/*
* 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.RandomAccessInput;
import org.apache.lucene.util.LongValues;
/**
* Retrieves an instance previously written by {@link DirectWriter}
* <p>
* Example usage:
* <pre class="prettyprint">
* int bitsPerValue = 100;
* IndexInput in = dir.openInput("packed", IOContext.DEFAULT);
* LongValues values = DirectReader.getInstance(in.randomAccessSlice(start, end), bitsPerValue);
* for (int i = 0; i < numValues; i++) {
* long value = values.get(i);
* }
* </pre>
* @see DirectWriter
*/
public class DirectReader {
/**
* Retrieves an instance from the specified slice written decoding
* {@code bitsPerValue} for each value
*/
public static LongValues getInstance(RandomAccessInput slice, int bitsPerValue) {
return getInstance(slice, bitsPerValue, 0);
}
/**
* Retrieves an instance from the specified {@code offset} of the given slice
* decoding {@code bitsPerValue} for each value
*/
public static LongValues getInstance(RandomAccessInput slice, int bitsPerValue, long offset) {
switch (bitsPerValue) {
case 1: return new DirectPackedReader1(slice, offset);
case 2: return new DirectPackedReader2(slice, offset);
case 4: return new DirectPackedReader4(slice, offset);
case 8: return new DirectPackedReader8(slice, offset);
case 12: return new DirectPackedReader12(slice, offset);
case 16: return new DirectPackedReader16(slice, offset);
case 20: return new DirectPackedReader20(slice, offset);
case 24: return new DirectPackedReader24(slice, offset);
case 28: return new DirectPackedReader28(slice, offset);
case 32: return new DirectPackedReader32(slice, offset);
case 40: return new DirectPackedReader40(slice, offset);
case 48: return new DirectPackedReader48(slice, offset);
case 56: return new DirectPackedReader56(slice, offset);
case 64: return new DirectPackedReader64(slice, offset);
default: throw new IllegalArgumentException("unsupported bitsPerValue: " + bitsPerValue);
}
}
static final class DirectPackedReader1 extends LongValues {
final RandomAccessInput in;
final long offset;
DirectPackedReader1(RandomAccessInput in, long offset) {
this.in = in;
this.offset = offset;
}
@Override
public long get(long index) {
try {
int shift = 7 - (int) (index & 7);
return (in.readByte(offset + (index >>> 3)) >>> shift) & 0x1;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
static final class DirectPackedReader2 extends LongValues {
final RandomAccessInput in;
final long offset;
DirectPackedReader2(RandomAccessInput in, long offset) {
this.in = in;
this.offset = offset;
}
@Override
public long get(long index) {
try {
int shift = (3 - (int)(index & 3)) << 1;
return (in.readByte(offset + (index >>> 2)) >>> shift) & 0x3;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
static final class DirectPackedReader4 extends LongValues {
final RandomAccessInput in;
final long offset;
DirectPackedReader4(RandomAccessInput in, long offset) {
this.in = in;
this.offset = offset;
}
@Override
public long get(long index) {
try {
int shift = (int) ((index + 1) & 1) << 2;
return (in.readByte(offset + (index >>> 1)) >>> shift) & 0xF;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
static final class DirectPackedReader8 extends LongValues {
final RandomAccessInput in;
final long offset;
DirectPackedReader8(RandomAccessInput in, long offset) {
this.in = in;
this.offset = offset;
}
@Override
public long get(long index) {
try {
return in.readByte(offset + index) & 0xFF;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
static final class DirectPackedReader12 extends LongValues {
final RandomAccessInput in;
final long offset;
DirectPackedReader12(RandomAccessInput in, long offset) {
this.in = in;
this.offset = offset;
}
@Override
public long get(long index) {
try {
long offset = (index * 12) >>> 3;
int shift = (int) ((index + 1) & 1) << 2;
return (in.readShort(this.offset + offset) >>> shift) & 0xFFF;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
static final class DirectPackedReader16 extends LongValues {
final RandomAccessInput in;
final long offset;
DirectPackedReader16(RandomAccessInput in, long offset) {
this.in = in;
this.offset = offset;
}
@Override
public long get(long index) {
try {
return in.readShort(offset + (index << 1)) & 0xFFFF;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
static final class DirectPackedReader20 extends LongValues {
final RandomAccessInput in;
final long offset;
DirectPackedReader20(RandomAccessInput in, long offset) {
this.in = in;
this.offset = offset;
}
@Override
public long get(long index) {
try {
long offset = (index * 20) >>> 3;
// TODO: clean this up...
int v = in.readInt(this.offset + offset) >>> 8;
int shift = (int) ((index + 1) & 1) << 2;
return (v >>> shift) & 0xFFFFF;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
static final class DirectPackedReader24 extends LongValues {
final RandomAccessInput in;
final long offset;
DirectPackedReader24(RandomAccessInput in, long offset) {
this.in = in;
this.offset = offset;
}
@Override
public long get(long index) {
try {
return in.readInt(offset + index * 3) >>> 8;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
static final class DirectPackedReader28 extends LongValues {
final RandomAccessInput in;
final long offset;
DirectPackedReader28(RandomAccessInput in, long offset) {
this.in = in;
this.offset = offset;
}
@Override
public long get(long index) {
try {
long offset = (index * 28) >>> 3;
int shift = (int) ((index + 1) & 1) << 2;
return (in.readInt(this.offset + offset) >>> shift) & 0xFFFFFFFL;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
static final class DirectPackedReader32 extends LongValues {
final RandomAccessInput in;
final long offset;
DirectPackedReader32(RandomAccessInput in, long offset) {
this.in = in;
this.offset = offset;
}
@Override
public long get(long index) {
try {
return in.readInt(this.offset + (index << 2)) & 0xFFFFFFFFL;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
static final class DirectPackedReader40 extends LongValues {
final RandomAccessInput in;
final long offset;
DirectPackedReader40(RandomAccessInput in, long offset) {
this.in = in;
this.offset = offset;
}
@Override
public long get(long index) {
try {
return in.readLong(this.offset + index * 5) >>> 24;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
static final class DirectPackedReader48 extends LongValues {
final RandomAccessInput in;
final long offset;
DirectPackedReader48(RandomAccessInput in, long offset) {
this.in = in;
this.offset = offset;
}
@Override
public long get(long index) {
try {
return in.readLong(this.offset + index * 6) >>> 16;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
static final class DirectPackedReader56 extends LongValues {
final RandomAccessInput in;
final long offset;
DirectPackedReader56(RandomAccessInput in, long offset) {
this.in = in;
this.offset = offset;
}
@Override
public long get(long index) {
try {
return in.readLong(this.offset + index * 7) >>> 8;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
static final class DirectPackedReader64 extends LongValues {
final RandomAccessInput in;
final long offset;
DirectPackedReader64(RandomAccessInput in, long offset) {
this.in = in;
this.offset = offset;
}
@Override
public long get(long index) {
try {
return in.readLong(offset + (index << 3));
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
}