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Common Lisp implementation running on the JVM
There is a newer version: 1.9.2
/*
 * float_sign.java
 *
 * Copyright (C) 2004-2005 Peter Graves
 * $Id$
 *
 * This program 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.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * As a special exception, the copyright holders of this library give you
 * permission to link this library with independent modules to produce an
 * executable, regardless of the license terms of these independent
 * modules, and to copy and distribute the resulting executable under
 * terms of your choice, provided that you also meet, for each linked
 * independent module, the terms and conditions of the license of that
 * module.  An independent module is a module which is not derived from
 * or based on this library.  If you modify this library, you may extend
 * this exception to your version of the library, but you are not
 * obligated to do so.  If you do not wish to do so, delete this
 * exception statement from your version.
 */

package org.armedbear.lisp;

import static org.armedbear.lisp.Lisp.*;

// ### float-sign
public final class float_sign extends Primitive
{
    private float_sign()
    {
        super("float-sign", "float-1 &optional float-2");
    }

    @Override
    public LispObject execute(LispObject arg)
    {
        if (arg instanceof SingleFloat) {
            float f = ((SingleFloat)arg).value;
            int bits = Float.floatToRawIntBits(f);
            return bits < 0 ? SingleFloat.MINUS_ONE : SingleFloat.ONE;
        }
        if (arg instanceof DoubleFloat) {
            double d = ((DoubleFloat)arg).value;
            long bits = Double.doubleToRawLongBits(d);
            return bits < 0 ? DoubleFloat.MINUS_ONE : DoubleFloat.ONE;
        }
        return type_error(arg, Symbol.FLOAT);
    }

    @Override
    public LispObject execute(LispObject first, LispObject second)

    {
        if (!first.floatp())
            return type_error(first, Symbol.FLOAT);
        if (!second.floatp())
            return type_error(second, Symbol.FLOAT);
        if (first.minusp()) {
            if (second.minusp())
                return second;
            else
                return Fixnum.ZERO.subtract(second);
        } else
            return second.ABS();
    }

    private static final Primitive FLOAT_SIGN = new float_sign();
}