403 lines
12 KiB
Java
403 lines
12 KiB
Java
/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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==================================================================== */
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package org.apache.poi.util;
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import java.io.IOException;
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import java.io.InputStream;
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/**
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* a utility class for handling little-endian numbers, which the 80x86 world is
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* replete with. The methods are all static, and input/output is from/to byte
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* arrays, or from InputStreams.
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*
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*@author Marc Johnson (mjohnson at apache dot org)
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*@author Andrew Oliver (acoliver at apache dot org)
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*/
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public class LittleEndian implements LittleEndianConsts {
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private LittleEndian() {
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// no instances of this class
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}
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/**
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* get a short value from a byte array
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*
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*@param data the byte array
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*@param offset a starting offset into the byte array
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*@return the short (16-bit) value
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*/
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public static short getShort(byte[] data, int offset) {
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int b0 = data[offset] & 0xFF;
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int b1 = data[offset+1] & 0xFF;
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return (short) ((b1 << 8) + (b0 << 0));
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}
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/**
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* get an unsigned short value from a byte array
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*
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*@param data the byte array
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*@param offset a starting offset into the byte array
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*@return the unsigned short (16-bit) value in an integer
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*/
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public static int getUShort(byte[] data, int offset) {
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int b0 = data[offset] & 0xFF;
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int b1 = data[offset+1] & 0xFF;
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return (b1 << 8) + (b0 << 0);
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}
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/**
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* get a short value from the beginning of a byte array
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*
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*@param data the byte array
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*@return the short (16-bit) value
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*/
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public static short getShort(byte[] data) {
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return getShort(data, 0);
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}
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/**
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* get an unsigned short value from the beginning of a byte array
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*
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*@param data the byte array
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*@return the unsigned short (16-bit) value in an int
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*/
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public static int getUShort(byte[] data) {
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return getUShort(data, 0);
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}
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/**
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* get an int value from a byte array
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*
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*@param data the byte array
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*@param offset a starting offset into the byte array
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*@return the int (32-bit) value
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*/
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public static int getInt(byte[] data, int offset) {
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int i=offset;
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int b0 = data[i++] & 0xFF;
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int b1 = data[i++] & 0xFF;
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int b2 = data[i++] & 0xFF;
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int b3 = data[i++] & 0xFF;
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return (b3 << 24) + (b2 << 16) + (b1 << 8) + (b0 << 0);
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}
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/**
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* get an int value from the beginning of a byte array
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*
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*@param data the byte array
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*@return the int (32-bit) value
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*/
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public static int getInt(byte[] data) {
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return getInt(data, 0);
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}
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/**
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* get an unsigned int value from a byte array
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*
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*@param data the byte array
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*@param offset a starting offset into the byte array
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*@return the unsigned int (32-bit) value in a long
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*/
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public static long getUInt(byte[] data, int offset) {
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long retNum = getInt(data, offset);
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return retNum & 0x00FFFFFFFFl;
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}
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/**
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* get an unsigned int value from a byte array
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*
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*@param data the byte array
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*@return the unsigned int (32-bit) value in a long
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*/
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public static long getUInt(byte[] data) {
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return getUInt(data,0);
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}
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/**
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* get a long value from a byte array
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*
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*@param data the byte array
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*@param offset a starting offset into the byte array
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*@return the long (64-bit) value
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*/
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public static long getLong(byte[] data, int offset) {
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long result = 0;
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for (int j = offset + LONG_SIZE - 1; j >= offset; j--) {
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result <<= 8;
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result |= 0xff & data[j];
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}
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return result;
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}
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/**
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* get a double value from a byte array, reads it in little endian format
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* then converts the resulting revolting IEEE 754 (curse them) floating
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* point number to a happy java double
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*
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*@param data the byte array
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*@param offset a starting offset into the byte array
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*@return the double (64-bit) value
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*/
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public static double getDouble(byte[] data, int offset) {
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return Double.longBitsToDouble(getLong(data, offset));
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}
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/**
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* put a short value into a byte array
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*
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*@param data the byte array
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*@param offset a starting offset into the byte array
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*@param value the short (16-bit) value
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*/
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public static void putShort(byte[] data, int offset, short value) {
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int i = offset;
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data[i++] = (byte)((value >>> 0) & 0xFF);
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data[i++] = (byte)((value >>> 8) & 0xFF);
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}
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/**
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* executes:<p/>
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* <code>
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* data[offset] = (byte)value;
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* </code></p>
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* Added for consistency with other put~() methods
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*/
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public static void putByte(byte[] data, int offset, int value) {
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data[offset] = (byte) value;
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}
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/**
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* put an unsigned short value into a byte array
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*
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* @param data the byte array
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* @param offset a starting offset into the byte array
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* @param value the short (16-bit) value
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*
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* @exception ArrayIndexOutOfBoundsException may be thrown
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*/
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public static void putUShort(byte[] data, int offset, int value) {
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int i = offset;
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data[i++] = (byte)((value >>> 0) & 0xFF);
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data[i++] = (byte)((value >>> 8) & 0xFF);
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}
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/**
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* put a short value into beginning of a byte array
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*
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*@param data the byte array
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*@param value the short (16-bit) value
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*/
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public static void putShort(byte[] data, short value) {
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putShort(data, 0, value);
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}
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/**
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* put an int value into a byte array
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*
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*@param data the byte array
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*@param offset a starting offset into the byte array
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*@param value the int (32-bit) value
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*/
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public static void putInt(byte[] data, int offset, int value) {
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int i = offset;
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data[i++] = (byte)((value >>> 0) & 0xFF);
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data[i++] = (byte)((value >>> 8) & 0xFF);
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data[i++] = (byte)((value >>> 16) & 0xFF);
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data[i++] = (byte)((value >>> 24) & 0xFF);
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}
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/**
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* put an int value into beginning of a byte array
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*
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*@param data the byte array
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*@param value the int (32-bit) value
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*/
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public static void putInt(byte[] data, int value) {
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putInt(data, 0, value);
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}
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/**
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* put a long value into a byte array
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*
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*@param data the byte array
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*@param offset a starting offset into the byte array
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*@param value the long (64-bit) value
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*/
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public static void putLong(byte[] data, int offset, long value) {
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int limit = LONG_SIZE + offset;
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long v = value;
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for (int j = offset; j < limit; j++) {
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data[j] = (byte) (v & 0xFF);
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v >>= 8;
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}
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}
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/**
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* put a double value into a byte array
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*
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*@param data the byte array
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*@param offset a starting offset into the byte array
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*@param value the double (64-bit) value
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*/
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public static void putDouble(byte[] data, int offset, double value) {
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putLong(data, offset, Double.doubleToLongBits(value));
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}
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/**
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* Exception to handle buffer underruns
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*
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*@author Marc Johnson (mjohnson at apache dot org)
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*/
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public static final class BufferUnderrunException extends IOException {
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BufferUnderrunException() {
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super("buffer underrun");
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}
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}
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/**
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* get a short value from an InputStream
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*
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*@param stream the InputStream from which the short is to be read
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*@return the short (16-bit) value
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*@exception IOException will be propagated back to the caller
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*@exception BufferUnderrunException if the stream cannot provide enough bytes
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*/
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public static short readShort(InputStream stream) throws IOException, BufferUnderrunException {
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return (short) readUShort(stream);
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}
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public static int readUShort(InputStream stream) throws IOException, BufferUnderrunException {
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int ch1 = stream.read();
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int ch2 = stream.read();
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if ((ch1 | ch2) < 0) {
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throw new BufferUnderrunException();
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}
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return (ch2 << 8) + (ch1 << 0);
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}
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/**
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* get an int value from an InputStream
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*
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*@param stream the InputStream from which the int is to be read
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* @return the int (32-bit) value
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* @exception IOException will be propagated back to the caller
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* @exception BufferUnderrunException if the stream cannot provide enough bytes
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*/
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public static int readInt(InputStream stream)
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throws IOException, BufferUnderrunException {
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int ch1 = stream.read();
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int ch2 = stream.read();
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int ch3 = stream.read();
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int ch4 = stream.read();
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if ((ch1 | ch2 | ch3 | ch4) < 0) {
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throw new BufferUnderrunException();
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}
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return (ch4 << 24) + (ch3<<16) + (ch2 << 8) + (ch1 << 0);
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}
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/**
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* get a long value from an InputStream
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*
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* @param stream the InputStream from which the long is to be read
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* @return the long (64-bit) value
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* @exception IOException will be propagated back to the caller
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* @exception BufferUnderrunException if the stream cannot provide enough bytes
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*/
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public static long readLong(InputStream stream)
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throws IOException, BufferUnderrunException {
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int ch1 = stream.read();
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int ch2 = stream.read();
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int ch3 = stream.read();
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int ch4 = stream.read();
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int ch5 = stream.read();
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int ch6 = stream.read();
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int ch7 = stream.read();
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int ch8 = stream.read();
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if ((ch1 | ch2 | ch3 | ch4 | ch5 | ch6 | ch7 | ch8) < 0) {
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throw new BufferUnderrunException();
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}
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return
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((long)ch8 << 56) +
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((long)ch7 << 48) +
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((long)ch6 << 40) +
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((long)ch5 << 32) +
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((long)ch4 << 24) + // cast to long to preserve bit 31 (sign bit for ints)
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(ch3 << 16) +
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(ch2 << 8) +
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(ch1 << 0);
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}
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/**
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* Convert an 'unsigned' byte to an integer. ie, don't carry across the
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* sign.
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*
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* @param b Description of the Parameter
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* @return Description of the Return Value
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*/
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public static int ubyteToInt(byte b) {
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return b & 0xFF;
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}
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/**
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* get the unsigned value of a byte.
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*
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* @param data the byte array.
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* @param offset a starting offset into the byte array.
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* @return the unsigned value of the byte as a 32 bit integer
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*/
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public static int getUnsignedByte(byte[] data, int offset) {
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return data[offset] & 0xFF;
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}
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/**
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* Copy a portion of a byte array
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*
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* @param data the original byte array
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* @param offset Where to start copying from.
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* @param size Number of bytes to copy.
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* @return The byteArray value
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* @throws IndexOutOfBoundsException - if copying would cause access of
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* data outside array bounds.
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*/
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public static byte[] getByteArray(byte[] data, int offset, int size) {
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byte[] copy = new byte[size];
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System.arraycopy(data, offset, copy, 0, size);
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return copy;
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}
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}
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