crc_32.v

crc校验功能

module crc_32 (clk, reset_n, data_in, crc_out);


input clk;
input reset_n;
input [15:0] data_in;


output [31:0] crc_out;

reg   [15:0]data_in_reg;
wire  [31:0] crc_out;

wire [31:0] previous_remainder;
wire [31:0] crc_result;

reg [31:0] crc_result_reg;

always @ (posedge clk or negedge reset_n)
begin
  if (~reset_n) 
    data_in_reg = 16'h0000;
  else 
    data_in_reg = data_in;
 end

assign previous_remainder=crc_result_reg;


assign  crc_result[0] = data_in_reg[0] ^ previous_remainder[28] ^ previous_remainder[22] ^ 
                   previous_remainder[25] ^ previous_remainder[26] ^ 
                   previous_remainder[16];

assign  crc_result[1] = data_in_reg[1] ^ previous_remainder[29] ^ previous_remainder[23] ^ 
                   previous_remainder[27] ^ previous_remainder[17] ^ previous_remainder[28] ^ 
                   previous_remainder[22] ^ previous_remainder[25] ^  
                   previous_remainder[16]; 

 assign crc_result[2] = data_in_reg[2] ^ previous_remainder[30] ^ previous_remainder[24] ^ 
                   previous_remainder[18] ^ previous_remainder[29] ^ previous_remainder[23] ^ 
                   previous_remainder[17] ^ previous_remainder[22] ^ previous_remainder[25] ^ 
                   previous_remainder[16];

assign  crc_result[3] = data_in_reg[3] ^ previous_remainder[31] ^ previous_remainder[25] ^ 
                   previous_remainder[19] ^ previous_remainder[30] ^ previous_remainder[24] ^ 
                   previous_remainder[18] ^ previous_remainder[23] ^ previous_remainder[26] ^ 
                   previous_remainder[17];

assign  crc_result[4] = data_in_reg[4] ^  previous_remainder[20] ^ 
                   previous_remainder[31] ^ previous_remainder[19] ^ previous_remainder[24] ^ 
                   previous_remainder[27] ^ previous_remainder[18] ^ previous_remainder[28] ^ 
                   previous_remainder[22] ^ previous_remainder[16];

assign  crc_result[5] = data_in_reg[5] ^ previous_remainder[21] ^ previous_remainder[29] ^ 
                   previous_remainder[20] ^ previous_remainder[19] ^ previous_remainder[23] ^ 
                   previous_remainder[17] ^ previous_remainder[22] ^ previous_remainder[26] ^ 
                   previous_remainder[16];

assign  crc_result[6] = data_in_reg[6] ^ previous_remainder[22] ^ previous_remainder[30] ^ 
                   previous_remainder[21] ^ previous_remainder[20] ^ previous_remainder[24] ^ 
                   previous_remainder[18] ^ previous_remainder[23] ^ previous_remainder[27] ^ 
                   previous_remainder[17];

assign  crc_result[7] = data_in_reg[7] ^ previous_remainder[23] ^ previous_remainder[31] ^ 
                   previous_remainder[21] ^ previous_remainder[19] ^ previous_remainder[24] ^ 
                   previous_remainder[18] ^ previous_remainder[26] ^  
                   previous_remainder[16];

assign crc_result[8] = data_in_reg[8] ^ previous_remainder[24] ^ previous_remainder[28] ^ 
                   previous_remainder[26] ^ previous_remainder[20] ^ previous_remainder[19] ^ 
                   previous_remainder[27] ^ previous_remainder[17] ^  
                   previous_remainder[16];

assign  crc_result[9] = data_in_reg[9] ^ previous_remainder[25] ^ previous_remainder[29] ^ 
                   previous_remainder[27] ^ previous_remainder[21] ^ previous_remainder[20] ^ 
                   previous_remainder[28] ^ previous_remainder[18] ^ previous_remainder[17];

assign crc_result[10]= data_in_reg[10] ^ previous_remainder[25] ^ previous_remainder[21] ^ 
                   previous_remainder[29] ^ previous_remainder[19] ^ previous_remainder[18] ^ 
                   previous_remainder[16]^previous_remainder[30];


assign crc_result[11]= data_in_reg[11] ^ previous_remainder[20] ^ previous_remainder[31] ^ 
                   previous_remainder[25] ^ previous_remainder[19] ^ previous_remainder[17] ^ 
                   previous_remainder[28] ^ previous_remainder[16]^previous_remainder[30];

assign  crc_result[12]= data_in_reg[12] ^ previous_remainder[31]  ^ 
                   previous_remainder[29] ^ previous_remainder[28] ^ previous_remainder[21] ^ 
                   previous_remainder[20] ^ previous_remainder[18] ^ previous_remainder[17] ^ 
                   previous_remainder[22] ^ previous_remainder[25] ^ previous_remainder[16];    

assign  crc_result[14 : 13]= data_in_reg[14 : 13] ^ previous_remainder[31 : 30] ^ 
                             previous_remainder[30 : 29] ^ previous_remainder[23 : 22] ^ 
                             previous_remainder[22 : 21] ^ previous_remainder[20 : 19] ^ 
                             previous_remainder[19 : 18] ^ previous_remainder[24 : 23] ^ 
                             previous_remainder[27 : 26] ^ previous_remainder[18 : 17];

assign  crc_result[15]= data_in_reg[15] ^ previous_remainder[31] ^ previous_remainder[24] ^ 
                   previous_remainder[23] ^ previous_remainder[21] ^ previous_remainder[20] ^ 
                   previous_remainder[25] ^ previous_remainder[28] ^ previous_remainder[19];

assign  crc_result[16]= previous_remainder[0] ^ previous_remainder[24] ^ previous_remainder[28] ^ 
                   previous_remainder[21] ^ previous_remainder[20] ^ previous_remainder[16] ^ 
                   previous_remainder[29]; 
   
 assign crc_result[18 : 17]= previous_remainder[2 : 1] ^ previous_remainder[26 : 25] ^ 
                             previous_remainder[30 : 29] ^ previous_remainder[23 : 22] ^ 
                             previous_remainder[22 : 21] ^ previous_remainder[18 : 17] ^ 
                             previous_remainder[31 : 30];

assign  crc_result[19]= previous_remainder[3] ^ previous_remainder[27] ^ previous_remainder[31] ^ 
                   previous_remainder[24] ^ previous_remainder[23] ^ previous_remainder[19];     
  
assign  crc_result[21 : 20]= previous_remainder[5 : 4] ^ previous_remainder[29 : 28] ^ 
                             previous_remainder[26 : 25] ^ previous_remainder[25 : 24] ^ 
                             previous_remainder[21 : 20];

assign  crc_result[22]= previous_remainder[6] ^ previous_remainder[28] ^ previous_remainder[27] ^ 
                   previous_remainder[25] ^ previous_remainder[16]^previous_remainder[30];

assign crc_result[23]= previous_remainder[7] ^ previous_remainder[31] ^ previous_remainder[29] ^ 
                   previous_remainder[17] ^ previous_remainder[22] ^ previous_remainder[25] ^ 
                   previous_remainder[16] ;

assign  crc_result[25 : 24]= previous_remainder[9 : 8] ^ previous_remainder[31 : 30] ^
                             previous_remainder[24 : 23] ^ previous_remainder[19 : 18] ^ 
                             previous_remainder[27 : 26] ^ previous_remainder[18 : 17];

assign  crc_result[26]= previous_remainder[10] ^ previous_remainder[20] ^ previous_remainder[19] ^ 
                   previous_remainder[22] ^ previous_remainder[26]  ^
                   previous_remainder[16];     

assign  crc_result[31 : 27]= previous_remainder[15 : 11] ^ previous_remainder[31 : 27] ^ 
                             previous_remainder[25 : 21] ^ previous_remainder[24 : 20] ^ 
                             previous_remainder[27 : 23] ^ previous_remainder[21 : 17];


always @ (posedge clk or negedge reset_n)
 begin
  if (~reset_n)
    crc_result_reg = 32'h00000000;
  else
     crc_result_reg = crc_result;
end

assign crc_out=crc_result_reg;

endmodule