Fix Util.scaleLargeValue/Timestamp to handle negative numbers

#minor-release

PiperOrigin-RevId: 570337535

libraries/common/src/main/java/androidx/media3/common/util/Util.java

@@ -1840,12 +1840,13 @@ public final class Util {
       // Directly multiplying value and multiplier will overflow a long, so we try and cancel
       // with GCD and try directly multiplying again below. If that still overflows we fall
       // through to floating point arithmetic.
-      long gcdOfMultiplierAndDivisor = LongMath.gcd(multiplier, divisor);
+      long gcdOfMultiplierAndDivisor = LongMath.gcd(Math.abs(multiplier), Math.abs(divisor));
       long simplifiedMultiplier =
           LongMath.divide(multiplier, gcdOfMultiplierAndDivisor, RoundingMode.UNNECESSARY);
       long simplifiedDivisor =
           LongMath.divide(divisor, gcdOfMultiplierAndDivisor, RoundingMode.UNNECESSARY);
-      long gcdOfValueAndSimplifiedDivisor = LongMath.gcd(value, simplifiedDivisor);
+      long gcdOfValueAndSimplifiedDivisor =
+          LongMath.gcd(Math.abs(value), Math.abs(simplifiedDivisor));
       long simplifiedValue =
           LongMath.divide(value, gcdOfValueAndSimplifiedDivisor, RoundingMode.UNNECESSARY);
       simplifiedDivisor =

libraries/common/src/test/java/androidx/media3/common/util/UtilScaleLargeValueParameterizedTest.java

@@ -18,11 +18,14 @@ package androidx.media3.common.util;
 import static androidx.media3.common.util.Assertions.checkState;
 import static com.google.common.truth.Truth.assertThat;
 import static org.junit.Assert.assertThrows;
+import static org.junit.Assume.assumeFalse;
 import static org.junit.Assume.assumeTrue;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.math.LongMath;
 import java.math.RoundingMode;
+import java.util.ArrayList;
+import java.util.List;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.robolectric.ParameterizedRobolectricTestRunner;
@@ -45,54 +48,92 @@ public class UtilScaleLargeValueParameterizedTest {
 
   @Parameters(name = "{0}")
   public static ImmutableList<Object[]> implementations() {
-    return ImmutableList.of(
+    ImmutableList<Implementation> implementations =
-        new Object[] {"single-value", (ScaleLargeValueFn) Util::scaleLargeValue},
+        ImmutableList.of(
-        new Object[] {
+            new Implementation("single-value", Util::scaleLargeValue),
+            new Implementation(
                 "list",
-          (ScaleLargeValueFn)
                 (value, multiplier, divisor, roundingMode) ->
-                  Util.scaleLargeValues(ImmutableList.of(value), multiplier, divisor, roundingMode)[
+                    Util.scaleLargeValues(
-                      0]
+                        ImmutableList.of(value), multiplier, divisor, roundingMode)[0]),
-        },
+            new Implementation(
-        new Object[] {
                 "array-in-place",
-          (ScaleLargeValueFn)
                 (value, multiplier, divisor, roundingMode) -> {
                   long[] values = new long[] {value};
                   Util.scaleLargeValuesInPlace(values, multiplier, divisor, roundingMode);
                   return values[0];
-              }
+                }),
-        },
+            new Implementation(
-        new Object[] {
                 "single-timestamp",
-          (ScaleLargeValueFn)
                 (long timestamp, long multiplier, long divisor, RoundingMode roundingMode) -> {
                   assumeTrue(
-                    roundingMode == RoundingMode.UNNECESSARY || roundingMode == RoundingMode.FLOOR);
+                      roundingMode == RoundingMode.UNNECESSARY
+                          || roundingMode == RoundingMode.FLOOR);
                   return Util.scaleLargeTimestamp(timestamp, multiplier, divisor);
-              }
+                }),
-        },
+            new Implementation(
-        new Object[] {
                 "timestamp-list",
-          (ScaleLargeValueFn)
                 (timestamp, multiplier, divisor, roundingMode) -> {
                   assumeTrue(
-                    roundingMode == RoundingMode.UNNECESSARY || roundingMode == RoundingMode.FLOOR);
+                      roundingMode == RoundingMode.UNNECESSARY
-                return Util.scaleLargeTimestamps(ImmutableList.of(timestamp), multiplier, divisor)[
+                          || roundingMode == RoundingMode.FLOOR);
-                    0];
+                  return Util.scaleLargeTimestamps(
-              }
+                      ImmutableList.of(timestamp), multiplier, divisor)[0];
-        },
+                }),
-        new Object[] {
+            new Implementation(
                 "timestamp-array-in-place",
-          (ScaleLargeValueFn)
                 (timestamp, multiplier, divisor, roundingMode) -> {
                   assumeTrue(
-                    roundingMode == RoundingMode.UNNECESSARY || roundingMode == RoundingMode.FLOOR);
+                      roundingMode == RoundingMode.UNNECESSARY
+                          || roundingMode == RoundingMode.FLOOR);
                   long[] timestamps = new long[] {timestamp};
                   Util.scaleLargeTimestampsInPlace(timestamps, multiplier, divisor);
                   return timestamps[0];
+                }));
+
+    List<Implementation> implementationsWithNegativeCases = new ArrayList<>();
+    for (Implementation implementation : implementations) {
+      implementationsWithNegativeCases.add(implementation);
+      implementationsWithNegativeCases.add(
+          new Implementation(
+              implementation.name + "-negative-value",
+              (value, multiplier, divisor, roundingMode) -> {
+                assumeTrue(roundingMode == RoundingMode.UNNECESSARY);
+                long result =
+                    implementation.scaleFn.scaleLargeValue(
+                        -value, multiplier, divisor, roundingMode);
+                assumeFalse(result == Long.MIN_VALUE || result == Long.MAX_VALUE);
+                return -result;
+              }));
+      implementationsWithNegativeCases.add(
+          new Implementation(
+              implementation.name + "-negative-multiplier",
+              (value, multiplier, divisor, roundingMode) -> {
+                assumeTrue(roundingMode == RoundingMode.UNNECESSARY);
+                long result =
+                    implementation.scaleFn.scaleLargeValue(
+                        value, -multiplier, divisor, roundingMode);
+                assumeFalse(result == Long.MIN_VALUE || result == Long.MAX_VALUE);
+                return -result;
+              }));
+      implementationsWithNegativeCases.add(
+          new Implementation(
+              implementation.name + "-negative-divisor",
+              (value, multiplier, divisor, roundingMode) -> {
+                assumeTrue(roundingMode == RoundingMode.UNNECESSARY);
+                long result =
+                    implementation.scaleFn.scaleLargeValue(
+                        value, multiplier, -divisor, roundingMode);
+                assumeFalse(result == Long.MIN_VALUE || result == Long.MAX_VALUE);
+                return -result;
+              }));
     }
-        });
+
+    ImmutableList.Builder<Object[]> implementationsAsObjectArray = ImmutableList.builder();
+    for (Implementation implementation : implementationsWithNegativeCases) {
+      implementationsAsObjectArray.add(new Object[] {implementation.name, implementation.scaleFn});
+    }
+    return implementationsAsObjectArray.build();
   }
 
   // Every parameter has to be assigned to a field, even if it's only used to name the test.
@@ -277,6 +318,16 @@ public class UtilScaleLargeValueParameterizedTest {
     assertThat(result).isEqualTo(Long.MAX_VALUE);
   }
 
+  private static final class Implementation {
+    public final String name;
+    public final ScaleLargeValueFn scaleFn;
+
+    private Implementation(String name, ScaleLargeValueFn scaleFn) {
+      this.name = name;
+      this.scaleFn = scaleFn;
+    }
+  }
+
   private interface ScaleLargeValueFn {
     long scaleLargeValue(long value, long multiplier, long divisor, RoundingMode roundingMode);
   }