com.amazonaws.services.simpleworkflow.flow.worker.CircularLongBuffer Maven / Gradle / Ivy

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The Amazon Web Services SDK for Java provides Java APIs for building software on AWS' cost-effective, scalable, and reliable infrastructure products. The AWS Java SDK allows developers to code against APIs for all of Amazon's infrastructure web services (Amazon S3, Amazon EC2, Amazon SQS, Amazon Relational Database Service, Amazon AutoScaling, etc).

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/*
 * Copyright 2012-2014 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file is distributed
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

package com.amazonaws.services.simpleworkflow.flow.worker;

class CircularLongBuffer {

    private long[] values_;
    
    public CircularLongBuffer(int size) {
        values_ = new long[size];
    }
    
    public CircularLongBuffer(long[] values) {
        values_ = values;
    }
    
    public void set(long i, long value) {
        values_[getArrayOffset(i)] = value;
    };
    
    public long get(long i) {
        return values_[getArrayOffset(i)];
    };
    
    public int size() {
        return values_.length;
    };
    
    public CircularLongBuffer copy(long index1, int length) {
        if (length == 0) {
           return new CircularLongBuffer(0);
        } 
        int i1 = getArrayOffset(index1);
        int i2 = getArrayOffset(index1 + Math.min(length, values_.length));
        long[] result = new long[length]; 
        if (i1 < i2) {
            int l = i2 - i1;
            System.arraycopy(values_, i1, result, 0, l);
        } else {
            int tailLength = values_.length - i1;
            System.arraycopy(values_, i1, result, 0, tailLength);
            System.arraycopy(values_, 0, result, tailLength, i2);
        }
        return new CircularLongBuffer(result);
    }
    
    private int getArrayOffset(long index) {
        if (values_.length == 0) {
            throw new IllegalStateException("zero data size");
        }
        int result = (int) (index % values_.length);
        if (result < 0) {
            result = values_.length + result;
        }
        return result;
    }
}