01: /*
02: * logcount.java
03: *
04: * Copyright (C) 2003 Peter Graves
05: * $Id: logcount.java,v 1.6 2003/11/15 11:03:32 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: // ### logcount
27: // logcount integer => number-of-on-bits
28: public final class logcount extends Primitive1 {
29: private logcount() {
30: super ("logcount");
31: }
32:
33: // FIXME Optimize fixnum case!
34: public LispObject execute(LispObject arg) throws ConditionThrowable {
35: BigInteger n;
36: if (arg instanceof Fixnum)
37: n = ((Fixnum) arg).getBigInteger();
38: else if (arg instanceof Bignum)
39: n = ((Bignum) arg).getValue();
40: else
41: throw new ConditionThrowable(new TypeError(arg, "integer"));
42: return new Fixnum(n.bitCount());
43: }
44:
45: private static final logcount LOGCOUNT = new logcount();
46: }
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