1 /*
2 * Copyright (c) 2001, Zoltan Farkas All Rights Reserved.
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 */
18
19 package net.sf.zel.instr;
20
21 import net.sf.zel.nr.Operable;
22 import net.sf.zel.vm.*;
23
24 public final class SUB extends Instruction
25 {
26 private static final long serialVersionUID = 2469612346855489913L;
27
28 private SUB(){};
29
30 public void execute(ExecutionContext context) throws ZExecutionException
31 {
32 final Operable val1 = (Operable) context.popSyncStackVal();
33 final Operable val2 = (Operable) context.popSyncStackVal();
34
35 if (val1 != null && val2 != null)
36 {
37 context.stack.push(val2.subtract(val1));
38 } else
39 {
40 context.stack.push(null);
41 }
42 context.ip++;
43 }
44 /**
45 * instance
46 */
47 public static final Instruction instance = new SUB();
48 }