| /* |
| * 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.lucene.util.packed; |
| |
| |
| import java.io.IOException; |
| |
| import org.apache.lucene.store.DataInput; |
| |
| /** |
| * A {@link DataInput} wrapper to read unaligned, variable-length packed |
| * integers. This API is much slower than the {@link PackedInts} fixed-length |
| * API but can be convenient to save space. |
| * @see PackedDataOutput |
| * @lucene.internal |
| */ |
| public final class PackedDataInput { |
| |
| final DataInput in; |
| long current; |
| int remainingBits; |
| |
| /** |
| * Create a new instance that wraps <code>in</code>. |
| */ |
| public PackedDataInput(DataInput in) { |
| this.in = in; |
| skipToNextByte(); |
| } |
| |
| /** |
| * Read the next long using exactly <code>bitsPerValue</code> bits. |
| */ |
| public long readLong(int bitsPerValue) throws IOException { |
| assert bitsPerValue > 0 && bitsPerValue <= 64 : bitsPerValue; |
| long r = 0; |
| while (bitsPerValue > 0) { |
| if (remainingBits == 0) { |
| current = in.readByte() & 0xFF; |
| remainingBits = 8; |
| } |
| final int bits = Math.min(bitsPerValue, remainingBits); |
| r = (r << bits) | ((current >>> (remainingBits - bits)) & ((1L << bits) - 1)); |
| bitsPerValue -= bits; |
| remainingBits -= bits; |
| } |
| return r; |
| } |
| |
| /** |
| * If there are pending bits (at most 7), they will be ignored and the next |
| * value will be read starting at the next byte. |
| */ |
| public void skipToNextByte() { |
| remainingBits = 0; |
| } |
| |
| } |