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Package, and record array in VHDL using free simulator GHDL.

1. The following short and simple VHDL tip shows the usage of a record array in VHDL. The small case is tested via the free VHDL simulator: GHDL.


2. The test case is made of two VHDL files: a small package and the test-bench. Part of the package is shown below:

The package my_package is

type enum_size is (ZERO,EIGHT,SIXTEEN, THIRTY_TWO);
type enum_direction is (RW, RD);

  type reg is record
    direction: enum_direction;
    reg_data: std_logic_vector (31 downto 0);
    reset_value: std_logic_vector (31 downto 0);
    expected: std_logic_vector (31 downto 0);
    size: enum_size;
  end record;
  type registers is array(255 downto 0) of reg;


3. The main part of the test-bench is the operation of the record array:
   
     process(clk)
     variable prt_cnt : integer := 10;
     variable addrv : integer;
     variable my_line : line;
     begin
       if(clk'event and clk = '1') then
         da <= da + x"00000001";
         addr <= addr + 2;
         --
         r_reg.reg_data <= da;
         a_reg(addr).reg_data <= da;
         if(prt_cnt /= 0) then
           prt_cnt := prt_cnt-1;
           if(addr > 0) then addrv := addr-2; else addrv := 0; end if;
           write(my_line, string'("dbg "));
           hwrite(my_line, a_reg(addrv).reg_data);
           write(my_line, string'(" "));
           write(my_line, addrv);
           write(my_line, string'(" at "));
           write(my_line, now);
           writeline(output, my_line);
         end if;
       end if;
     end process;
   


4. The GHDL commands to create the simulation executable:
   
   #!/bin/bash
   ghdl -a --ieee=synopsys --workdir=work --work=work pkg.vhd
   ghdl -a --ieee=synopsys --workdir=work --work=work tb_1.vhd
   ghdl -e --workdir=work --ieee=synopsys kuku_TSB
   


5. To download, simply go to dowmload are (see below) and look for vhdl_record_array.tar.gz.

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