io.netty.handler.codec.compression.Bzip2BitReader Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
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/*
* Copyright 2014 The Netty Project
*
* The Netty Project 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:
*
* https://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 io.netty.handler.codec.compression;
import io.netty.buffer.ByteBuf;
/**
* An bit reader that allows the reading of single bit booleans, bit strings of
* arbitrary length (up to 32 bits), and bit aligned 32-bit integers. A single byte
* at a time is read from the {@link ByteBuf} when more bits are required.
*/
class Bzip2BitReader {
/**
* Maximum count of possible readable bytes to check.
*/
private static final int MAX_COUNT_OF_READABLE_BYTES = Integer.MAX_VALUE >>> 3;
/**
* The {@link ByteBuf} from which to read data.
*/
private ByteBuf in;
/**
* A buffer of bits read from the input stream that have not yet been returned.
*/
private long bitBuffer;
/**
* The number of bits currently buffered in {@link #bitBuffer}.
*/
private int bitCount;
/**
* Set the {@link ByteBuf} from which to read data.
*/
void setByteBuf(ByteBuf in) {
this.in = in;
}
/**
* Reads up to 32 bits from the {@link ByteBuf}.
* @param count The number of bits to read (maximum {@code 32} as a size of {@code int})
* @return The bits requested, right-aligned within the integer
*/
int readBits(final int count) {
if (count < 0 || count > 32) {
throw new IllegalArgumentException("count: " + count + " (expected: 0-32 )");
}
int bitCount = this.bitCount;
long bitBuffer = this.bitBuffer;
if (bitCount < count) {
long readData;
int offset;
switch (in.readableBytes()) {
case 1: {
readData = in.readUnsignedByte();
offset = 8;
break;
}
case 2: {
readData = in.readUnsignedShort();
offset = 16;
break;
}
case 3: {
readData = in.readUnsignedMedium();
offset = 24;
break;
}
default: {
readData = in.readUnsignedInt();
offset = 32;
break;
}
}
bitBuffer = bitBuffer << offset | readData;
bitCount += offset;
this.bitBuffer = bitBuffer;
}
this.bitCount = bitCount -= count;
return (int) (bitBuffer >>> bitCount & (count != 32 ? (1 << count) - 1 : 0xFFFFFFFFL));
}
/**
* Reads a single bit from the {@link ByteBuf}.
* @return {@code true} if the bit read was {@code 1}, otherwise {@code false}
*/
boolean readBoolean() {
return readBits(1) != 0;
}
/**
* Reads 32 bits of input as an integer.
* @return The integer read
*/
int readInt() {
return readBits(32);
}
/**
* Refill the {@link ByteBuf} by one byte.
*/
void refill() {
int readData = in.readUnsignedByte();
bitBuffer = bitBuffer << 8 | readData;
bitCount += 8;
}
/**
* Checks that at least one bit is available for reading.
* @return {@code true} if one bit is available for reading, otherwise {@code false}
*/
boolean isReadable() {
return bitCount > 0 || in.isReadable();
}
/**
* Checks that the specified number of bits available for reading.
* @param count The number of bits to check
* @return {@code true} if {@code count} bits are available for reading, otherwise {@code false}
*/
boolean hasReadableBits(int count) {
if (count < 0) {
throw new IllegalArgumentException("count: " + count + " (expected value greater than 0)");
}
return bitCount >= count || (in.readableBytes() << 3 & Integer.MAX_VALUE) >= count - bitCount;
}
/**
* Checks that the specified number of bytes available for reading.
* @param count The number of bytes to check
* @return {@code true} if {@code count} bytes are available for reading, otherwise {@code false}
*/
boolean hasReadableBytes(int count) {
if (count < 0 || count > MAX_COUNT_OF_READABLE_BYTES) {
throw new IllegalArgumentException("count: " + count
+ " (expected: 0-" + MAX_COUNT_OF_READABLE_BYTES + ')');
}
return hasReadableBits(count << 3);
}
}