| using J2N.Numerics; |
| using System; |
| using System.IO; |
| using System.Runtime.CompilerServices; |
| |
| namespace Lucene.Net.Util.Packed |
| { |
| /* |
| * 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. |
| */ |
| |
| using IndexInput = Lucene.Net.Store.IndexInput; |
| |
| /* Reads directly from disk on each get */ |
| |
| internal class DirectPackedReader : PackedInt32s.ReaderImpl |
| { |
| private readonly IndexInput @in; |
| private readonly long startPointer; |
| private readonly long valueMask; |
| |
| public DirectPackedReader(int bitsPerValue, int valueCount, IndexInput @in) |
| : base(valueCount, bitsPerValue) |
| { |
| this.@in = @in; |
| |
| startPointer = @in.GetFilePointer(); |
| if (bitsPerValue == 64) |
| { |
| valueMask = -1L; |
| } |
| else |
| { |
| valueMask = (1L << bitsPerValue) - 1; |
| } |
| } |
| |
| public override long Get(int index) |
| { |
| long majorBitPos = (long)index * m_bitsPerValue; |
| long elementPos = majorBitPos.TripleShift(3); |
| try |
| { |
| @in.Seek(startPointer + elementPos); |
| |
| int bitPos = (int)(majorBitPos & 7); |
| // round up bits to a multiple of 8 to find total bytes needed to read |
| int roundedBits = ((bitPos + m_bitsPerValue + 7) & ~7); |
| // the number of extra bits read at the end to shift out |
| int shiftRightBits = roundedBits - bitPos - m_bitsPerValue; |
| |
| long rawValue; |
| switch (roundedBits.TripleShift(3)) |
| { |
| case 1: |
| rawValue = @in.ReadByte(); |
| break; |
| |
| case 2: |
| rawValue = @in.ReadInt16(); |
| break; |
| |
| case 3: |
| rawValue = ((long)@in.ReadInt16() << 8) | (@in.ReadByte() & 0xFFL); |
| break; |
| |
| case 4: |
| rawValue = @in.ReadInt32(); |
| break; |
| |
| case 5: |
| rawValue = ((long)@in.ReadInt32() << 8) | (@in.ReadByte() & 0xFFL); |
| break; |
| |
| case 6: |
| rawValue = ((long)@in.ReadInt32() << 16) | (@in.ReadInt16() & 0xFFFFL); |
| break; |
| |
| case 7: |
| rawValue = ((long)@in.ReadInt32() << 24) | ((@in.ReadInt16() & 0xFFFFL) << 8) | (@in.ReadByte() & 0xFFL); |
| break; |
| |
| case 8: |
| rawValue = @in.ReadInt64(); |
| 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.ReadInt64() << (8 - shiftRightBits)) | (((uint)(@in.ReadByte() & 0xFFL) >> shiftRightBits)); |
| shiftRightBits = 0; |
| break; |
| |
| default: |
| throw new InvalidOperationException("bitsPerValue too large: " + m_bitsPerValue); |
| } |
| return (rawValue.TripleShift(shiftRightBits)) & valueMask; |
| } |
| catch (IOException ioe) |
| { |
| throw new InvalidOperationException("failed", ioe); |
| } |
| } |
| |
| [MethodImpl(MethodImplOptions.AggressiveInlining)] |
| public override long RamBytesUsed() |
| { |
| return 0; |
| } |
| } |
| } |