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/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed 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.
*/
/*
* As per the Apache license requirements, this file has been modified
* from its original state.
*
* Such modifications are Copyright (C) 2010 Ben Gruver, and are released
* under the original license
*/
package org.jf.dexlib.Util;
/**
* LEB128 (little-endian base 128) utilities.
*/
public final class Leb128Utils {
/**
* This class is uninstantiable.
*/
private Leb128Utils() {
// This space intentionally left blank.
}
/**
* Gets the number of bytes in the unsigned LEB128 encoding of the
* given value.
*
* @param value the value in question
* @return its write size, in bytes
*/
public static int unsignedLeb128Size(int value) {
// TODO: This could be much cleverer.
int remaining = value >>> 7;
int count = 0;
while (remaining != 0) {
value = remaining;
remaining >>>= 7;
count++;
}
return count + 1;
}
/**
* Gets the number of bytes in the signed LEB128 encoding of the
* given value.
*
* @param value the value in question
* @return its write size, in bytes
*/
public static int signedLeb128Size(int value) {
// TODO: This could be much cleverer.
int remaining = value >> 7;
int count = 0;
boolean hasMore = true;
int end = ((value & Integer.MIN_VALUE) == 0) ? 0 : -1;
while (hasMore) {
hasMore = (remaining != end)
|| ((remaining & 1) != ((value >> 6) & 1));
value = remaining;
remaining >>= 7;
count++;
}
return count;
}
/**
* Writes an unsigned leb128 to the buffer at the specified location
* @param value the value to write as an unsigned leb128
* @param buffer the buffer to write to
* @param bufferIndex the index to start writing at
*/
public static void writeUnsignedLeb128(int value, byte[] buffer, int bufferIndex) {
int remaining = value >>> 7;
int count = 0;
while (remaining != 0) {
buffer[bufferIndex] = (byte)((value & 0x7f) | 0x80);
bufferIndex++;
value = remaining;
remaining >>>= 7;
count++;
}
buffer[bufferIndex] = (byte)(value & 0x7f);
}
}
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