Subversion Repositories bch_configurable

///-----------------------------------------

///introduce:

///bch error position search in decoder

///author:jiml

///record:

///2015.1.31    initial

///-----------------------------------------

`timescale 1ns/100ps

module test_chian_search

#(

parameter C_PRIMPOLY_ORDER = 14,              //order of eigenpolynomial

parameter C_COEF_NUM = 43,                    //correct threshold

parameter C_TOTALBIT_NUM = 8832,              //total bit length include original and correct bits

parameter C_THREAD_NUM = 8,                   //parallel search thread

parameter C_PRIMPOLY = 15'h4443               //eigenpolynomial

)

(

input                                                         I_clk       ,

input                                                         I_rst       ,

input      [C_PRIMPOLY_ORDER*C_COEF_NUM-1+C_PRIMPOLY_ORDER:0] I_coef      ,  //error position polynomial

input                                                         I_coef_v    ,  //error position polynomial available

output reg [C_THREAD_NUM-1:0]                                 O_data      ,  //check data

output reg                                                    O_data_v    ,  //check data available

output reg                                                    O_data_sof  ,  //check data frame start

output reg                                                    O_data_eof     //check data frame end

);

//--------------------------------------------

//parameter and variable

//--------------------------------------------

localparam C_SEARCH_START = 2**C_PRIMPOLY_ORDER - 1 - C_TOTALBIT_NUM;

localparam C_CNT_LIMIT = (C_TOTALBIT_NUM-1)/C_THREAD_NUM;

localparam C_CNT_LIMIT_WIDTH = GETASIZE(C_CNT_LIMIT);

reg S_search_v = 0;

reg [C_PRIMPOLY_ORDER-1:0] S_const = 0;

reg S_search_v_d = 0;

reg S_search_v_2d = 0;

reg S_search_v_3d = 0;

reg [C_CNT_LIMIT_WIDTH:0] S_search_cnt = 0;

reg [C_PRIMPOLY_ORDER*C_COEF_NUM-1:0] S_var [C_THREAD_NUM-1:0];

reg [C_PRIMPOLY_ORDER*C_COEF_NUM-1+C_PRIMPOLY_ORDER:0] S_var_xor [C_THREAD_NUM-1:0];

reg [C_PRIMPOLY_ORDER-1:0] S_var_xor_result [C_THREAD_NUM-1:0];

reg [C_THREAD_NUM-1:0] S_err_id = 0;

wire [C_PRIMPOLY_ORDER*C_COEF_NUM-1:0] S_coef1;

wire integer S_coef2 [C_THREAD_NUM-1:0];

//--------------------------------------------

//function

//--------------------------------------------

//element multiplication in Galois Field

function [C_PRIMPOLY_ORDER-1:0] F_var_upgrade;

input [C_PRIMPOLY_ORDER-1:0] S_mult;

input integer S_times;

integer i;

reg [C_PRIMPOLY_ORDER-1:0] S_temp;

reg [C_PRIMPOLY_ORDER-1:0] S_temp2;

reg S_temp_upp;

begin

        S_temp = S_mult;

        for(i=0;i<S_times;i=i+1)

        begin

                S_temp_upp = S_temp[C_PRIMPOLY_ORDER-1];

                S_temp2 = S_temp<<1;

                S_temp = S_temp2 ^ (C_PRIMPOLY[C_PRIMPOLY_ORDER-1:0] & {C_PRIMPOLY_ORDER{S_temp_upp}});

        end

        F_var_upgrade = S_temp;

end

endfunction

//width calculation

function integer GETASIZE;

input integer a;

integer i;

begin

    for(i=1;(2**i)<a;i=i+1)

      begin

      end

    GETASIZE = i;

end

endfunction

///-------------------------------

///search

///-------------------------------

always @(posedge I_clk)

begin

    if(I_rst)

            S_search_v <= 'd0;

        else if(I_coef_v)

            S_search_v <= 'd1;

        else if(S_search_cnt == C_CNT_LIMIT)

            S_search_v <= 'd0;

end

always @(posedge I_clk)

begin

    if(S_search_v)

            S_search_cnt <= S_search_cnt + 'd1;

        else

            S_search_cnt <= 'd0;

end

always @(posedge I_clk)

begin

        S_search_v_d <= S_search_v;

        S_search_v_2d <= S_search_v_d;

        S_search_v_3d <= S_search_v_2d;

end

always @(posedge I_clk)

begin

    if(I_coef_v)

            S_const <= I_coef[C_PRIMPOLY_ORDER-1:0];

end

assign S_coef1 = I_coef_v ? I_coef[C_PRIMPOLY_ORDER+:C_PRIMPOLY_ORDER*C_COEF_NUM] : S_var[C_THREAD_NUM-1];

genvar S_k;

integer k,kk;

generate

for(S_k=0;S_k<C_THREAD_NUM;S_k=S_k+1)                   //parallel search

begin:process

assign S_coef2[S_k] = I_coef_v ? C_SEARCH_START : (S_k+1);

always @(posedge I_clk)

begin

    for(k=0;k<C_COEF_NUM;k=k+1)

                S_var[S_k][C_PRIMPOLY_ORDER*k+:C_PRIMPOLY_ORDER] <= F_var_upgrade(S_coef1[C_PRIMPOLY_ORDER*k+:C_PRIMPOLY_ORDER],S_coef2[S_k]*(k+1));

end

always @(*)

begin

    S_var_xor[S_k][0+:C_PRIMPOLY_ORDER] = S_const;

end

always @(*)

begin

        for(kk=0;kk<C_COEF_NUM;kk=kk+1)

        S_var_xor[S_k][C_PRIMPOLY_ORDER*(kk+1)+:C_PRIMPOLY_ORDER] = I_coef_v ? 'd0 : (S_var_xor[S_k][C_PRIMPOLY_ORDER*(kk)+:C_PRIMPOLY_ORDER] ^ S_var[S_k][C_PRIMPOLY_ORDER*kk+:C_PRIMPOLY_ORDER]);

end

always @(posedge I_clk)

begin

    S_var_xor_result[S_k] <= S_var_xor[S_k][C_PRIMPOLY_ORDER*C_COEF_NUM+:C_PRIMPOLY_ORDER];

end

always @(posedge I_clk)

begin

    S_err_id[S_k] <= (S_var_xor_result[S_k] == 'd0);   //zero means error position

end

end

endgenerate

//-------------------------------------------

//check data output

//-------------------------------------------

always @(posedge I_clk)

begin

    O_data <= S_err_id;

        O_data_v <= S_search_v_3d;

end

always @(posedge I_clk)

begin

    O_data_sof <= S_search_v_3d && (!O_data_v);

        O_data_eof <= (!S_search_v_2d) && S_search_v_3d;

end

endmodule