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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_19_wtfifo-b.vhd,v 1.3 2001-10-26 16:29:36 paw Exp $
-- $Revision: 1.3 $
--
-- ---------------------------------------------------------------------
package body waiting_token_fifo_adt is
function new_fifo return fifo_type is
begin
return new fifo_record'( null, null );
end function new_fifo;
procedure test_empty ( variable fifo : in fifo_type;
variable is_empty : out boolean ) is
begin
is_empty := fifo.head_entry = null;
end procedure test_empty;
procedure insert ( fifo : inout fifo_type;
element : in element_type ) is
variable new_entry : fifo_entry
:= new fifo_entry_record'( next_entry => null,
element => element );
begin
if fifo.tail_entry /= null then
fifo.tail_entry.next_entry := new_entry;
else
fifo.head_entry := new_entry;
end if;
fifo.tail_entry := new_entry;
end procedure insert;
procedure remove ( fifo : inout fifo_type;
element : out element_type ) is
variable empty_fifo : boolean;
variable removed_entry : fifo_entry;
begin
test_empty(fifo, empty_fifo);
if empty_fifo then
report "remove from empty fifo" severity failure;
else
removed_entry := fifo.head_entry;
element := removed_entry.element;
fifo.head_entry := removed_entry.next_entry;
if fifo.head_entry = null then -- fifo now empty
fifo.tail_entry := null;
end if;
deallocate(removed_entry);
end if;
end procedure remove;
end package body waiting_token_fifo_adt;
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