org.fusesource.hawtbuf.AbstractVarIntSupport Maven / Gradle / Ivy
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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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