NB.java
/*
* Copyright (C) 2008, 2015 Shawn O. Pearce <spearce@spearce.org> and others
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.util;
/**
* Conversion utilities for network byte order handling.
*/
public final class NB {
/**
* Compare a 32 bit unsigned integer stored in a 32 bit signed integer.
* <p>
* This function performs an unsigned compare operation, even though Java
* does not natively support unsigned integer values. Negative numbers are
* treated as larger than positive ones.
*
* @param a
* the first value to compare.
* @param b
* the second value to compare.
* @return < 0 if a < b; 0 if a == b; > 0 if a > b.
*/
public static int compareUInt32(final int a, final int b) {
final int cmp = (a >>> 1) - (b >>> 1);
if (cmp != 0)
return cmp;
return (a & 1) - (b & 1);
}
/**
* Compare a 64 bit unsigned integer stored in a 64 bit signed integer.
* <p>
* This function performs an unsigned compare operation, even though Java
* does not natively support unsigned integer values. Negative numbers are
* treated as larger than positive ones.
*
* @param a
* the first value to compare.
* @param b
* the second value to compare.
* @return < 0 if a < b; 0 if a == b; > 0 if a > b.
* @since 4.3
*/
public static int compareUInt64(final long a, final long b) {
long cmp = (a >>> 1) - (b >>> 1);
if (cmp > 0) {
return 1;
} else if (cmp < 0) {
return -1;
}
cmp = ((a & 1) - (b & 1));
if (cmp > 0) {
return 1;
} else if (cmp < 0) {
return -1;
} else {
return 0;
}
}
/**
* Convert sequence of 2 bytes (network byte order) into unsigned value.
*
* @param intbuf
* buffer to acquire the 2 bytes of data from.
* @param offset
* position within the buffer to begin reading from. This
* position and the next byte after it (for a total of 2 bytes)
* will be read.
* @return unsigned integer value that matches the 16 bits read.
*/
public static int decodeUInt16(final byte[] intbuf, final int offset) {
int r = (intbuf[offset] & 0xff) << 8;
return r | (intbuf[offset + 1] & 0xff);
}
/**
* Convert sequence of 3 bytes (network byte order) into unsigned value.
*
* @param intbuf
* buffer to acquire the 3 bytes of data from.
* @param offset
* position within the buffer to begin reading from. This
* position and the next 2 bytes after it (for a total of 3
* bytes) will be read.
* @return signed integer value that matches the 24 bits read.
* @since 4.9
*/
public static int decodeUInt24(byte[] intbuf, int offset) {
int r = (intbuf[offset] & 0xff) << 8;
r |= intbuf[offset + 1] & 0xff;
return (r << 8) | (intbuf[offset + 2] & 0xff);
}
/**
* Convert sequence of 4 bytes (network byte order) into signed value.
*
* @param intbuf
* buffer to acquire the 4 bytes of data from.
* @param offset
* position within the buffer to begin reading from. This
* position and the next 3 bytes after it (for a total of 4
* bytes) will be read.
* @return signed integer value that matches the 32 bits read.
*/
public static int decodeInt32(final byte[] intbuf, final int offset) {
int r = intbuf[offset] << 8;
r |= intbuf[offset + 1] & 0xff;
r <<= 8;
r |= intbuf[offset + 2] & 0xff;
return (r << 8) | (intbuf[offset + 3] & 0xff);
}
/**
* Convert sequence of 8 bytes (network byte order) into signed value.
*
* @param intbuf
* buffer to acquire the 8 bytes of data from.
* @param offset
* position within the buffer to begin reading from. This
* position and the next 7 bytes after it (for a total of 8
* bytes) will be read.
* @return signed integer value that matches the 64 bits read.
* @since 3.0
*/
public static long decodeInt64(final byte[] intbuf, final int offset) {
long r = intbuf[offset] << 8;
r |= intbuf[offset + 1] & 0xff;
r <<= 8;
r |= intbuf[offset + 2] & 0xff;
r <<= 8;
r |= intbuf[offset + 3] & 0xff;
r <<= 8;
r |= intbuf[offset + 4] & 0xff;
r <<= 8;
r |= intbuf[offset + 5] & 0xff;
r <<= 8;
r |= intbuf[offset + 6] & 0xff;
return (r << 8) | (intbuf[offset + 7] & 0xff);
}
/**
* Convert sequence of 4 bytes (network byte order) into unsigned value.
*
* @param intbuf
* buffer to acquire the 4 bytes of data from.
* @param offset
* position within the buffer to begin reading from. This
* position and the next 3 bytes after it (for a total of 4
* bytes) will be read.
* @return unsigned integer value that matches the 32 bits read.
*/
public static long decodeUInt32(final byte[] intbuf, final int offset) {
int low = (intbuf[offset + 1] & 0xff) << 8;
low |= (intbuf[offset + 2] & 0xff);
low <<= 8;
low |= (intbuf[offset + 3] & 0xff);
return ((long) (intbuf[offset] & 0xff)) << 24 | low;
}
/**
* Convert sequence of 8 bytes (network byte order) into unsigned value.
*
* @param intbuf
* buffer to acquire the 8 bytes of data from.
* @param offset
* position within the buffer to begin reading from. This
* position and the next 7 bytes after it (for a total of 8
* bytes) will be read.
* @return unsigned integer value that matches the 64 bits read.
*/
public static long decodeUInt64(final byte[] intbuf, final int offset) {
return (decodeUInt32(intbuf, offset) << 32)
| decodeUInt32(intbuf, offset + 4);
}
/**
* Write a 16 bit integer as a sequence of 2 bytes (network byte order).
*
* @param intbuf
* buffer to write the 2 bytes of data into.
* @param offset
* position within the buffer to begin writing to. This position
* and the next byte after it (for a total of 2 bytes) will be
* replaced.
* @param v
* the value to write.
*/
public static void encodeInt16(final byte[] intbuf, final int offset, int v) {
intbuf[offset + 1] = (byte) v;
v >>>= 8;
intbuf[offset] = (byte) v;
}
/**
* Write a 24 bit integer as a sequence of 3 bytes (network byte order).
*
* @param intbuf
* buffer to write the 3 bytes of data into.
* @param offset
* position within the buffer to begin writing to. This position
* and the next 2 bytes after it (for a total of 3 bytes) will be
* replaced.
* @param v
* the value to write.
* @since 4.9
*/
public static void encodeInt24(byte[] intbuf, int offset, int v) {
intbuf[offset + 2] = (byte) v;
v >>>= 8;
intbuf[offset + 1] = (byte) v;
v >>>= 8;
intbuf[offset] = (byte) v;
}
/**
* Write a 32 bit integer as a sequence of 4 bytes (network byte order).
*
* @param intbuf
* buffer to write the 4 bytes of data into.
* @param offset
* position within the buffer to begin writing to. This position
* and the next 3 bytes after it (for a total of 4 bytes) will be
* replaced.
* @param v
* the value to write.
*/
public static void encodeInt32(final byte[] intbuf, final int offset, int v) {
intbuf[offset + 3] = (byte) v;
v >>>= 8;
intbuf[offset + 2] = (byte) v;
v >>>= 8;
intbuf[offset + 1] = (byte) v;
v >>>= 8;
intbuf[offset] = (byte) v;
}
/**
* Write a 64 bit integer as a sequence of 8 bytes (network byte order).
*
* @param intbuf
* buffer to write the 8 bytes of data into.
* @param offset
* position within the buffer to begin writing to. This position
* and the next 7 bytes after it (for a total of 8 bytes) will be
* replaced.
* @param v
* the value to write.
*/
public static void encodeInt64(final byte[] intbuf, final int offset, long v) {
intbuf[offset + 7] = (byte) v;
v >>>= 8;
intbuf[offset + 6] = (byte) v;
v >>>= 8;
intbuf[offset + 5] = (byte) v;
v >>>= 8;
intbuf[offset + 4] = (byte) v;
v >>>= 8;
intbuf[offset + 3] = (byte) v;
v >>>= 8;
intbuf[offset + 2] = (byte) v;
v >>>= 8;
intbuf[offset + 1] = (byte) v;
v >>>= 8;
intbuf[offset] = (byte) v;
}
private NB() {
// Don't create instances of a static only utility.
}
}