01: /*
02: * logbitp.java
03: *
04: * Copyright (C) 2003 Peter Graves
05: * $Id: logbitp.java,v 1.6 2003/11/15 11:03:34 beedlem Exp $
06: *
07: * This program is free software; you can redistribute it and/or
08: * modify it under the terms of the GNU General Public License
09: * as published by the Free Software Foundation; either version 2
10: * of the License, or (at your option) any later version.
11: *
12: * This program is distributed in the hope that it will be useful,
13: * but WITHOUT ANY WARRANTY; without even the implied warranty of
14: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15: * GNU General Public License for more details.
16: *
17: * You should have received a copy of the GNU General Public License
18: * along with this program; if not, write to the Free Software
19: * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
20: */
21:
22: package org.armedbear.lisp;
23:
24: import java.math.BigInteger;
25:
26: // ### logbitp
27: // logbitp index integer => generalized-boolean
28: public final class logbitp extends Primitive2 {
29: private logbitp(String name) {
30: super (name);
31: }
32:
33: public LispObject execute(LispObject first, LispObject second)
34: throws ConditionThrowable {
35: int index = -1;
36: if (first instanceof Fixnum) {
37: index = ((Fixnum) first).getValue();
38: } else if (first instanceof Bignum) {
39: // FIXME If the number is really big, we're not checking the right
40: // bit...
41: if (((Bignum) first).getValue().signum() > 0)
42: index = Integer.MAX_VALUE;
43: }
44: if (index < 0)
45: throw new ConditionThrowable(new TypeError(first,
46: "non-negative integer"));
47: BigInteger n;
48: if (second instanceof Fixnum)
49: n = ((Fixnum) second).getBigInteger();
50: else if (second instanceof Bignum)
51: n = ((Bignum) second).getValue();
52: else
53: throw new ConditionThrowable(new TypeError(second,
54: "integer"));
55: // FIXME See above.
56: if (index == Integer.MAX_VALUE)
57: return n.signum() < 0 ? T : NIL;
58: return n.testBit(index) ? T : NIL;
59: }
60:
61: private static final logbitp LOGBITP = new logbitp("logbitp");
62: }
|