Fix WCDMA Level Calculation for Default CC

The default carrier config was setting the level
calculation method to an empty string, which caused
the level to be set forcibly to NONE/UNKNOWN due to
the logic failing to account for empty strings. This
patch sets the default to something sane "rssi" that
matches legacy behavior and also adds guards so that
an empty string will be considered default, and a non
empty but otherwise invalid string will also try to
use RSSI instead of simply failing to display signal
bars.

-Add protection against invalid array sizes
-Fix a bug where RSCP could use RSSI thresholds
-Add fallback for RSCP thresholds being null when the
 measurement type is set to RSCP.
-Define RSCP thresholds as constants.

Bug: 118800169
Test: atest CellSignalStrengthWcdmaTest
Change-Id: I8d6261bc5adab6bf9b0a88f7d59b259d338a49e9

3 files changed, 63 insertions, 18 deletions

diff --git a/telephony/java/android/telephony/CarrierConfigManager.java b/telephony/java/android/telephony/CarrierConfigManager.java
index 4561ea33bb95..89b646fa0728 100644
--- a/telephony/java/android/telephony/CarrierConfigManager.java
+++ b/telephony/java/android/telephony/CarrierConfigManager.java
@@ -2242,7 +2242,7 @@ public class CarrierConfigManager {
      * e.g.) To use RSCP by default, set the value to "rscp". The signal strength level will
      * then be determined by #KEY_WCDMA_RSCP_THRESHOLDS_INT_ARRAY
      * <p>
-     * Currently this only supports the value "rscp"
+     * Currently this supports the value "rscp" and "rssi".
      * @hide
      */
     // FIXME: this key and related keys must not be exposed without a consistent philosophy for
@@ -2690,7 +2690,7 @@ public class CarrierConfigManager {
                         -95, /* SIGNAL_STRENGTH_GOOD */
                         -85  /* SIGNAL_STRENGTH_GREAT */
                 });
-        sDefaults.putString(KEY_WCDMA_DEFAULT_SIGNAL_STRENGTH_MEASUREMENT_STRING, "");
+        sDefaults.putString(KEY_WCDMA_DEFAULT_SIGNAL_STRENGTH_MEASUREMENT_STRING, "rssi");
         sDefaults.putBoolean(KEY_CONFIG_SHOW_ORIG_DIAL_STRING_FOR_CDMA_BOOL, false);
         sDefaults.putBoolean(KEY_SHOW_CALL_BLOCKING_DISABLED_NOTIFICATION_ALWAYS_BOOL, false);
         sDefaults.putBoolean(KEY_CALL_FORWARDING_OVER_UT_WARNING_BOOL, false);
diff --git a/telephony/java/android/telephony/CellSignalStrength.java b/telephony/java/android/telephony/CellSignalStrength.java
index a18275f95f9d..7d07a730f78b 100644
--- a/telephony/java/android/telephony/CellSignalStrength.java
+++ b/telephony/java/android/telephony/CellSignalStrength.java
@@ -42,6 +42,9 @@ public abstract class CellSignalStrength {
     public static final int NUM_SIGNAL_STRENGTH_BINS = 5;
 
     /** @hide */
+    protected static final int NUM_SIGNAL_STRENGTH_THRESHOLDS = NUM_SIGNAL_STRENGTH_BINS - 1;
+
+    /** @hide */
     public static final String[] SIGNAL_STRENGTH_NAMES = {
         "none", "poor", "moderate", "good", "great"
     };
diff --git a/telephony/java/android/telephony/CellSignalStrengthWcdma.java b/telephony/java/android/telephony/CellSignalStrengthWcdma.java
index 88f6fbc4464d..0760407171ae 100644
--- a/telephony/java/android/telephony/CellSignalStrengthWcdma.java
+++ b/telephony/java/android/telephony/CellSignalStrengthWcdma.java
@@ -21,6 +21,7 @@ import android.os.Parcel;
 import android.os.Parcelable;
 import android.os.PersistableBundle;
 import android.telephony.Rlog;
+import android.text.TextUtils;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -41,8 +42,18 @@ public final class CellSignalStrengthWcdma extends CellSignalStrength implements
     private static final int WCDMA_RSSI_POOR = -107;
     private static final int WCDMA_RSSI_MIN = -113;
 
-    private static final int WCDMA_RSCP_MIN = -120;
+    private static final int[] sRssiThresholds = new int[]{
+            WCDMA_RSSI_POOR, WCDMA_RSSI_MODERATE, WCDMA_RSSI_GOOD, WCDMA_RSSI_GREAT};
+
     private static final int WCDMA_RSCP_MAX = -24;
+    private static final int WCDMA_RSCP_GREAT = -85;
+    private static final int WCDMA_RSCP_GOOD = -95;
+    private static final int WCDMA_RSCP_MODERATE = -105;
+    private static final int WCDMA_RSCP_POOR = -115;
+    private static final int WCDMA_RSCP_MIN = -120;
+
+    private static final int[] sRscpThresholds = new int[] {
+            WCDMA_RSCP_POOR, WCDMA_RSCP_MODERATE, WCDMA_RSCP_GOOD, WCDMA_RSCP_GREAT};
 
     // TODO: Because these are used as values in CarrierConfig, they should be exposed somehow.
     /** @hide */
@@ -54,6 +65,9 @@ public final class CellSignalStrengthWcdma extends CellSignalStrength implements
     /** @hide */
     public static final String LEVEL_CALCULATION_METHOD_RSCP = "rscp";
 
+    // Default to RSSI for backwards compatibility with older devices
+    private static final String sLevelCalculationMethod = LEVEL_CALCULATION_METHOD_RSSI;
+
     private int mRssi; // in dBm [-113, 51] or CellInfo.UNAVAILABLE if unknown
     private int mBitErrorRate; // bit error rate (0-7, 99) as defined in TS 27.007 8.5 or
                                // CellInfo.UNAVAILABLE if unknown
@@ -121,10 +135,6 @@ public final class CellSignalStrengthWcdma extends CellSignalStrength implements
         mLevel = SIGNAL_STRENGTH_NONE_OR_UNKNOWN;
     }
 
-    private static final String sLevelCalculationMethod = LEVEL_CALCULATION_METHOD_RSSI;
-    private static final int[] sThresholds = new int[]{
-            WCDMA_RSSI_POOR, WCDMA_RSSI_GOOD, WCDMA_RSSI_GOOD, WCDMA_RSSI_GREAT};
-
     /**
      * Retrieve an abstract level value for the overall signal strength.
      *
@@ -140,41 +150,46 @@ public final class CellSignalStrengthWcdma extends CellSignalStrength implements
     @Override
     public void updateLevel(PersistableBundle cc, ServiceState ss) {
         String calcMethod;
-        int[] thresholds;
+        int[] rscpThresholds;
 
         if (cc == null) {
             calcMethod = sLevelCalculationMethod;
-            thresholds = sThresholds;
+            rscpThresholds = sRscpThresholds;
         } else {
             // TODO: abstract this entire thing into a series of functions
             calcMethod = cc.getString(
                     CarrierConfigManager.KEY_WCDMA_DEFAULT_SIGNAL_STRENGTH_MEASUREMENT_STRING,
                     sLevelCalculationMethod);
-            thresholds = cc.getIntArray(
+            if (TextUtils.isEmpty(calcMethod)) calcMethod = sLevelCalculationMethod;
+            rscpThresholds = cc.getIntArray(
                     CarrierConfigManager.KEY_WCDMA_RSCP_THRESHOLDS_INT_ARRAY);
-            if (thresholds == null) thresholds = sThresholds;
+            if (rscpThresholds == null || rscpThresholds.length != NUM_SIGNAL_STRENGTH_THRESHOLDS) {
+                rscpThresholds = sRscpThresholds;
+            }
         }
 
-        int level = thresholds.length;
+        int level = NUM_SIGNAL_STRENGTH_THRESHOLDS;
         switch (calcMethod) {
             case LEVEL_CALCULATION_METHOD_RSCP:
                 if (mRscp < WCDMA_RSCP_MIN || mRscp > WCDMA_RSCP_MAX) {
                     mLevel = SIGNAL_STRENGTH_NONE_OR_UNKNOWN;
                     return;
                 }
-                while (level > 0 && mRscp < thresholds[level - 1]) level--;
+                while (level > 0 && mRscp < rscpThresholds[level - 1]) level--;
                 mLevel = level;
                 return;
+            default:
+                loge("Invalid Level Calculation Method for CellSignalStrengthWcdma = "
+                        + calcMethod);
+                /** fall through */
             case LEVEL_CALCULATION_METHOD_RSSI:
                 if (mRssi < WCDMA_RSSI_MIN || mRssi > WCDMA_RSSI_MAX) {
                     mLevel = SIGNAL_STRENGTH_NONE_OR_UNKNOWN;
                     return;
                 }
-                while (level > 0 && mRssi < thresholds[level - 1]) level--;
+                while (level > 0 && mRssi < sRssiThresholds[level - 1]) level--;
                 mLevel = level;
                 return;
-            default:
-                mLevel = SIGNAL_STRENGTH_NONE_OR_UNKNOWN;
         }
     }
 
@@ -204,7 +219,7 @@ public final class CellSignalStrengthWcdma extends CellSignalStrength implements
     }
 
     /**
-     * Get the signal strength as dBm
+     * Get the RSSI as dBm
      *
      * @hide
      */
@@ -214,12 +229,32 @@ public final class CellSignalStrengthWcdma extends CellSignalStrength implements
 
     /**
      * Get the RSCP as dBm
+     *
      * @hide
      */
     public int getRscp() {
         return mRscp;
     }
 
+    /**
+     * Get the Ec/No as dB
+     *
+     * @hide
+     */
+    public int getEcNo() {
+        return mEcNo;
+    }
+
+    /**
+     * Return the Bit Error Rate
+     *
+     * @returns the bit error rate (0-7, 99) as defined in TS 27.007 8.5 or UNAVAILABLE.
+     * @hide
+     */
+    public int getBitErrorRate() {
+        return mBitErrorRate;
+    }
+
     @Override
     public int hashCode() {
         return Objects.hash(mRssi, mBitErrorRate, mRscp, mEcNo, mLevel);
@@ -304,9 +339,16 @@ public final class CellSignalStrengthWcdma extends CellSignalStrength implements
     };
 
     /**
-     * log
+     * log warning
      */
     private static void log(String s) {
         Rlog.w(LOG_TAG, s);
     }
+
+    /**
+     * log error
+     */
+    private static void loge(String s) {
+        Rlog.e(LOG_TAG, s);
+    }
 }