core/src/core/org/jnode/vm/MathSupport.java - new-gc-algorithms in JNode

/*
 * $Id$
 *
 * Copyright (C) 2003-2009 JNode.org
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public 
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; If not, write to the Free Software Foundation, Inc., 
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

package org.jnode.vm;

import org.jnode.annotation.MagicPermission;
import org.jnode.annotation.Uninterruptible;


/**
 * In MathSupport ldiv and lrem will be used as SoftBytecodes. I.e. normal Java classes that contain ldiv or
 * lrem bytecodes will in fact call these Java methods.
 *
 * @author epr
 * @author peda
 */
@MagicPermission
@Uninterruptible
public final class MathSupport {

    /**
     * New Implementation
     */
    public static long ldiv(long num, long den) {
        if (num == Long.MIN_VALUE) {
            if (den == Long.MIN_VALUE) {
                return 1;
            } else {
                long q = ldiv(num + 1, den);
                long r = num + 1 - q * den;
                if (Math.abs(r) == Math.abs(den) - 1) {
                    return q < 0 ? q - 1 : q + 1;
                } else {
                    return q;
                }
            }
        }

        if (den == Long.MIN_VALUE) {
            return 0;
        }

        boolean neg = false;
        if (num < 0) {
            num = -num;
            neg = true;
        }
        if (den < 0) {
            den = -den;
            neg = !neg;
        }
        if (num < den) return 0;
        if (den == 0) throw new ArithmeticException("Divide by zero");

        long qBit = 1;
        while (den >= 0) {
            den = den << 1;
            qBit = qBit << 1;
        }

        den >>>= 1;
        qBit >>>= 1;

        long result = 0;
        while (qBit != 0) {
            if (den <= num) {
                result += qBit;
                num -= den;
            }
            den = den >>> 1;
            qBit = qBit >>> 1;
        }

        if (neg)
            return -result;
        return result;
    }
    /**
     * new implementation
     */
    public static long lrem(long num, long den) {
        if (num == Long.MIN_VALUE) {
            if (den == Long.MIN_VALUE) {
                return 0;
            } else {
                long r = lrem(num + 1, den);
                if (Math.abs(r) == Math.abs(den) - 1) {
                    return 0;
                } else {
                    return r < 0 ? r - 1 : r > 0 ? r + 1 : -1;
                }
            }
        }

        if (den == Long.MIN_VALUE) {
            return num;
        }

        final boolean neg;
        if (num < 0) {
            num = -num;
            neg = true;
        } else neg = false;
        if (den < 0) {
            den = -den;
        }
        if (num < den) return neg ? -num : num;

        if (den == 0)
            throw new ArithmeticException("Divide by zero");

        long qBit = 1;
        while (den >= 0) {
            den <<= 1;
            qBit <<= 1;
        }

        den >>>= 1;
        qBit >>>= 1;

        while (qBit != 0) {
            if (den <= num) {
                num -= den;
            }
            qBit >>>= 1;
            den >>>= 1;
        }

        if (neg)
            return -num;
        return num;
    }
}

1	/*
2	* $Id$
3	*
4	* Copyright (C) 2003-2009 JNode.org
5	*
6	* This library is free software; you can redistribute it and/or modify it
7	* under the terms of the GNU Lesser General Public License as published
8	* by the Free Software Foundation; either version 2.1 of the License, or
9	* (at your option) any later version.
10	*
11	* This library is distributed in the hope that it will be useful, but
12	* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13	* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
14	* License for more details.
15	*
16	* You should have received a copy of the GNU Lesser General Public License
17	* along with this library; If not, write to the Free Software Foundation, Inc.,
18	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
19	*/
20
21	package org.jnode.vm;
22
23	import org.jnode.annotation.MagicPermission;
24	import org.jnode.annotation.Uninterruptible;
25
26
27	/**
28	* In MathSupport ldiv and lrem will be used as SoftBytecodes. I.e. normal Java classes that contain ldiv or
29	* lrem bytecodes will in fact call these Java methods.
30	*
31	* @author epr
32	* @author peda
33	*/
34	@MagicPermission
35	@Uninterruptible
36	public final class MathSupport {
37
38	/**
39	* New Implementation
40	*/
41	public static long ldiv(long num, long den) {
42	if (num == Long.MIN_VALUE) {
43	if (den == Long.MIN_VALUE) {
44	return 1;
45	} else {
46	long q = ldiv(num + 1, den);
47	long r = num + 1 - q * den;
48	if (Math.abs(r) == Math.abs(den) - 1) {
49	return q < 0 ? q - 1 : q + 1;
50	} else {
51	return q;
52	}
53	}
54	}
55
56	if (den == Long.MIN_VALUE) {
57	return 0;
58	}
59
60	boolean neg = false;
61	if (num < 0) {
62	num = -num;
63	neg = true;
64	}
65	if (den < 0) {
66	den = -den;
67	neg = !neg;
68	}
69	if (num < den) return 0;
70	if (den == 0) throw new ArithmeticException("Divide by zero");
71
72	long qBit = 1;
73	while (den >= 0) {
74	den = den << 1;
75	qBit = qBit << 1;
76	}
77
78	den >>>= 1;
79	qBit >>>= 1;
80
81	long result = 0;
82	while (qBit != 0) {
83	if (den <= num) {
84	result += qBit;
85	num -= den;
86	}
87	den = den >>> 1;
88	qBit = qBit >>> 1;
89	}
90
91	if (neg)
92	return -result;
93	return result;
94	}
95	/**
96	* new implementation
97	*/
98	public static long lrem(long num, long den) {
99	if (num == Long.MIN_VALUE) {
100	if (den == Long.MIN_VALUE) {
101	return 0;
102	} else {
103	long r = lrem(num + 1, den);
104	if (Math.abs(r) == Math.abs(den) - 1) {
105	return 0;
106	} else {
107	return r < 0 ? r - 1 : r > 0 ? r + 1 : -1;
108	}
109	}
110	}
111
112	if (den == Long.MIN_VALUE) {
113	return num;
114	}
115
116	final boolean neg;
117	if (num < 0) {
118	num = -num;
119	neg = true;
120	} else neg = false;
121	if (den < 0) {
122	den = -den;
123	}
124	if (num < den) return neg ? -num : num;
125
126	if (den == 0)
127	throw new ArithmeticException("Divide by zero");
128
129	long qBit = 1;
130	while (den >= 0) {
131	den <<= 1;
132	qBit <<= 1;
133	}
134
135	den >>>= 1;
136	qBit >>>= 1;
137
138	while (qBit != 0) {
139	if (den <= num) {
140	num -= den;
141	}
142	qBit >>>= 1;
143	den >>>= 1;
144	}
145
146	if (neg)
147	return -num;
148	return num;
149	}
150	}

Gitorious