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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
+
+package MVL4 is
+
+ type MVL4_ulogic is ('X', '0', '1', 'Z'); -- unresolved logic type
+
+ type MVL4_ulogic_vector is array (natural range <>) of MVL4_ulogic;
+
+ function resolve_MVL4 ( contribution : MVL4_ulogic_vector )
+ return MVL4_ulogic;
+
+ subtype MVL4_logic is resolve_MVL4 MVL4_ulogic;
+
+ -- code from book (in text)
+
+ type MVL4_logic_vector is array (natural range <>) of MVL4_logic;
+
+ -- end code from book
+
+end package MVL4;
+
+--------------------------------------------------
+
+package body MVL4 is
+
+ type table is array (MVL4_ulogic, MVL4_ulogic) of MVL4_ulogic;
+
+ constant resolution_table : table :=
+ -- 'X' '0' '1' 'Z'
+ -- ------------------
+ ( ( 'X', 'X', 'X', 'X' ), -- 'X'
+ ( 'X', '0', 'X', '0' ), -- '0'
+ ( 'X', 'X', '1', '1' ), -- '1'
+ ( 'X', '0', '1', 'Z' ) ); -- 'Z'
+
+ function resolve_MVL4 ( contribution : MVL4_ulogic_vector )
+ return MVL4_ulogic is
+ variable result : MVL4_ulogic := 'Z';
+ begin
+ for index in contribution'range loop
+ result := resolution_table(result, contribution(index));
+ end loop;
+ return result;
+ end function resolve_MVL4;
+
+end package body MVL4;