src/loops/LoopHelpers.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 */

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:	1.7
Committed:	Sat Feb 16 21:37:44 2013 UTC (11 years, 4 months ago) by jsr166
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.6:	+6 -0 lines
Log Message:	add missing public domain notices
#	User	Rev	Content
1	jsr166	1.7	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3			* Expert Group and released to the public domain, as explained at
4			* http://creativecommons.org/publicdomain/zero/1.0/
5			*/
6
7	jsr166	1.6	import java.util.concurrent.*;
8			import java.util.concurrent.atomic.*;
9
10	jsr166	1.1	/**
11			* Misc utilities in JSR166 performance tests
12			*/
13			class LoopHelpers {
14
15			static final SimpleRandom staticRNG = new SimpleRandom();
16
17			// Some mindless computation to do between synchronizations...
18
19			/**
20	peierls	1.2	* generates 32 bit pseudo-random numbers.
21	jsr166	1.1	* Adapted from http://www.snippets.org
22			*/
23	peierls	1.2	public static int compute1(int x) {
24	jsr166	1.1	int lo = 16807 * (x & 0xFFFF);
25			int hi = 16807 * (x >>> 16);
26			lo += (hi & 0x7FFF) << 16;
27			if ((lo & 0x80000000) != 0) {
28			lo &= 0x7fffffff;
29			++lo;
30			}
31			lo += hi >>> 15;
32			if (lo == 0 \|\| (lo & 0x80000000) != 0) {
33			lo &= 0x7fffffff;
34			++lo;
35			}
36			return lo;
37			}
38
39			/**
40	jsr166	1.5	* Computes a linear congruential random number a random number
41			* of times.
42	jsr166	1.1	*/
43	peierls	1.2	public static int compute2(int x) {
44	jsr166	1.1	int loops = (x >>> 4) & 7;
45			while (loops-- > 0) {
46			x = (x * 2147483647) % 16807;
47			}
48			return x;
49			}
50
51	peierls	1.2	/**
52			* Yet another random number generator
53			*/
54			public static int compute3(int x) {
55	jsr166	1.1	int t = (x % 127773) * 16807 - (x / 127773) * 2836;
56	jsr166	1.3	return (t > 0) ? t : t + 0x7fffffff;
57	jsr166	1.1	}
58
59			/**
60	peierls	1.2	* Yet another random number generator
61			*/
62			public static int compute4(int x) {
63			return x * 134775813 + 1;
64			}
65
66			/**
67	jsr166	1.1	* An actually useful random number generator, but unsynchronized.
68			* Basically same as java.util.Random.
69			*/
70			public static class SimpleRandom {
71	jsr166	1.4	private static final long multiplier = 0x5DEECE66DL;
72			private static final long addend = 0xBL;
73			private static final long mask = (1L << 48) - 1;
74	jsr166	1.1	static final AtomicLong seq = new AtomicLong(1);
75			private long seed = System.nanoTime() + seq.getAndIncrement();
76
77			public void setSeed(long s) {
78			seed = s;
79			}
80
81			public int next() {
82			long nextseed = (seed * multiplier + addend) & mask;
83			seed = nextseed;
84			return ((int)(nextseed >>> 17)) & 0x7FFFFFFF;
85			}
86			}
87
88			public static class BarrierTimer implements Runnable {
89			public volatile long startTime;
90			public volatile long endTime;
91			public void run() {
92			long t = System.nanoTime();
93			if (startTime == 0)
94			startTime = t;
95			else
96			endTime = t;
97			}
98			public void clear() {
99			startTime = 0;
100			endTime = 0;
101			}
102			public long getTime() {
103			return endTime - startTime;
104			}
105			}
106
107			public static String rightJustify(long n) {
108			// There's probably a better way to do this...
109			String field = " ";
110			String num = Long.toString(n);
111			if (num.length() >= field.length())
112			return num;
113			StringBuffer b = new StringBuffer(field);
114			b.replace(b.length()-num.length(), b.length(), num);
115			return b.toString();
116			}
117	peierls	1.2
118	jsr166	1.1	}