org.apache.activemq.artemis.shaded.io.netty.handler.codec.compression.Bzip2BitReader Maven / Gradle / Ivy
/*
* 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 org.apache.activemq.artemis.shaded.io.netty.handler.codec.compression;
import org.apache.activemq.artemis.shaded.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);
}
}