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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
-- code from book (in text)
entity computer_system is
generic ( instrumented : boolean := false );
port ( -- . . . );
-- not in book
other_port : in bit := '0' );
-- end not in book
end entity computer_system;
-- end code from book
-- code from book
architecture block_level of computer_system is
-- . . . -- type and component declarations for cpu and memory, etc
signal clock : bit; -- the system clock
signal mem_req : bit; -- cpu access request to memory
signal ifetch : bit; -- indicates access is to fetch an instruction
signal write : bit; -- indicates access is a write
-- . . . -- other signal declarations
begin
-- . . . -- component instances for cpu and memory, etc
instrumentation : if instrumented generate
signal ifetch_freq, write_freq, read_freq : real := 0.0;
begin
access_monitor : process is
variable access_count, ifetch_count,
write_count, read_count : natural := 0;
begin
wait until mem_req = '1';
if ifetch = '1' then
ifetch_count := ifetch_count + 1;
elsif write = '1' then
write_count := write_count + 1;
else
read_count := read_count + 1;
end if;
access_count := access_count + 1;
ifetch_freq <= real(ifetch_count) / real(access_count);
write_freq <= real(write_count) / real(access_count);
read_freq <= real(read_count) / real(access_count);
end process access_monitor;
end generate instrumentation;
-- not in book
stimulus : process is
begin
ifetch <= '1'; write <= '0';
mem_req <= '1', '0' after 10 ns;
wait for 20 ns;
mem_req <= '1', '0' after 10 ns;
ifetch <= '1'; write <= '0';
wait for 20 ns;
mem_req <= '1', '0' after 10 ns;
ifetch <= '1'; write <= '0';
wait for 20 ns;
mem_req <= '1', '0' after 10 ns;
ifetch <= '0'; write <= '1';
wait for 20 ns;
mem_req <= '1', '0' after 10 ns;
ifetch <= '1'; write <= '0';
wait for 20 ns;
mem_req <= '1', '0' after 10 ns;
ifetch <= '0'; write <= '0';
wait for 20 ns;
mem_req <= '1', '0' after 10 ns;
ifetch <= '1'; write <= '0';
wait for 20 ns;
mem_req <= '1', '0' after 10 ns;
ifetch <= '0'; write <= '0';
wait for 20 ns;
mem_req <= '1', '0' after 10 ns;
ifetch <= '1'; write <= '0';
wait for 20 ns;
mem_req <= '1', '0' after 10 ns;
ifetch <= '0'; write <= '0';
wait for 20 ns;
wait;
end process stimulus;
-- end not in book
end architecture block_level;
-- end code from book
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