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/**
 * Copyright (C) 2010, FuseSource Corp.  All rights reserved.
 */
package org.fusesource.hawtbuf;

import java.io.IOException;
import java.net.ProtocolException;

/**
 * 

*

* * @author Hiram Chirino */ abstract public class AbstractVarIntSupport { abstract protected byte readByte() throws IOException; abstract protected void writeByte(int value) throws IOException; /** * Read a raw Varint from the stream. If larger than 32 bits, discard the * upper bits. */ public int readVarInt() throws IOException { byte tmp = readByte(); if (tmp >= 0) { return tmp; } int result = tmp & 0x7f; if ((tmp = readByte()) >= 0) { result |= tmp << 7; } else { result |= (tmp & 0x7f) << 7; if ((tmp = readByte()) >= 0) { result |= tmp << 14; } else { result |= (tmp & 0x7f) << 14; if ((tmp = readByte()) >= 0) { result |= tmp << 21; } else { result |= (tmp & 0x7f) << 21; result |= (tmp = readByte()) << 28; if (tmp < 0) { // Discard upper 32 bits. for (int i = 0; i < 5; i++) { if (readByte() >= 0) return result; } throw new ProtocolException("Encountered a malformed variable int"); } } } } return result; } /** Read a raw Varint from the stream. */ public long readVarLong() throws IOException { int shift = 0; long result = 0; while (shift < 64) { byte b = readByte(); result |= (long) (b & 0x7F) << shift; if ((b & 0x80) == 0) return result; shift += 7; } throw new ProtocolException("Encountered a malformed variable int"); } /** Read an {@code sint32} field value from the stream. */ public int readVarSignedInt() throws IOException { return decodeZigZag32(readVarInt()); } /** Read an {@code sint64} field value from the stream. */ public long readVarSignedLong() throws IOException { return decodeZigZag64(readVarLong()); } /** * Encode and write a varint. {@code value} is treated as unsigned, so it * won't be sign-extended if negative. */ public void writeVarInt(int value) throws IOException { while (true) { if ((value & ~0x7F) == 0) { writeByte(value); return; } else { writeByte((value & 0x7F) | 0x80); value >>>= 7; } } } /** Encode and write a varint. */ public void writeVarLong(long value) throws IOException { while (true) { if ((value & ~0x7FL) == 0) { writeByte((int) value); return; } else { writeByte(((int) value & 0x7F) | 0x80); value >>>= 7; } } } public void writeVarSignedInt(int value) throws IOException { writeVarInt(encodeZigZag32(value)); } public void writeVarSignedLong(long value) throws IOException { writeVarLong(encodeZigZag64(value)); } private static int decodeZigZag32(int n) { return (n >>> 1) ^ -(n & 1); } private static long decodeZigZag64(long n) { return (n >>> 1) ^ -(n & 1); } private static int encodeZigZag32(int n) { return (n << 1) ^ (n >> 31); } private static long encodeZigZag64(long n) { return (n << 1) ^ (n >> 63); } /** * Compute the number of bytes that would be needed to encode a varint. * {@code value} is treated as unsigned, so it won't be sign-extended if * negative. */ public static int computeVarIntSize(int value) { if ((value & (0xffffffff << 7)) == 0) return 1; if ((value & (0xffffffff << 14)) == 0) return 2; if ((value & (0xffffffff << 21)) == 0) return 3; if ((value & (0xffffffff << 28)) == 0) return 4; return 5; } /** Compute the number of bytes that would be needed to encode a varint. */ public static int computeVarLongSize(long value) { if ((value & (0xffffffffffffffffL << 7)) == 0) return 1; if ((value & (0xffffffffffffffffL << 14)) == 0) return 2; if ((value & (0xffffffffffffffffL << 21)) == 0) return 3; if ((value & (0xffffffffffffffffL << 28)) == 0) return 4; if ((value & (0xffffffffffffffffL << 35)) == 0) return 5; if ((value & (0xffffffffffffffffL << 42)) == 0) return 6; if ((value & (0xffffffffffffffffL << 49)) == 0) return 7; if ((value & (0xffffffffffffffffL << 56)) == 0) return 8; if ((value & (0xffffffffffffffffL << 63)) == 0) return 9; return 10; } /** * Compute the number of bytes that would be needed to encode a signed varint. */ public static int computeVarSignedIntSize(int value) { return computeVarIntSize(encodeZigZag32(value)); } /** * Compute the number of bytes that would be needed to encode a signed varint. */ public static int computeVarSignedLongSize(long value) { return computeVarLongSize(encodeZigZag64(value)); } }




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