Move wifi/ScanResult.averageRssi logic to service

Move the averaging logic formerly in
  android.net.wifi.ScanResult#averageRssi()
to inline code in the one place it was used.

This needs a unit test, but defer adding one for a later CL because
the value of doing this averaging at all should be revaluated.

No functional change.

Bug: 68401944
Test: Unit tests
Test: Manually check logging
Change-Id: I7d4f5860726c1870b1fe21aeaa2f432961218397

1 files changed, 8 insertions, 1 deletions

diff --git a/service/java/com/android/server/wifi/WifiConfigManager.java b/service/java/com/android/server/wifi/WifiConfigManager.java
index e443cd425..ffde57f7e 100644
--- a/service/java/com/android/server/wifi/WifiConfigManager.java
+++ b/service/java/com/android/server/wifi/WifiConfigManager.java
@@ -1996,7 +1996,14 @@ public class WifiConfigManager {
                 scanDetail.setSeen();
                 result.level = info.getRssi();
                 // Average the RSSI value
-                result.averageRssi(previousRssi, previousSeen, SCAN_RESULT_MAXIMUM_AGE_MS);
+                long maxAge = SCAN_RESULT_MAXIMUM_AGE_MS;
+                long age = result.seen - previousSeen;
+                if (previousSeen > 0 && age > 0 && age < maxAge / 2) {
+                    // Average the RSSI with previously seen instances of this scan result
+                    double alpha = 0.5 - (double) age / (double) maxAge;
+                    result.level = (int) ((double) result.level * (1 - alpha)
+                                        + (double) previousRssi * alpha);
+                }
                 if (mVerboseLoggingEnabled) {
                     Log.v(TAG, "Updating scan detail cache freq=" + result.frequency
                             + " BSSID=" + result.BSSID