src/loops/LoopHelpers.java

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

/**
 * Misc utilities in JSR166 performance tests
 */
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 static final long multiplier = 0x5DEECE66DL;
        private static final long addend = 0xBL;
        private static final 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:	1.6
Committed:	Sat Feb 16 20:50:29 2013 UTC (11 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.5:	+3 -4 lines
Log Message:	javadoc comment correctness
#	Content
1	import java.util.concurrent.*;
2	import java.util.concurrent.atomic.*;
3
4	/**
5	* Misc utilities in JSR166 performance tests
6	*/
7	class LoopHelpers {
8
9	static final SimpleRandom staticRNG = new SimpleRandom();
10
11	// Some mindless computation to do between synchronizations...
12
13	/**
14	* generates 32 bit pseudo-random numbers.
15	* Adapted from http://www.snippets.org
16	*/
17	public static int compute1(int x) {
18	int lo = 16807 * (x & 0xFFFF);
19	int hi = 16807 * (x >>> 16);
20	lo += (hi & 0x7FFF) << 16;
21	if ((lo & 0x80000000) != 0) {
22	lo &= 0x7fffffff;
23	++lo;
24	}
25	lo += hi >>> 15;
26	if (lo == 0 \|\| (lo & 0x80000000) != 0) {
27	lo &= 0x7fffffff;
28	++lo;
29	}
30	return lo;
31	}
32
33	/**
34	* Computes a linear congruential random number a random number
35	* of times.
36	*/
37	public static int compute2(int x) {
38	int loops = (x >>> 4) & 7;
39	while (loops-- > 0) {
40	x = (x * 2147483647) % 16807;
41	}
42	return x;
43	}
44
45	/**
46	* Yet another random number generator
47	*/
48	public static int compute3(int x) {
49	int t = (x % 127773) * 16807 - (x / 127773) * 2836;
50	return (t > 0) ? t : t + 0x7fffffff;
51	}
52
53	/**
54	* Yet another random number generator
55	*/
56	public static int compute4(int x) {
57	return x * 134775813 + 1;
58	}
59
60	/**
61	* An actually useful random number generator, but unsynchronized.
62	* Basically same as java.util.Random.
63	*/
64	public static class SimpleRandom {
65	private static final long multiplier = 0x5DEECE66DL;
66	private static final long addend = 0xBL;
67	private static final long mask = (1L << 48) - 1;
68	static final AtomicLong seq = new AtomicLong(1);
69	private long seed = System.nanoTime() + seq.getAndIncrement();
70
71	public void setSeed(long s) {
72	seed = s;
73	}
74
75	public int next() {
76	long nextseed = (seed * multiplier + addend) & mask;
77	seed = nextseed;
78	return ((int)(nextseed >>> 17)) & 0x7FFFFFFF;
79	}
80	}
81
82	public static class BarrierTimer implements Runnable {
83	public volatile long startTime;
84	public volatile long endTime;
85	public void run() {
86	long t = System.nanoTime();
87	if (startTime == 0)
88	startTime = t;
89	else
90	endTime = t;
91	}
92	public void clear() {
93	startTime = 0;
94	endTime = 0;
95	}
96	public long getTime() {
97	return endTime - startTime;
98	}
99	}
100
101	public static String rightJustify(long n) {
102	// There's probably a better way to do this...
103	String field = " ";
104	String num = Long.toString(n);
105	if (num.length() >= field.length())
106	return num;
107	StringBuffer b = new StringBuffer(field);
108	b.replace(b.length()-num.length(), b.length(), num);
109	return b.toString();
110	}
111
112	}