[System verilog ] Accessing an array with range varying along with upper and lower limits and the width of the array

SystemVerilog
,
1

Hi

Want to access the array with different width sizes along with different upper and lower limits .

The Sample code is as follows (Ignore the begin/end syntax )

foreach(fields[i]) begin
         if(fields[i].get_name().substr(0,7) != "reserved")    begin
          const int lsb_i= fields[i].get_lsb_pos() ;
          const int msb_i = fields[i].get_lsb_pos() + fields[i].get_n_bits()-1;
          int size_of = msb_i - lsb_i + 1;
          if((r_data[msb_i -:size_of] ) ==( m_data[msb_i -:size_of] ) ) 
    begin
         `uvm_info(get_type_name(),$sformatf("Matching data for Reg %s with fields[i] %s read data = %0h and mirror_data = %0h @ Addr=%0h", regs[i].get_name(),                           fields[i].get_name() ,r_data ,m_data, regs[i].get_address()), UVM_MEDIUM);
    end
           else
          `uvm_error(get_name(),$sformatf("MIsMatching data for Reg %s with fields[i] %s read data = %0h and mirror_data = %0h @ Addr=%0h", regs[i].get_name(),                         fields[i].get_name() ,r_data ,m_data, regs[i].get_address()));  
         end

The Problem is with the BLOCK code ,

The array doesnt suppoort the indices for range being variable .

I get an error as follows :

if((r_data[msb_i -:size_of] ) ==( m_data[msb_i -:size_of] ) ) 
                                   |
xmvlog: *E,NOTPAR (/vobs/asic/hawkowl/src/jor/src/jor_top_sec/tb/lib/env/er_jor_insec_reg_seq_lib.svh,220|35): Illegal operand for constant expression [4(IEEE)].
          if((r_data[msb_i -:size_of] ) ==( m_data[msb_i -:size_of] ) ) 
                                                                 |
xmvlog: *E,NOTPAR (/vobs/asic/hawkowl/src/jor/src/jor_top_sec/tb/lib/env/er_jor_insec_reg_seq_lib.svh,220|65): Illegal operand for constant expression [4(IEEE)].

So please help me solving this issue .

Thanks in advance

2

In reply to rajivdesh:

Verilog does not allow integral operands having widths dynamically sized; their widths must be constant expressions computed at compile time. A const variable cannot be used in a constant expression because its value gets computed at runtime. In this case, the variables get initialized in each iteration of the foreach loop.

You can either write a for-loop comparing each bit

if(fields[i].get_name().substr(0,7) != "reserved")    begin
          int lsb_i= fields[i].get_lsb_pos() ;
          int msb_p = fields[i].get_lsb_pos() + fields[i].get_n_bits();
          bit match = 1;
          for(int idx=lsb_i; idx < msb_p; idx++)
            if( r_data[idx] != m_data[idx] ) begin
                match = 0; break;
            end
          if (match)
            `uvm_info(get_type_name(),$sformatf("Matching data for Reg %s with fields[i] %s read data = %0h and mirror_data = %0h @ Addr=%0h", regs[i].get_name(),                           fields[i].get_name() ,r_data ,m_data, regs[i].get_address()), UVM_MEDIUM)
           else
             `uvm_error(get_name(),$sformatf("MIsMatching data for Reg %s with fields[i] %s read data = %0h and mirror_data = %0h @ Addr=%0h", regs[i].get_name(),                         fields[i].get_name() ,r_data ,m_data, regs[i].get_address()))
end

Or you can create a mask

if(fields[i].get_name().substr(0,7) != "reserved")    begin
          int lsb_i  = fields[i].get_lsb_pos() ;
          int size_i = fields[i].get_n_bits();
          bit [$bits(r_data)-1:0] mask = 3(2'b1 << size_i) -1) << lab_i;
          if (r_data && mask == m_data && mask)
            `uvm_info(get_type_name(),$sformatf("Matching data for Reg %s with fields[i] %s read data = %0h and mirror_data = %0h @ Addr=%0h", regs[i].get_name(),                           fields[i].get_name() ,r_data ,m_data, regs[i].get_address()), UVM_MEDIUM)
           else
             `uvm_error(get_name(),$sformatf("MIsMatching data for Reg %s with fields[i] %s read data = %0h and mirror_data = %0h @ Addr=%0h", regs[i].get_name(),                         fields[i].get_name() ,r_data ,m_data, regs[i].get_address()))
end

All untested :)