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

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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;
    }
}