Add method to read more than 32 bits in ParsableBitArray

PiperOrigin-RevId: 277766372

library/core/src/main/java/com/google/android/exoplayer2/util/ParsableBitArray.java

@@ -163,7 +163,7 @@ public final class ParsableBitArray {
    * Reads up to 32 bits.
    *
    * @param numBits The number of bits to read.
-   * @return An integer whose bottom n bits hold the read data.
+   * @return An integer whose bottom {@code numBits} bits hold the read data.
    */
   public int readBits(int numBits) {
     if (numBits == 0) {
@@ -185,12 +185,25 @@ public final class ParsableBitArray {
     return returnValue;
   }
 
+  /**
+   * Reads up to 64 bits.
+   *
+   * @param numBits The number of bits to read.
+   * @return A long whose bottom {@code numBits} bits hold the read data.
+   */
+  public long readBitsToLong(int numBits) {
+    if (numBits <= 32) {
+      return Util.toUnsignedLong(readBits(numBits));
+    }
+    return Util.toUnsignedLong(readBits(numBits - 32)) << 32 | Util.toUnsignedLong(readBits(32));
+  }
+
   /**
    * Reads {@code numBits} bits into {@code buffer}.
    *
-   * @param buffer The array into which the read data should be written. The trailing
-   *     {@code numBits % 8} bits are written into the most significant bits of the last modified
-   *     {@code buffer} byte. The remaining ones are unmodified.
+   * @param buffer The array into which the read data should be written. The trailing {@code numBits
+   *     % 8} bits are written into the most significant bits of the last modified {@code buffer}
+   *     byte. The remaining ones are unmodified.
    * @param offset The offset in {@code buffer} at which the read data should be written.
    * @param numBits The number of bits to read.
    */

library/core/src/main/java/com/google/android/exoplayer2/util/Util.java

@@ -146,7 +146,7 @@ public final class Util {
    * Converts the entirety of an {@link InputStream} to a byte array.
    *
    * @param inputStream the {@link InputStream} to be read. The input stream is not closed by this
-   *    method.
+   *     method.
    * @return a byte array containing all of the inputStream's bytes.
    * @throws IOException if an error occurs reading from the stream.
    */
@@ -366,7 +366,6 @@ public final class Util {
         /* length= */ second.length);
     return concatenation;
   }
-
   /**
    * Creates a {@link Handler} with the specified {@link Handler.Callback} on the current {@link
    * Looper} thread. The method accepts partially initialized objects as callback under the
@@ -1192,6 +1191,17 @@ public final class Util {
     return result;
   }
 
+  /**
+   * Converts an integer to a long by unsigned conversion.
+   *
+   * <p>This method is equivalent to {@link Integer#toUnsignedLong(int)} for API 26+.
+   */
+  public static long toUnsignedLong(int x) {
+    // x is implicitly casted to a long before the bit operation is executed but this does not
+    // impact the method correctness.
+    return x & 0xFFFFFFFFL;
+  }
+
   /**
    * Returns a byte array containing values parsed from the hex string provided.
    *

library/core/src/test/java/com/google/android/exoplayer2/util/ParsableBitArrayTest.java

@@ -107,6 +107,50 @@ public final class ParsableBitArrayTest {
     assertThat(result).isEqualTo(0xF0000000);
   }
 
+  @Test
+  public void testReadBitsToLong0Bits() {
+    byte[] testData = TestUtil.createByteArray(0x3C);
+    ParsableBitArray testArray = new ParsableBitArray(testData);
+
+    long result = testArray.readBitsToLong(0);
+
+    assertThat(result).isEqualTo(0);
+  }
+
+  @Test
+  public void testReadBitsToLongByteAligned() {
+    byte[] testData = TestUtil.createByteArray(0x3C, 0xD2, 0x5F, 0x01, 0xFF, 0x14, 0x60);
+    ParsableBitArray testArray = new ParsableBitArray(testData);
+    testArray.readBits(8);
+
+    long result = testArray.readBitsToLong(45);
+
+    assertThat(result).isEqualTo(0xD25F01FF14L << 5 | 0x60 >> 3);
+    assertThat(testArray.getPosition()).isEqualTo(53);
+  }
+
+  @Test
+  public void testReadBitsToLongNonByteAligned() {
+    byte[] testData = TestUtil.createByteArray(0x3C, 0xD2, 0x5F, 0x01, 0xFF, 0x14, 0x60);
+    ParsableBitArray testArray = new ParsableBitArray(testData);
+    testArray.readBits(3);
+
+    long result = testArray.readBitsToLong(53);
+
+    assertThat(result).isEqualTo((0x3CL & 0b11111) << 48 | 0xD25F01FF1460L);
+    assertThat(testArray.getPosition()).isEqualTo(56);
+  }
+
+  @Test
+  public void testReadBitsToLongNegativeValue() {
+    byte[] testData = TestUtil.createByteArray(0xF0, 0, 0, 0, 0, 0, 0, 0);
+    ParsableBitArray testArray = new ParsableBitArray(testData);
+
+    long result = testArray.readBitsToLong(64);
+
+    assertThat(result).isEqualTo(0xF000000000000000L);
+  }
+
   @Test
   public void testReadBitsToByteArray() {
     byte[] testData = TestUtil.createByteArray(0x3C, 0xD2, 0x5F, 0x01, 0xFF, 0x14, 0x60, 0x99);

library/core/src/test/java/com/google/android/exoplayer2/util/UtilTest.java

@@ -217,6 +217,24 @@ public class UtilTest {
     assertThat(parseXsDateTime("2014-09-19T13:18:55.000-800")).isEqualTo(1411161535000L);
   }
 
+  @Test
+  public void testToUnsignedLongPositiveValue() {
+    int x = 0x05D67F23;
+
+    long result = Util.toUnsignedLong(x);
+
+    assertThat(result).isEqualTo(0x05D67F23L);
+  }
+
+  @Test
+  public void testToUnsignedLongNegativeValue() {
+    int x = 0xF5D67F23;
+
+    long result = Util.toUnsignedLong(x);
+
+    assertThat(result).isEqualTo(0xF5D67F23L);
+  }
+
   @Test
   public void testGetCodecsOfType() {
     assertThat(getCodecsOfType(null, C.TRACK_TYPE_VIDEO)).isNull();