src/loops/LoopHelpers.java

/**
 * Misc utilities in JSR166 performance tests
 */

import java.util.concurrent.*;
import java.util.concurrent.atomic.*;

class LoopHelpers {

    static final SimpleRandom staticRNG = new SimpleRandom();

    // Some mindless computation to do between synchronizations...

    /**
     * generates 32 bit pseudo-random numbers.
     * Adapted from http://www.snippets.org
     */
    public static int compute1(int x) {
        int lo = 16807 * (x & 0xFFFF);
        int hi = 16807 * (x >>> 16);
        lo += (hi & 0x7FFF) << 16;
        if ((lo & 0x80000000) != 0) {
            lo &= 0x7fffffff;
            ++lo;
        }
        lo += hi >>> 15;
        if (lo == 0 || (lo & 0x80000000) != 0) {
            lo &= 0x7fffffff;
            ++lo;
        }
        return lo;
    }

    /**
     *  Computes a linear congruential random number a random number
     *  of times.
     */
    public static int compute2(int x) {
        int loops = (x >>> 4) & 7;
        while (loops-- > 0) {
            x = (x * 2147483647) % 16807;
        }
        return x;
    }

    /**
     * Yet another random number generator
     */
    public static int compute3(int x) {
        int t = (x % 127773) * 16807 - (x / 127773) * 2836;
        return (t > 0) ? t : t + 0x7fffffff;
    }

    /**
     * Yet another random number generator
     */
    public static int compute4(int x) {
        return x * 134775813 + 1;
    }

    /**
     * An actually useful random number generator, but unsynchronized.
     * Basically same as java.util.Random.
     */
    public static class SimpleRandom {
        private final static long multiplier = 0x5DEECE66DL;
        private final static long addend = 0xBL;
        private final static long mask = (1L << 48) - 1;
        static final AtomicLong seq = new AtomicLong(1);
        private long seed = System.nanoTime() + seq.getAndIncrement();

        public void setSeed(long s) {
            seed = s;
        }

        public int next() {
            long nextseed = (seed * multiplier + addend) & mask;
            seed = nextseed;
            return ((int)(nextseed >>> 17)) & 0x7FFFFFFF;
        }
    }

    public static class BarrierTimer implements Runnable {
        public volatile long startTime;
        public volatile long endTime;
        public void run() {
            long t = System.nanoTime();
            if (startTime == 0)
                startTime = t;
            else
                endTime = t;
        }
        public void clear() {
            startTime = 0;
            endTime = 0;
        }
        public long getTime() {
            return endTime - startTime;
        }
    }

    public static String rightJustify(long n) {
        // There's probably a better way to do this...
        String field = "         ";
        String num = Long.toString(n);
        if (num.length() >= field.length())
            return num;
        StringBuffer b = new StringBuffer(field);
        b.replace(b.length()-num.length(), b.length(), num);
        return b.toString();
    }

}
Revision:	1.3
Committed:	Fri Oct 22 05:18:30 2010 UTC (13 years, 8 months ago) by jsr166
Branch:	MAIN
CVS Tags:	release-1_7_0
Changes since 1.2:	+1 -1 lines
Log Message:	whitespace
#	Content
1	/**
2	* Misc utilities in JSR166 performance tests
3	*/
4
5	import java.util.concurrent.*;
6	import java.util.concurrent.atomic.*;
7
8	class LoopHelpers {
9
10	static final SimpleRandom staticRNG = new SimpleRandom();
11
12	// Some mindless computation to do between synchronizations...
13
14	/**
15	* generates 32 bit pseudo-random numbers.
16	* Adapted from http://www.snippets.org
17	*/
18	public static int compute1(int x) {
19	int lo = 16807 * (x & 0xFFFF);
20	int hi = 16807 * (x >>> 16);
21	lo += (hi & 0x7FFF) << 16;
22	if ((lo & 0x80000000) != 0) {
23	lo &= 0x7fffffff;
24	++lo;
25	}
26	lo += hi >>> 15;
27	if (lo == 0 \|\| (lo & 0x80000000) != 0) {
28	lo &= 0x7fffffff;
29	++lo;
30	}
31	return lo;
32	}
33
34	/**
35	* Computes a linear congruential random number a random number
36	* of times.
37	*/
38	public static int compute2(int x) {
39	int loops = (x >>> 4) & 7;
40	while (loops-- > 0) {
41	x = (x * 2147483647) % 16807;
42	}
43	return x;
44	}
45
46	/**
47	* Yet another random number generator
48	*/
49	public static int compute3(int x) {
50	int t = (x % 127773) * 16807 - (x / 127773) * 2836;
51	return (t > 0) ? t : t + 0x7fffffff;
52	}
53
54	/**
55	* Yet another random number generator
56	*/
57	public static int compute4(int x) {
58	return x * 134775813 + 1;
59	}
60
61	/**
62	* An actually useful random number generator, but unsynchronized.
63	* Basically same as java.util.Random.
64	*/
65	public static class SimpleRandom {
66	private final static long multiplier = 0x5DEECE66DL;
67	private final static long addend = 0xBL;
68	private final static long mask = (1L << 48) - 1;
69	static final AtomicLong seq = new AtomicLong(1);
70	private long seed = System.nanoTime() + seq.getAndIncrement();
71
72	public void setSeed(long s) {
73	seed = s;
74	}
75
76	public int next() {
77	long nextseed = (seed * multiplier + addend) & mask;
78	seed = nextseed;
79	return ((int)(nextseed >>> 17)) & 0x7FFFFFFF;
80	}
81	}
82
83	public static class BarrierTimer implements Runnable {
84	public volatile long startTime;
85	public volatile long endTime;
86	public void run() {
87	long t = System.nanoTime();
88	if (startTime == 0)
89	startTime = t;
90	else
91	endTime = t;
92	}
93	public void clear() {
94	startTime = 0;
95	endTime = 0;
96	}
97	public long getTime() {
98	return endTime - startTime;
99	}
100	}
101
102	public static String rightJustify(long n) {
103	// There's probably a better way to do this...
104	String field = " ";
105	String num = Long.toString(n);
106	if (num.length() >= field.length())
107	return num;
108	StringBuffer b = new StringBuffer(field);
109	b.replace(b.length()-num.length(), b.length(), num);
110	return b.toString();
111	}
112
113	}