| /* |
| * 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.imaging.common; |
| |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| public class BitInputStream extends InputStream implements BinaryConstants |
| { |
| |
| private final InputStream is; |
| private final int byteOrder; |
| |
| public BitInputStream(InputStream is, int byteOrder) |
| { |
| this.is = is; |
| this.byteOrder = byteOrder; |
| // super(is); |
| } |
| |
| @Override |
| public int read() throws IOException |
| { |
| if (cacheBitsRemaining > 0) |
| throw new IOException("BitInputStream: incomplete bit read"); |
| return is.read(); |
| } |
| |
| private int cache; |
| private int cacheBitsRemaining = 0; |
| private long bytes_read = 0; |
| |
| public final int readBits(int count) throws IOException |
| { |
| if (count < 8) |
| { |
| if (cacheBitsRemaining == 0) |
| { |
| // fill cache |
| cache = is.read(); |
| cacheBitsRemaining = 8; |
| bytes_read++; |
| } |
| if (count > cacheBitsRemaining) |
| throw new IOException( |
| "BitInputStream: can't read bit fields across bytes"); |
| |
| // int bits_to_shift = cache_bits_remaining - count; |
| cacheBitsRemaining -= count; |
| int bits = cache >> cacheBitsRemaining; |
| |
| switch (count) |
| { |
| case 1 : |
| return bits & 1; |
| case 2 : |
| return bits & 3; |
| case 3 : |
| return bits & 7; |
| case 4 : |
| return bits & 15; |
| case 5 : |
| return bits & 31; |
| case 6 : |
| return bits & 63; |
| case 7 : |
| return bits & 127; |
| } |
| |
| } |
| if (cacheBitsRemaining > 0) |
| throw new IOException("BitInputStream: incomplete bit read"); |
| |
| if (count == 8) |
| { |
| bytes_read++; |
| return is.read(); |
| } |
| |
| /** |
| * Taking default order of the Tiff to be |
| * Little Endian and reversing the bytes in the end |
| * if its Big Endian.This is done because majority (may be all) |
| * of the files will be of Little Endian. |
| */ |
| if(byteOrder == BYTE_ORDER_BIG_ENDIAN) { |
| if (count == 16) |
| { |
| bytes_read += 2; |
| return (is.read() << 8) | (is.read() << 0); |
| } |
| |
| if (count == 24) |
| { |
| bytes_read += 3; |
| return (is.read() << 16) | (is.read() << 8) | (is.read() << 0); |
| } |
| |
| if (count == 32) |
| { |
| bytes_read += 4; |
| return (is.read() << 24) | (is.read() << 16) | (is.read() << 8) |
| | (is.read() << 0); |
| } |
| } |
| else |
| { |
| if(count == 16) |
| { |
| bytes_read +=2; |
| return ((is.read() << 0) | (is.read() << 8)); |
| } |
| |
| if(count == 24) |
| { |
| bytes_read += 3; |
| return ((is.read() << 0) | (is.read() << 8) | (is.read() << 16)); |
| } |
| |
| if(count == 32) |
| { |
| bytes_read += 4; |
| return ((is.read() << 0) | (is.read() << 8) | (is.read() << 16) | (is.read() << 24)); |
| } |
| } |
| |
| throw new IOException("BitInputStream: unknown error"); |
| } |
| |
| public void flushCache() |
| { |
| cacheBitsRemaining = 0; |
| } |
| |
| public long getBytesRead() |
| { |
| return bytes_read; |
| } |
| } |