| /* |
| * 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 org.apache.lucene.store.IndexInput; |
| |
| import java.io.IOException; |
| |
| /* Reads directly from disk on each get */ |
| // just for back compat, use DirectReader/DirectWriter for more efficient impl |
| class DirectPackedReader extends PackedInts.ReaderImpl { |
| final IndexInput in; |
| final int bitsPerValue; |
| final long startPointer; |
| final long valueMask; |
| |
| DirectPackedReader(int bitsPerValue, int valueCount, IndexInput in) { |
| super(valueCount); |
| this.in = in; |
| this.bitsPerValue = bitsPerValue; |
| |
| startPointer = in.getFilePointer(); |
| if (bitsPerValue == 64) { |
| valueMask = -1L; |
| } else { |
| valueMask = (1L << bitsPerValue) - 1; |
| } |
| } |
| |
| @Override |
| public long get(int index) { |
| final long majorBitPos = (long)index * bitsPerValue; |
| final long elementPos = majorBitPos >>> 3; |
| try { |
| in.seek(startPointer + elementPos); |
| |
| final int bitPos = (int) (majorBitPos & 7); |
| // round up bits to a multiple of 8 to find total bytes needed to read |
| final int roundedBits = ((bitPos + bitsPerValue + 7) & ~7); |
| // the number of extra bits read at the end to shift out |
| int shiftRightBits = roundedBits - bitPos - bitsPerValue; |
| |
| long rawValue; |
| switch (roundedBits >>> 3) { |
| case 1: |
| rawValue = in.readByte(); |
| break; |
| case 2: |
| rawValue = in.readShort(); |
| break; |
| case 3: |
| rawValue = ((long)in.readShort() << 8) | (in.readByte() & 0xFFL); |
| break; |
| case 4: |
| rawValue = in.readInt(); |
| break; |
| case 5: |
| rawValue = ((long)in.readInt() << 8) | (in.readByte() & 0xFFL); |
| break; |
| case 6: |
| rawValue = ((long)in.readInt() << 16) | (in.readShort() & 0xFFFFL); |
| break; |
| case 7: |
| rawValue = ((long)in.readInt() << 24) | ((in.readShort() & 0xFFFFL) << 8) | (in.readByte() & 0xFFL); |
| break; |
| case 8: |
| rawValue = in.readLong(); |
| break; |
| case 9: |
| // We must be very careful not to shift out relevant bits. So we account for right shift |
| // we would normally do on return here, and reset it. |
| rawValue = (in.readLong() << (8 - shiftRightBits)) | ((in.readByte() & 0xFFL) >>> shiftRightBits); |
| shiftRightBits = 0; |
| break; |
| default: |
| throw new AssertionError("bitsPerValue too large: " + bitsPerValue); |
| } |
| return (rawValue >>> shiftRightBits) & valueMask; |
| |
| } catch (IOException ioe) { |
| throw new RuntimeException(ioe); |
| } |
| } |
| |
| @Override |
| public long ramBytesUsed() { |
| return 0; |
| } |
| } |