1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.dexgen.util; 18 19 /** 20 * LEB128 (little-endian base 128) utilities. 21 */ 22 public final class Leb128Utils { 23 /** 24 * This class is uninstantiable. 25 */ Leb128Utils()26 private Leb128Utils() { 27 // This space intentionally left blank. 28 } 29 30 /** 31 * Gets the number of bytes in the unsigned LEB128 encoding of the 32 * given value. 33 * 34 * @param value the value in question 35 * @return its write size, in bytes 36 */ unsignedLeb128Size(int value)37 public static int unsignedLeb128Size(int value) { 38 // TODO: This could be much cleverer. 39 40 int remaining = value >> 7; 41 int count = 0; 42 43 while (remaining != 0) { 44 remaining >>= 7; 45 count++; 46 } 47 48 return count + 1; 49 } 50 51 /** 52 * Gets the number of bytes in the signed LEB128 encoding of the 53 * given value. 54 * 55 * @param value the value in question 56 * @return its write size, in bytes 57 */ signedLeb128Size(int value)58 public static int signedLeb128Size(int value) { 59 // TODO: This could be much cleverer. 60 61 int remaining = value >> 7; 62 int count = 0; 63 boolean hasMore = true; 64 int end = ((value & Integer.MIN_VALUE) == 0) ? 0 : -1; 65 66 while (hasMore) { 67 hasMore = (remaining != end) 68 || ((remaining & 1) != ((value >> 6) & 1)); 69 70 value = remaining; 71 remaining >>= 7; 72 count++; 73 } 74 75 return count; 76 } 77 } 78