1 /* 2 * Copyright (C) 2016 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 package android.car; 17 18 import android.annotation.SystemApi; 19 20 /** 21 * Collection of utilities for handling zones 22 * @hide 23 */ 24 @SystemApi 25 public final class VehicleZoneUtil { 26 27 /** 28 * Change zone flag into index with available zones. 29 * For example with zoned of 0x80000001, 0x1 will be index 0 and 0x80000000 will be index 2. 30 * @param available zones, should not be zero 31 * @param zone flag for the zone to get index, should not be zero and should be one of the flags 32 * defined in zones. 33 * @return index of desired zone. 34 * @throws IllegalArgumentException if zones or zone is invalid. 35 */ 36 public static int zoneToIndex(int zones, int zone) throws IllegalArgumentException { 37 if ((zone == 0) || // check that zone is non-zero 38 ((zone & zones) != zone) || // check that zone is inside of zones 39 ((zone & (zone - 1)) != 0)) { // check that zone only has one bit set 40 throw new IllegalArgumentException("Invalid zones 0x" + Integer.toHexString(zones) + 41 " or zone 0x" + Integer.toHexString(zone)); 42 } 43 int index = -1; 44 while((zone & zones) != 0) { 45 index++; 46 zones &= zones - 1; 47 } 48 return index; 49 } 50 51 /** 52 * Return number of zones (non-zero flag) from given zones. 53 */ 54 public static int getNumberOfZones(int zones) { 55 int numZones = 0; 56 while (zones != 0) { 57 zones &= zones - 1; 58 numZones++; 59 } 60 return numZones; 61 } 62 63 /** 64 * Return bit flag of first zone. If zones is 0, it will just return 0. 65 * @param zones can be 0 if there is no zone 66 * @return 67 */ 68 public static int getFirstZone(int zones) { 69 if (zones == 0) { 70 return 0; 71 } 72 int xorFlag = zones & (zones - 1); 73 74 return zones ^ xorFlag; 75 } 76 77 /** 78 * Return bit flag of zone available after startingZone. For zones of 0x7 with startingZone of 79 * 0x2, it will return 0x4. If no zone exist after startingZone, it will return 0. 80 * @param zones 81 * @param startingZone A bit flag representing a zone. This does not necessarily be one of flags 82 * available in zones. 83 * @return 84 * @throws IllegalArgumentException If startingZone is invalid. 85 */ 86 public static int getNextZone(int zones, int startingZone) throws IllegalArgumentException { 87 if ((startingZone & (startingZone - 1)) != 0 || startingZone == 0) { 88 throw new IllegalArgumentException( 89 "Starting zone should represent only one bit flag: 0x" + 90 Integer.toHexString(startingZone)); 91 } 92 93 // Create a mask that sets all bits above the current one 94 int mask = startingZone << 1; 95 mask -= 1; 96 mask = ~mask; 97 return getFirstZone(zones & mask); 98 } 99 100 /** 101 * Return array of zone with each active zone in one index. This can be useful for iterating 102 * all available zones. 103 */ 104 public static int[] listAllZones(int zones) { 105 int numberOfZones = getNumberOfZones(zones); 106 int[] list = new int[numberOfZones]; 107 if (numberOfZones == 0) { 108 return list; 109 } 110 111 int arrayIndex = 0; 112 while (zones != 0) { 113 int xorFlag = zones & (zones - 1); 114 int zone = zones ^ xorFlag; 115 list[arrayIndex++] = zone; 116 zones = xorFlag; 117 } 118 return list; 119 } 120 121 private VehicleZoneUtil() {} 122 } 123
