issue regarding 32 bit crc implementation in transaction class of ethernet packets in uvm methodology

[samrat patel]

Hello Friends,

I am samrat Patel from ahmedabad
Currently i am working on a project of ethernet packet using uvm methodology.In project i have to implement a 32 bit crc logic in transaction class . i have seen some material on crc but for 32 bit crc i am not getting properly that how to do XOR calculation between 32 bit crc and 8 bit data.so any one can elaboreate it and help me for this that how can i do crc implemenation?

If u know reply me asap

email id:samrat150590@gmail.com
contact no: 09016464567

Thanks,

Regards,
Samrat Patel

 

->Following is my transaction class

 

//ethernet transaction class declaration 

class eth_transaction extends uvm_sequence_item;

 

//ethernet packet field ranomization 

  rand bit [55:0] preamble;

  rand bit [7:0] sfd;

  rand bit [47:0] dst_addr;

  rand bit [47:0] src_addr;

  rand bit [15:0] data_len; // this length can accomodate MAXIMUM length of 1500

  rand bit [7:0] payload [];

  rand bit [31:0] crc;    

 

  rand int unsigned transmit_delay;//transmit delay between transfers

  

  constraint c_delay {transmit_delay==10;}//constraint on transmit delay-constraint as per need

 

//constraint on specific field

 

constraint preamble_con{

                        preamble=={7{8'haa}};

                        }

  

constraint sfd_con{

                   sfd== 8'hab;

                   }

    

constraint data_len_con{

                        data_len inside {[46:1500]};

                        solve data_len before payload;

                       }

 

constraint payload_con{

                        payload.size==data_len;

                       }

 

 

 

//macro registraton

`uvm_object_utils_begin(eth_transaction)

  

  `uvm_field_int(preamble,UVM_ALL_ON|UVM_NOPACK)

  `uvm_field_int(sfd,UVM_ALL_ON|UVM_NOPACK)

  `uvm_field_int(dst_addr,UVM_ALL_ON|UVM_NOPACK)

  `uvm_field_int(src_addr,UVM_ALL_ON|UVM_NOPACK)

  `uvm_field_int(data_len,UVM_ALL_ON|UVM_NOPACK)

  `uvm_field_array_int(payload,UVM_ALL_ON|UVM_NOPACK)

  `uvm_field_int(crc,UVM_ALL_ON|UVM_NOPACK)

  `uvm_field_int(transmit_delay,UVM_DEFAULT|UVM_NOCOMPARE|UVM_NOPACK)

 

`uvm_object_utils_end

 

//constructor

function new(string name = "eth_transaction");

  super.new(name);

endfunction

  

//display method  

function void display(string strng);

 

  $display("\n@time=%0g\tpacket displaying from %s",$time,strng);

  $display("||==============||======||============||============||============||===============||========||");

  $display("|| preamble     || sfd  || dst_addr   || src_addr   ||   data_Len ||   payload_Len ||  crc   ||");

  $display("||--------------||------||------------||------------||------------||---------------||--------||");

  $display("||%h||  %h  ||%h||%h||    %4d    ||     %6d    ||%h||",preamble,

                                                                   sfd,

                                                                   dst_addr,

                                                                   src_addr,

                                                                   data_len,

                                                                   payload.size,

                                                                   crc);

  $display("||==============||======||============||============||============||===============||========||");

  $display("\n");

 

endfunction

 

//pack all bits of ethernet packet field

function void do_pack(uvm_packer packer);

  

  super.do_pack(packer); // pack super's properties

  

  packer.pack_field_int(preamble,$bits(preamble));

  packer.pack_field_int(sfd,$bits(sfd));

  packer.pack_field_int(dst_addr,$bits(dst_addr));

  packer.pack_field_int(src_addr,$bits(src_addr));

  packer.pack_field_int(data_len,$bits(data_len));

  foreach(payload)

  packer.pack_field_int(payload,8);

  packer.pack_field_int(crc,$bits(crc));

  

endfunction : do_pack

    

//unpack all bits of ethernet packet field

function void do_unpack(uvm_packer packer);

  

  super.do_unpack(packer); // unpack super's properties

    

  preamble = packer.unpack_field_int($bits(preamble));

  sfd = packer.unpack_field_int($bits(sfd));

  dst_addr = packer.unpack_field_int($bits(dst_addr));

  src_addr = packer.unpack_field_int($bits(src_addr));

  data_len = packer.unpack_field_int($bits(data_len));

  payload.delete();

  payload = new[data_len];

  foreach(payload)

  payload = packer.unpack_field_int(8);

  crc = packer.unpack_field_int($bits(crc));

  

endfunction : do_unpack

 

//do_compare method -to compare specific field

function bit do_compare(uvm_object rhs,uvm_comparer comparer);

    eth_transaction rhs_;

    bit status=1;

    $cast(rhs_,rhs);

    status &= (preamble == rhs_.preamble);

    status &= (sfd == rhs_.sfd);

    status &= (dst_addr == rhs_.dst_addr);

    status &= (src_addr == rhs_.src_addr);

    status &= (data_len == rhs_.data_len);

    status &= (payload == rhs_.payload);

    status &= (crc == rhs_.crc);

    return status;

endfunction

 

endclass: eth_transaction