| /* |
| * 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.giraph.utils; |
| |
| /** |
| * This Code is adapted from main/java/org/apache/mahout/math/Varint.java |
| * |
| * 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. |
| */ |
| |
| import java.io.DataInput; |
| import java.io.DataOutput; |
| import java.io.IOException; |
| |
| /** |
| * <p> |
| * Encodes signed and unsigned values using a common variable-length scheme, |
| * found for example in <a |
| * href="http://code.google.com/apis/protocolbuffers/docs/encoding.html"> |
| * Google's Protocol Buffers</a>. It uses fewer bytes to encode smaller values, |
| * but will use slightly more bytes to encode large values. |
| * </p> |
| * <p/> |
| * <p> |
| * Signed values are further encoded using so-called zig-zag encoding in order |
| * to make them "compatible" with variable-length encoding. |
| * </p> |
| */ |
| public final class Varint { |
| |
| /** |
| * private constructor |
| */ |
| private Varint() { |
| } |
| |
| /** |
| * Encodes a value using the variable-length encoding from <a |
| * href="http://code.google.com/apis/protocolbuffers/docs/encoding.html"> |
| * Google Protocol Buffers</a>. |
| * |
| * @param value to encode |
| * @param out to write bytes to |
| * @throws IOException |
| * if {@link DataOutput} throws {@link IOException} |
| */ |
| private static void writeVarLong( |
| long value, |
| DataOutput out |
| ) throws IOException { |
| while (true) { |
| int bits = ((int) value) & 0x7f; |
| value >>>= 7; |
| if (value == 0) { |
| out.writeByte((byte) bits); |
| return; |
| } |
| out.writeByte((byte) (bits | 0x80)); |
| } |
| } |
| |
| /** |
| * Encodes a value using the variable-length encoding from <a |
| * href="http://code.google.com/apis/protocolbuffers/docs/encoding.html"> |
| * Google Protocol Buffers</a>. |
| * |
| * @param value to encode |
| * @param out to write bytes to |
| * @throws IOException |
| * if {@link DataOutput} throws {@link IOException} |
| */ |
| public static void writeUnsignedVarLong( |
| long value, |
| DataOutput out |
| ) throws IOException { |
| if (value < 0) { |
| throw new IllegalStateException( |
| "Negative value passed into writeUnsignedVarLong - " + value); |
| } |
| writeVarLong(value, out); |
| } |
| |
| /** |
| * Zig-zag encoding for signed longs |
| * |
| * @param value to encode |
| * @param out to write bytes to |
| * @throws IOException |
| * if {@link DataOutput} throws {@link IOException} |
| */ |
| public static void writeSignedVarLong( |
| long value, |
| DataOutput out |
| ) throws IOException { |
| writeVarLong((value << 1) ^ (value >> 63), out); |
| } |
| |
| /** |
| * @see #writeVarLong(long, DataOutput) |
| * @param value to encode |
| * @param out to write bytes to |
| * @throws IOException |
| */ |
| private static void writeVarInt( |
| int value, |
| DataOutput out |
| ) throws IOException { |
| while (true) { |
| int bits = value & 0x7f; |
| value >>>= 7; |
| if (value == 0) { |
| out.writeByte((byte) bits); |
| return; |
| } |
| out.writeByte((byte) (bits | 0x80)); |
| } |
| } |
| |
| /** |
| * @see #writeVarLong(long, DataOutput) |
| * @param value to encode |
| * @param out to write bytes to |
| * @throws IOException |
| */ |
| public static void writeUnsignedVarInt( |
| int value, |
| DataOutput out |
| ) throws IOException { |
| if (value < 0) { |
| throw new IllegalStateException( |
| "Negative value passed into writeUnsignedVarInt - " + value); |
| } |
| writeVarInt(value, out); |
| } |
| |
| /** |
| * Zig-zag encoding for signed ints |
| * |
| * @see #writeUnsignedVarInt(int, DataOutput) |
| * @param value to encode |
| * @param out to write bytes to |
| * @throws IOException |
| */ |
| public static void writeSignedVarInt( |
| int value, |
| DataOutput out |
| ) throws IOException { |
| writeVarInt((value << 1) ^ (value >> 31), out); |
| } |
| |
| /** |
| * @param in to read bytes from |
| * @return decode value |
| * @throws IOException |
| * if {@link DataInput} throws {@link IOException} |
| */ |
| public static long readUnsignedVarLong(DataInput in) throws IOException { |
| long tmp; |
| // CHECKSTYLE: stop InnerAssignment |
| if ((tmp = in.readByte()) >= 0) { |
| return tmp; |
| } |
| long result = tmp & 0x7f; |
| if ((tmp = in.readByte()) >= 0) { |
| result |= tmp << 7; |
| } else { |
| result |= (tmp & 0x7f) << 7; |
| if ((tmp = in.readByte()) >= 0) { |
| result |= tmp << 14; |
| } else { |
| result |= (tmp & 0x7f) << 14; |
| if ((tmp = in.readByte()) >= 0) { |
| result |= tmp << 21; |
| } else { |
| result |= (tmp & 0x7f) << 21; |
| if ((tmp = in.readByte()) >= 0) { |
| result |= tmp << 28; |
| } else { |
| result |= (tmp & 0x7f) << 28; |
| if ((tmp = in.readByte()) >= 0) { |
| result |= tmp << 35; |
| } else { |
| result |= (tmp & 0x7f) << 35; |
| if ((tmp = in.readByte()) >= 0) { |
| result |= tmp << 42; |
| } else { |
| result |= (tmp & 0x7f) << 42; |
| if ((tmp = in.readByte()) >= 0) { |
| result |= tmp << 49; |
| } else { |
| result |= (tmp & 0x7f) << 49; |
| if ((tmp = in.readByte()) >= 0) { |
| result |= tmp << 56; |
| } else { |
| result |= (tmp & 0x7f) << 56; |
| result |= ((long) in.readByte()) << 63; |
| } |
| } |
| } |
| } |
| } |
| } |
| } |
| } |
| // CHECKSTYLE: resume InnerAssignment |
| return result; |
| } |
| |
| /** |
| * @param in to read bytes from |
| * @return decode value |
| * @throws IOException |
| * if {@link DataInput} throws {@link IOException} |
| */ |
| public static long readSignedVarLong(DataInput in) throws IOException { |
| long raw = readUnsignedVarLong(in); |
| long temp = (((raw << 63) >> 63) ^ raw) >> 1; |
| return temp ^ (raw & (1L << 63)); |
| } |
| |
| /** |
| * @throws IOException |
| * if {@link DataInput} throws {@link IOException} |
| * @param in to read bytes from |
| * @return decode value |
| */ |
| public static int readUnsignedVarInt(DataInput in) throws IOException { |
| int tmp; |
| // CHECKSTYLE: stop InnerAssignment |
| if ((tmp = in.readByte()) >= 0) { |
| return tmp; |
| } |
| int result = tmp & 0x7f; |
| if ((tmp = in.readByte()) >= 0) { |
| result |= tmp << 7; |
| } else { |
| result |= (tmp & 0x7f) << 7; |
| if ((tmp = in.readByte()) >= 0) { |
| result |= tmp << 14; |
| } else { |
| result |= (tmp & 0x7f) << 14; |
| if ((tmp = in.readByte()) >= 0) { |
| result |= tmp << 21; |
| } else { |
| result |= (tmp & 0x7f) << 21; |
| result |= (in.readByte()) << 28; |
| } |
| } |
| } |
| // CHECKSTYLE: resume InnerAssignment |
| return result; |
| } |
| |
| /** |
| * @throws IOException |
| * if {@link DataInput} throws {@link IOException} |
| * @param in to read bytes from |
| * @return decode value |
| */ |
| public static int readSignedVarInt(DataInput in) throws IOException { |
| int raw = readUnsignedVarInt(in); |
| int temp = (((raw << 31) >> 31) ^ raw) >> 1; |
| return temp ^ (raw & (1 << 31)); |
| } |
| |
| /** |
| * Simulation for what will happen when writing an unsigned long value |
| * as varlong. |
| * @param value to consider |
| * @return the number of bytes needed to write value. |
| * @throws IOException |
| */ |
| public static long sizeOfUnsignedVarLong(long value) throws IOException { |
| int result = 0; |
| do { |
| result++; |
| value >>>= 7; |
| } while (value != 0); |
| return result; |
| } |
| |
| /** |
| * Simulation for what will happen when writing a signed long value |
| * as varlong. |
| * @param value to consider |
| * @return the number of bytes needed to write value. |
| * @throws IOException |
| */ |
| public static long sizeOfSignedVarLong(long value) throws IOException { |
| return sizeOfUnsignedVarLong((value << 1) ^ (value >> 63)); |
| } |
| |
| /** |
| * Simulation for what will happen when writing an unsigned int value |
| * as varint. |
| * @param value to consider |
| * @return the number of bytes needed to write value. |
| * @throws IOException |
| */ |
| public static int sizeOfUnsignedVarInt(int value) throws IOException { |
| int cnt = 0; |
| do { |
| cnt++; |
| value >>>= 7; |
| } while (value != 0); |
| return cnt; |
| } |
| |
| /** |
| * Simulation for what will happen when writing a signed int value |
| * as varint. |
| * @param value to consider |
| * @return the number of bytes needed to write value. |
| * @throws IOException |
| */ |
| public static int sizeOfSignedVarInt(int value) throws IOException { |
| return sizeOfUnsignedVarInt((value << 1) ^ (value >> 31)); |
| } |
| |
| } |