13, o5);
	rsdec_chien_scale6 x14 (scale14, o6);
	rsdec_chien_scale7 x15 (scale15, o7);

	always @ (shorten or a0 or l0)
		if (shorten) data0 = a0;
		else data0 = l0;

	always @ (shorten or a1 or l1)
		if (shorten) data1 = a1;
		else data1 = l1;

	always @ (shorten or a2 or l2)
		if (shorten) data2 = a2;
		else data2 = l2;

	always @ (shorten or a3 or l3)
		if (shorten) data3 = a3;
		else data3 = l3;

	always @ (shorten or a4 or l4)
		if (shorten) data4 = a4;
		else data4 = l4;

	always @ (shorten or a5 or l5)
		if (shorten) data5 = a5;
		else data5 = l5;

	always @ (shorten or a6 or l6)
		if (shorten) data6 = a6;
		else data6 = l6;

	always @ (shorten or a7 or l7)
		if (shorten) data7 = a7;
		else data7 = l7;

	always @ (posedge clk or negedge clrn)
	begin
		if (~clrn)
		begin
			l0 <= 0;
			l1 <= 0;
			l2 <= 0;
			l3 <= 0;
			l4 <= 0;
			l5 <= 0;
			l6 <= 0;
			l7 <= 0;
			o0 <= 0;
			o1 <= 0;
			o2 <= 0;
			o3 <= 0;
			o4 <= 0;
			o5 <= 0;
			o6 <= 0;
			o7 <= 0;
			a0 <= 1;
			a1 <= 1;
			a2 <= 1;
			a3 <= 1;
			a4 <= 1;
			a5 <= 1;
			a6 <= 1;
			a7 <= 1;
		end
		else if (shorten)
		begin
			a0 <= scale0;
			a1 <= scale1;
			a2 <= scale2;
			a3 <= scale3;
			a4 <= scale4;
			a5 <= scale5;
			a6 <= scale6;
			a7 <= scale7;
		end
		else if (search)
		begin
			l0 <= scale0;
			l1 <= scale1;
			l2 <= scale2;
			l3 <= scale3;
			l4 <= scale4;
			l5 <= scale5;
			l6 <= scale6;
			l7 <= scale7;
			o0 <= scale8;
			o1 <= scale9;
			o2 <= scale10;
			o3 <= scale11;
			o4 <= scale12;
			o5 <= scale13;
			o6 <= scale14;
			o7 <= scale15;
		end
		else if (load)
		begin
			l0 <= lambda;
			l1 <= l0;
			l2 <= l1;
			l3 <= l2;
			l4 <= l3;
			l5 <= l4;
			l6 <= l5;
			l7 <= l6;
			o0 <= omega;
			o1 <= o0;
			o2 <= o1;
			o3 <= o2;
			o4 <= o3;
			o5 <= o4;
			o6 <= o5;
			o7 <= o6;
			a0 <= a7;
			a1 <= a0;
			a2 <= a1;
			a3 <= a2;
			a4 <= a3;
			a5 <= a4;
			a6 <= a5;
			a7 <= a6;
		end
	end

	always @ (l0 or l2 or l4 or l6)
		even = l0 ^ l2 ^ l4 ^ l6;

	always @ (l1 or l3 or l5 or l7)
		odd = l1 ^ l3 ^ l5 ^ l7;

	always @ (o0 or o1 or o2 or o3 or o4 or o5 or o6 or o7)
		numerator = o0 ^ o1 ^ o2 ^ o3 ^ o4 ^ o5 ^ o6 ^ o7;

	multiply m0 (tmp, numerator, D);

	always @ (even or odd or tmp)
		if (even == odd) error = tmp;
		else error = 0;

	always @ (a7) alpha = a7;

endmodule