121 lines
3.3 KiB
Java
121 lines
3.3 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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/**
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* Adapts a plain byte array to {@link LittleEndianInput}
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*
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*
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* @author Josh Micich
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*/
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public final class LittleEndianByteArrayInputStream implements LittleEndianInput {
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private final byte[] _buf;
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private final int _endIndex;
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private int _readIndex;
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public LittleEndianByteArrayInputStream(byte[] buf, int startOffset, int maxReadLen) {
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_buf = buf;
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_readIndex = startOffset;
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_endIndex = startOffset + maxReadLen;
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}
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public LittleEndianByteArrayInputStream(byte[] buf, int startOffset) {
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this(buf, startOffset, buf.length - startOffset);
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}
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public LittleEndianByteArrayInputStream(byte[] buf) {
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this(buf, 0, buf.length);
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}
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public int available() {
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return _endIndex - _readIndex;
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}
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private void checkPosition(int i) {
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if (i > _endIndex - _readIndex) {
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throw new RuntimeException("Buffer overrun");
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}
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}
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public int getReadIndex() {
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return _readIndex;
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}
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public byte readByte() {
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checkPosition(1);
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return _buf[_readIndex++];
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}
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public int readInt() {
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checkPosition(4);
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int i = _readIndex;
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int b0 = _buf[i++] & 0xFF;
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int b1 = _buf[i++] & 0xFF;
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int b2 = _buf[i++] & 0xFF;
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int b3 = _buf[i++] & 0xFF;
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_readIndex = i;
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return (b3 << 24) + (b2 << 16) + (b1 << 8) + (b0 << 0);
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}
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public long readLong() {
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checkPosition(8);
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int i = _readIndex;
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int b0 = _buf[i++] & 0xFF;
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int b1 = _buf[i++] & 0xFF;
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int b2 = _buf[i++] & 0xFF;
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int b3 = _buf[i++] & 0xFF;
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int b4 = _buf[i++] & 0xFF;
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int b5 = _buf[i++] & 0xFF;
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int b6 = _buf[i++] & 0xFF;
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int b7 = _buf[i++] & 0xFF;
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_readIndex = i;
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return (((long)b7 << 56) +
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((long)b6 << 48) +
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((long)b5 << 40) +
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((long)b4 << 32) +
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((long)b3 << 24) +
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(b2 << 16) +
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(b1 << 8) +
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(b0 << 0));
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}
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public short readShort() {
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return (short)readUShort();
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}
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public int readUByte() {
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checkPosition(1);
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return _buf[_readIndex++] & 0xFF;
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}
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public int readUShort() {
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checkPosition(2);
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int i = _readIndex;
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int b0 = _buf[i++] & 0xFF;
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int b1 = _buf[i++] & 0xFF;
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_readIndex = i;
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return (b1 << 8) + (b0 << 0);
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}
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public void readFully(byte[] buf, int off, int len) {
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checkPosition(len);
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System.arraycopy(_buf, _readIndex, _buf, off, len);
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_readIndex+=len;
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}
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public void readFully(byte[] buf) {
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readFully(buf, 0, buf.length);
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}
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public double readDouble() {
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return Double.longBitsToDouble(readLong());
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}
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}
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