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- /*
- * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
- * and other copyright owners as documented in the project's IP log.
- *
- * This program and the accompanying materials are made available
- * under the terms of the Eclipse Distribution License v1.0 which
- * accompanies this distribution, is reproduced below, and is
- * available at http://www.eclipse.org/org/documents/edl-v10.php
- *
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or
- * without modification, are permitted provided that the following
- * conditions are met:
- *
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * - Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following
- * disclaimer in the documentation and/or other materials provided
- * with the distribution.
- *
- * - Neither the name of the Eclipse Foundation, Inc. nor the
- * names of its contributors may be used to endorse or promote
- * products derived from this software without specific prior
- * written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
- * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
- * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
- 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);
- }
-
- /**
- * 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 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 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.
- }
- }
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