CristalCaveGem » LustreC » Lustrec-Tests

-- Copyright (C) 1996 Morgan Kaufmann Publishers, Inc

-- This file is part of VESTs (Vhdl tESTs).

-- VESTs is free software; you can redistribute it and/or modify it

-- under the terms of the GNU General Public License as published by the

-- Free Software Foundation; either version 2 of the License, or (at

-- your option) any later version. 

-- VESTs is distributed in the hope that it will be useful, but WITHOUT

-- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

-- FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

-- for more details. 

-- You should have received a copy of the GNU General Public License

-- along with VESTs; if not, write to the Free Software Foundation,

-- Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 

-- ---------------------------------------------------------------------

--

-- $Id: ch_18_fg_18_03.vhd,v 1.3 2001-10-26 16:29:36 paw Exp $

-- $Revision: 1.3 $

--

-- ---------------------------------------------------------------------

library bv_utilities;

package CPU_types is

  subtype word is bit_vector(0 to 31);

  subtype byte is bit_vector(0 to 7);

  alias convert_to_natural is

    bv_utilities.bv_arithmetic.bv_to_natural [ bit_vector return natural ];

  constant halt_opcode : byte := "00000000";

  type code_array is array (natural range <>) of word;

  constant code : code_array := ( X"01000000", X"01000000", X"02000000",

				  X"01000000", X"01000000", X"02000000",

				  X"00000000" );

end package CPU_types;

use work.CPU_types.all;

entity CPU is

end entity CPU;

-- code from book

architecture instrumented of CPU is

  type count_file is file of natural;

  file instruction_counts : count_file open write_mode is "instructions";

begin

  interpreter : process is

                          variable IR : word;

                        alias opcode : byte is IR(0 to 7);

                        variable opcode_number : natural;

                        type counter_array is array (0 to 2**opcode'length - 1) of natural;

                        variable counters : counter_array := (others => 0);

                        -- . . .

                        -- not in book

                        variable code_index : natural := 0;

                        -- end not in book

  begin

    -- . . .    -- initialize the instruction set interpreter

    instruction_loop : loop

      -- . . .    -- fetch the next instruction into IR

      -- not in book

      IR := code(code_index);

      code_index := code_index + 1;

      -- end not in book

      -- decode the instruction

      opcode_number := convert_to_natural(opcode);

      counters(opcode_number) := counters(opcode_number) + 1;

      -- . . .

      -- execute the decoded instruction

      case opcode is

        -- . . .

        when halt_opcode => exit instruction_loop;

                            -- . . .

                            -- not in book

        when others => null;

                       -- end not in book

      end case;

    end loop instruction_loop;

    for index in counters'range loop

      write(instruction_counts, counters(index));

    end loop;

    wait;  -- program finished, wait forever

  end process interpreter;

end architecture instrumented;

-- code from book