class spi_trans; 

  //Properties for Randomizing the MOSI 
  rand bit	  cmd;
  rand bit	  s;
  rand bit[24:0]  addr;
  rand bit[ 4:0]  op;
  rand bit[31:0]  data[];

  //Properties for Randomizing the pkt_sent process
  rand int		interval;
  rand int		half_sclk;


  constraint cstr {
    (s==1'b0 && data.size()==1) || (s==1'b1 && data.size()==16);
    interval    <=  1000;
    interval    >=  0;
    half_sclk   <=  32;
    half_sclk   >=  4;
    (addr	>=  25'h000_0000 &&
     addr	<=  25'h000_0033 &&
     s		==  1'b0	)   ||
    (addr	>=  25'h010_0000 &&
     addr	<=  25'h010_001F &&
     s		==  1'b0	)   ||
    (addr	>=  25'h010_0040 &&
     addr	<=  25'h010_00A7 &&
     s		==  1'b0	)   ||
    (addr	>=  25'h010_0040 &&
     addr	<=  25'h010_0067 &&
     s		==  1'b1	)   ||
    (addr	>=  25'h020_0000 &&
     addr	<=  25'h020_001F &&
     s		==  1'b0	)   ||
    (addr	>=  25'h020_0098 &&
     addr	<=  25'h020_00A3 &&
     s		==  1'b0	)   ||
    (addr	>=  25'h020_0100 &&
     addr	<=  25'h020_0123 &&
     s		==  1'b0	)   ||
    (addr	>=  25'h020_0128 &&
     addr	<=  25'h020_014F &&
     s		==  1'b1	)   ||
    (addr	>=  25'h020_0128 &&
     addr	<=  25'h020_018F &&
     s		==  1'b0	);
    (addr	<   25'h000_0020)   ||
    (addr	>   25'h000_0023)   ||
    (data[0]	<=  500);
  }

  function new();
  endfunction

  extern function bit  compare(spi_trans rhs_);
  extern function void print();
  extern function void unpack(ref bit stream[$]);

endclass : spi_trans 



function bit spi_trans::compare(spi_trans rhs_);
  bit 		result=1'b1;
  int		i=0;

  result = ((this.cmd 	== rhs_.cmd) &&
	    (this.s 	== rhs_.s) &&
	    (this.addr 	== rhs_.addr) &&
	    (this.op 	== rhs_.op));

  if(this.data.size() != rhs_.data.size()) begin
    $display("data_sizes are different");
    result = 1'b0;
  end
  else 
    for(i=0;i<this.data.size();i++)begin
    	if(this.data[i] != rhs_.data[i])
	  result = 1'b0;
    end

  return result;
endfunction : compare


function void spi_trans::print();
  int i=0;
  $display("cmd:",this.cmd);
  $display("s:",this.s);
  $display("addr:",this.addr);
  $display("op:",this.op);
  for(i=0;i<this.data.size();i++)begin
    $display("data[%d]='h%h=%d",i,data[i],data[i]);
  end
endfunction : print


function void spi_trans::unpack(ref bit stream[$]);
  int i=0,j=0;

  stream[0]=cmd;
  
  stream[1]=s;

  for(i=0;i<25;i++)
    stream[i+2] = addr[24-i];//Q:If the addr is 1234, is "1" occurs firstly or "4" does?

  for(i=0;i<5;i++)
    stream[i+27]= op[4-i];
  
  for(i=0;i<this.data.size();i++)begin
    //$display("i=%2d,datai=%b",i,data[i]);
    for(j=0;j<32;j++)begin
      stream[32+i*32+j]=data[i][31-j];
      //$display("i=%2d,j=%2d,streamij=%b",i,j,stream[32+i*32+j]);
    end
  end

endfunction