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/*
* Copyright 2016 - 2018 Anton Tananaev (anton@traccar.org)
*
* Licensed 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.traccar.helper;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
public class BitBuffer {
private final ByteBuf buffer;
private int writeByte;
private int writeCount;
private int readByte;
private int readCount;
public BitBuffer() {
buffer = Unpooled.buffer();
}
public BitBuffer(ByteBuf buffer) {
this.buffer = buffer;
}
public void writeEncoded(byte[] bytes) {
for (byte b : bytes) {
b -= 48;
if (b > 40) {
b -= 8;
}
write(b);
}
}
public void write(int b) {
if (writeCount == 0) {
writeByte |= b;
writeCount = 6;
} else {
int remaining = 8 - writeCount;
writeByte <<= remaining;
writeByte |= b >> (6 - remaining);
buffer.writeByte(writeByte);
writeByte = b & ((1 << (6 - remaining)) - 1);
writeCount = 6 - remaining;
}
}
public int readUnsigned(int length) {
int result = 0;
while (length > 0) {
if (readCount == 0) {
readByte = buffer.readUnsignedByte();
readCount = 8;
}
if (readCount >= length) {
result <<= length;
result |= readByte >> (readCount - length);
readByte &= (1 << (readCount - length)) - 1;
readCount -= length;
length = 0;
} else {
result <<= readCount;
result |= readByte;
length -= readCount;
readByte = 0;
readCount = 0;
}
}
return result;
}
public int readSigned(int length) {
int result = readUnsigned(length);
int signBit = 1 << (length - 1);
if ((result & signBit) == 0) {
return result;
} else {
result &= signBit - 1;
result += ~(signBit - 1);
return result;
}
}
}
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