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-- 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_17_fg_17_11.vhd,v 1.2 2001-10-26 16:29:36 paw Exp $
-- $Revision: 1.2 $
--
-- ---------------------------------------------------------------------
package body bounded_buffer_adt is
function new_bounded_buffer ( size : in positive ) return bounded_buffer is
begin
return new bounded_buffer_object'(
byte_count => 0, head_index => 0, tail_index => 0,
store => new store_array(0 to size - 1) );
end function new_bounded_buffer;
procedure test_empty ( variable the_bounded_buffer : in bounded_buffer;
is_empty : out boolean ) is
begin
is_empty := the_bounded_buffer.byte_count = 0;
end procedure test_empty;
procedure test_full ( variable the_bounded_buffer : in bounded_buffer;
is_full : out boolean ) is
begin
is_full := the_bounded_buffer.byte_count = the_bounded_buffer.store'length;
end procedure test_full;
procedure write ( the_bounded_buffer : inout bounded_buffer; data : in byte ) is
variable buffer_full : boolean;
begin
test_full(the_bounded_buffer, buffer_full);
if buffer_full then
report "write to full bounded buffer" severity failure;
else
the_bounded_buffer.store(the_bounded_buffer.tail_index) := data;
the_bounded_buffer.tail_index := (the_bounded_buffer.tail_index + 1)
mod the_bounded_buffer.store'length;
the_bounded_buffer.byte_count := the_bounded_buffer.byte_count + 1;
end if;
end procedure write;
procedure read ( the_bounded_buffer : inout bounded_buffer; data : out byte ) is
variable buffer_empty : boolean;
begin
test_empty(the_bounded_buffer, buffer_empty);
if buffer_empty then
report "read from empty bounded buffer" severity failure;
else
data := the_bounded_buffer.store(the_bounded_buffer.head_index);
the_bounded_buffer.head_index := (the_bounded_buffer.head_index + 1)
mod the_bounded_buffer.store'length;
the_bounded_buffer.byte_count := the_bounded_buffer.byte_count - 1;
end if;
end procedure read;
end package body bounded_buffer_adt;
-- not in book
entity fg_17_11 is
end entity fg_17_11;
architecture test of fg_17_11 is
begin
process is
use work.bounded_buffer_adt.all;
variable buf : bounded_buffer := new_bounded_buffer(4);
variable empty, full : boolean;
variable d : byte;
begin
test_empty(buf, empty);
assert empty;
test_full(buf, full);
assert not full;
write(buf, X"01");
write(buf, X"02");
test_empty(buf, empty);
assert not empty;
test_full(buf, full);
assert not full;
write(buf, X"03");
write(buf, X"04");
test_empty(buf, empty);
assert not empty;
test_full(buf, full);
assert full;
write(buf, X"05");
read(buf, d);
read(buf, d);
test_empty(buf, empty);
assert not empty;
test_full(buf, full);
assert not full;
read(buf, d);
read(buf, d);
test_empty(buf, empty);
assert empty;
test_full(buf, full);
assert not full;
read(buf, d);
write(buf, X"06");
write(buf, X"07");
write(buf, X"08");
read(buf, d);
read(buf, d);
write(buf, X"09");
read(buf, d);
write(buf, X"0A");
read(buf, d);
write(buf, X"0B");
read(buf, d);
write(buf, X"0C");
read(buf, d);
write(buf, X"0D");
read(buf, d);
write(buf, X"0E");
read(buf, d);
write(buf, X"0F");
read(buf, d);
wait;
end process;
end architecture test;
-- end not in book
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