commons-codec-1.11.jar - Apache Commons Codec

commons-codec-1.11.jar is the JAR file for Apache Commons Codec 1.11, which provides implementations of common encoders and decoders such as Base64, Hex, Phonetic and URLs.

JAR File Size and Download Location:

JAR name: commons-codec.jar
Target JDK version: 1.8
Dependency: None
File name: commons-codec-1.11.jar
File size: 335,042 bytes
Date modified: 10/17/2017 
Download: Apache Commons Codec

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org/apache/commons/codec/digest/XXHash32.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License 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 org.apache.commons.codec.digest;

import static java.lang.Integer.rotateLeft;

import java.util.zip.Checksum;

/**
 * Implementation of the xxhash32 hash algorithm.
 *
 * <p>Copied from Commons Compress 1.14
 * <a href="https://git-wip-us.apache.org/repos/asf?p=commons-compress.git;a=blob;f=src/main/java/org/apache/commons/compress/compressors/lz4/XXHash32.java;h=a406ffc197449be594d46f0d2712b2d4786a1e68;hb=HEAD">https://git-wip-us.apache.org/repos/asf?p=commons-compress.git;a=blob;f=src/main/java/org/apache/commons/compress/compressors/lz4/XXHash32.java;h=a406ffc197449be594d46f0d2712b2d4786a1e68;hb=HEAD</a></p>
 * <p>NotThreadSafe</p>
 * @see <a href="http://cyan4973.github.io/xxHash/">xxHash</a>
 * @since 1.11
 */
public class XXHash32 implements Checksum {

    private static final int BUF_SIZE = 16;
    private static final int ROTATE_BITS = 13;

    private static final int PRIME1 = (int) 2654435761l;
    private static final int PRIME2 = (int) 2246822519l;
    private static final int PRIME3 = (int) 3266489917l;
    private static final int PRIME4 =  668265263;
    private static final int PRIME5 =  374761393;

    private final byte[] oneByte = new byte[1];
    private final int[] state = new int[4];
    // Note: the code used to use ByteBuffer but the manual method is 50% faster
    // See: http://git-wip-us.apache.org/repos/asf/commons-compress/diff/2f56fb5c
    private final byte[] buffer = new byte[BUF_SIZE];
    private final int seed;

    private int totalLen;
    private int pos;

    /**
     * Creates an XXHash32 instance with a seed of 0.
     */
    public XXHash32() {
        this(0);
    }

    /**
     * Creates an XXHash32 instance.
     * @param seed the seed to use
     */
    public XXHash32(final int seed) {
        this.seed = seed;
        initializeState();
    }

    @Override
    public void reset() {
        initializeState();
        totalLen = 0;
        pos = 0;
    }

    @Override
    public void update(final int b) {
        oneByte[0] = (byte) (b & 0xff);
        update(oneByte, 0, 1);
    }

    @Override
    public void update(final byte[] b, int off, final int len) {
        if (len <= 0) {
            return;
        }
        totalLen += len;

        final int end = off + len;

        if (pos + len < BUF_SIZE) {
            System.arraycopy(b, off, buffer, pos, len);
            pos += len;
            return;
        }

        if (pos > 0) {
            final int size = BUF_SIZE - pos;
            System.arraycopy(b, off, buffer, pos, size);
            process(buffer, 0);
            off += size;
        }

        final int limit = end - BUF_SIZE;
        while (off <= limit) {
            process(b, off);
            off += BUF_SIZE;
        }

        if (off < end) {
            pos = end - off;
            System.arraycopy(b, off, buffer, 0, pos);
        }
    }

    @Override
    public long getValue() {
        int hash;
        if (totalLen > BUF_SIZE) {
            hash =
                rotateLeft(state[0],  1) +
                rotateLeft(state[1],  7) +
                rotateLeft(state[2], 12) +
                rotateLeft(state[3], 18);
        } else {
            hash = state[2] + PRIME5;
        }
        hash += totalLen;

        int idx = 0;
        final int limit = pos - 4;
        for (; idx <= limit; idx += 4) {
            hash = rotateLeft(hash + getInt(buffer, idx) * PRIME3, 17) * PRIME4;
        }
        while (idx < pos) {
            hash = rotateLeft(hash + (buffer[idx++] & 0xff) * PRIME5, 11) * PRIME1;
        }

        hash ^= hash >>> 15;
        hash *= PRIME2;
        hash ^= hash >>> 13;
        hash *= PRIME3;
        hash ^= hash >>> 16;
        return hash & 0xffffffffl;
    }

    private static int getInt(final byte[] buffer, final int idx) {
        return (int) (fromLittleEndian(buffer, idx, 4) & 0xffffffffl);
    }

    private void initializeState() {
        state[0] = seed + PRIME1 + PRIME2;
        state[1] = seed + PRIME2;
        state[2] = seed;
        state[3] = seed - PRIME1;
    }

    private void process(final byte[] b, final int offset) {
        // local shadows for performance
        int s0 = state[0];
        int s1 = state[1];
        int s2 = state[2];
        int s3 = state[3];

        s0 = rotateLeft(s0 + getInt(b, offset) * PRIME2, ROTATE_BITS) * PRIME1;
        s1 = rotateLeft(s1 + getInt(b, offset + 4) * PRIME2, ROTATE_BITS) * PRIME1;
        s2 = rotateLeft(s2 + getInt(b, offset + 8) * PRIME2, ROTATE_BITS) * PRIME1;
        s3 = rotateLeft(s3 + getInt(b, offset + 12) * PRIME2, ROTATE_BITS) * PRIME1;

        state[0] = s0;
        state[1] = s1;
        state[2] = s2;
        state[3] = s3;

        pos = 0;
    }

    /**
     * Reads the given byte array as a little endian long.
     * @param bytes the byte array to convert
     * @param off the offset into the array that starts the value
     * @param length the number of bytes representing the value
     * @return the number read
     * @throws IllegalArgumentException if len is bigger than eight
     */
    private static long fromLittleEndian(final byte[] bytes, final int off, final int length) {
        if (length > 8) {
            throw new IllegalArgumentException("can't read more than eight bytes into a long value");
        }
        long l = 0;
        for (int i = 0; i < length; i++) {
            l |= (bytes[off + i] & 0xffl) << (8 * i);
        }
        return l;
    }
}

org/apache/commons/codec/digest/XXHash32.java

 

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