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-- Copyright (C) 2002 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
library ieee; use ieee.numeric_bit.all;
package CPU_types is
subtype word is unsigned(0 to 31);
subtype byte is unsigned(0 to 7);
alias convert_to_natural is
to_integer [ unsigned 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
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