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      1 /*
      2  * Copyright (C) 2017 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 android.location;
     18 
     19 import java.util.List;
     20 
     21 /*
     22  * Helper class to store single Satellite info, only used it in the unit test.
     23  */
     24 public class SatelliteInfo {
     25   private static final int SVID_MAX_BIT_INDEX = 32;
     26   private static final int SVID_SHIFT_WIDTH = 8;
     27   private static final int CONSTELLATION_TYPE_SHIFT_WIDTH = 4;
     28 
     29   // Index for the bits in mSvidWithFlag
     30   private static final int GNSS_SV_FLAGS_HAS_EPHEMERIS_DATA_BIT_INDEX = 0;
     31   private static final int GNSS_SV_FLAGS_HAS_ALMANAC_DATA_BIT_INDEX = 1;
     32   private static final int GNSS_SV_FLAGS_USED_IN_FIX_BIT_INDEX = 2;
     33   private static final int GNSS_SV_FLAGS_HAS_CARRIER_FREQUENCY_BIT_INDEX = 3;
     34   public int mSvid;
     35   public int mSvidWithFlag;
     36   public float mCn0DbHz;
     37   public float mElevation;
     38   public float mAzimuth;
     39   public float mCarrierFrequency;
     40 
     41   /*
     42    * Flag fields, it stores the same information as svidWithFlag, but in different format, easy for
     43    * the unit test.
     44    */
     45   public int mConstellationType;
     46   public boolean mHasEphemris;
     47   public boolean mHasAlmanac;
     48   public boolean mUsedInFix;
     49   public boolean mHasCarriesFrequency;
     50 
     51   public SatelliteInfo(int svid, int constellationType, boolean hasEphemris, boolean hasAlmanac,
     52       boolean usedInFix, boolean hasCarriesFrequency, float cn0, float elevation, float azimuth,
     53       float carrierFrequency) {
     54     mSvidWithFlag =
     55         setRange(mSvidWithFlag, constellationType, CONSTELLATION_TYPE_SHIFT_WIDTH, SVID_SHIFT_WIDTH);
     56     mSvidWithFlag = setRange(mSvidWithFlag, svid, SVID_SHIFT_WIDTH, SVID_MAX_BIT_INDEX);
     57     mSvidWithFlag = setBit(mSvidWithFlag, hasEphemris, GNSS_SV_FLAGS_HAS_EPHEMERIS_DATA_BIT_INDEX);
     58     mSvidWithFlag = setBit(mSvidWithFlag, hasAlmanac, GNSS_SV_FLAGS_HAS_ALMANAC_DATA_BIT_INDEX);
     59     mSvidWithFlag = setBit(mSvidWithFlag, usedInFix, GNSS_SV_FLAGS_USED_IN_FIX_BIT_INDEX);
     60     mSvidWithFlag =
     61         setBit(mSvidWithFlag, hasCarriesFrequency, GNSS_SV_FLAGS_HAS_CARRIER_FREQUENCY_BIT_INDEX);
     62     this.mSvid = svid;
     63     this.mConstellationType = constellationType;
     64     this.mCn0DbHz = cn0;
     65     this.mElevation = elevation;
     66     this.mAzimuth = azimuth;
     67     this.mCarrierFrequency = carrierFrequency;
     68     this.mHasEphemris = hasEphemris;
     69     this.mHasAlmanac = hasAlmanac;
     70     this.mUsedInFix = usedInFix;
     71     this.mHasCarriesFrequency = hasCarriesFrequency;
     72   }
     73 
     74   /*
     75    * Gernerate svidWithFlags array from svInfos
     76    */
     77   public static int[] getSvidWithFlagsArray(List<SatelliteInfo> svInfos) {
     78     int[] svidWithFlags = new int[svInfos.size()];
     79     for (int i = 0; i< svInfos.size(); i++) {
     80       svidWithFlags[i] = svInfos.get(i).mSvidWithFlag;
     81     }
     82     return svidWithFlags;
     83   }
     84 
     85   /*
     86    * Gernerate cn0s array from svInfos
     87    */
     88   public static float[] getCn0sArray(List<SatelliteInfo> svInfos) {
     89     float[] cn0s = new float[svInfos.size()];
     90     for (int i = 0; i< svInfos.size(); i++) {
     91       cn0s[i] = svInfos.get(i).mCn0DbHz;
     92     }
     93     return cn0s;
     94   }
     95 
     96   /*
     97    * Gernerate elevations array from svInfos
     98    */
     99   public static float[] getElevationsArray(List<SatelliteInfo> svInfos) {
    100     float[] elevations = new float[svInfos.size()];
    101     for (int i = 0; i< svInfos.size(); i++) {
    102       elevations[i] = svInfos.get(i).mElevation;
    103     }
    104     return elevations;
    105   }
    106 
    107   /*
    108    * Gernerate azimuths array from svInfos
    109    */
    110   public static float[] getAzimuthsArray(List<SatelliteInfo> svInfos) {
    111     float[] azimuths = new float[svInfos.size()];
    112     for (int i = 0; i< svInfos.size(); i++) {
    113       azimuths[i] = svInfos.get(i).mAzimuth;
    114     }
    115     return azimuths;
    116   }
    117 
    118   /*
    119    * Gernerate carrierFrequency array from svInfos
    120    */
    121   public static float[] getCarrierFrequencyArray(List<SatelliteInfo> svInfos) {
    122     float[] carrierFrequencies = new float[svInfos.size()];
    123     for (int i = 0; i< svInfos.size(); i++) {
    124       carrierFrequencies[i] = svInfos.get(i).mCarrierFrequency;
    125     }
    126     return carrierFrequencies;
    127   }
    128 
    129   private int setBit(int targetValue, boolean value, int index) {
    130     if (value) {
    131       targetValue = targetValue | (1 << index);
    132     } else {
    133       targetValue = targetValue & ~(1 << index);
    134     }
    135     return targetValue;
    136   }
    137 
    138   /*
    139    * Set the bit in the range [fromIndex, toIndex), index start from the lowest bit.
    140    * value -> 1 1 0 1 1 0 1 0
    141    * index -> 7 6 5 4 3 2 1 0
    142    * This function will set the bit in the range to the lowest X bits of the value.
    143    */
    144   private int setRange(int targetValue, int value, int fromIndex, int toIndex) {
    145     int rangeLen = toIndex - fromIndex;
    146     int valueMask = (1 << rangeLen) -1;
    147     value &= valueMask;
    148     value = value << fromIndex;
    149     valueMask = valueMask << fromIndex;
    150     targetValue &= (~valueMask);
    151     targetValue |= value;
    152     return targetValue;
    153   }
    154 
    155 }