From 8378c3dc1f0247d85d57ab81d75596a3a79345fb Mon Sep 17 00:00:00 2001 From: olly Date: Thu, 13 Jul 2017 05:59:15 -0700 Subject: [PATCH] Simplify + optimize VorbisBitArray ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=161796758 --- .../extractor/ogg/VorbisBitArrayTest.java | 131 ------------------ .../extractor/ogg/VorbisBitArray.java | 85 ++++-------- 2 files changed, 28 insertions(+), 188 deletions(-) diff --git a/library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/ogg/VorbisBitArrayTest.java b/library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/ogg/VorbisBitArrayTest.java index 9a65cad6a5..a24cb1599b 100644 --- a/library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/ogg/VorbisBitArrayTest.java +++ b/library/core/src/androidTest/java/com/google/android/exoplayer2/extractor/ogg/VorbisBitArrayTest.java @@ -25,36 +25,26 @@ public final class VorbisBitArrayTest extends TestCase { public void testReadBit() { VorbisBitArray bitArray = new VorbisBitArray(TestUtil.createByteArray(0x5c, 0x50)); - assertFalse(bitArray.readBit()); assertFalse(bitArray.readBit()); assertTrue(bitArray.readBit()); assertTrue(bitArray.readBit()); - assertTrue(bitArray.readBit()); assertFalse(bitArray.readBit()); assertTrue(bitArray.readBit()); assertFalse(bitArray.readBit()); - assertFalse(bitArray.readBit()); assertFalse(bitArray.readBit()); assertFalse(bitArray.readBit()); assertFalse(bitArray.readBit()); - assertTrue(bitArray.readBit()); assertFalse(bitArray.readBit()); assertTrue(bitArray.readBit()); assertFalse(bitArray.readBit()); - - try { - assertFalse(bitArray.readBit()); - fail(); - } catch (IllegalStateException e) {/* ignored */} } public void testSkipBits() { VorbisBitArray bitArray = new VorbisBitArray(TestUtil.createByteArray(0xF0, 0x0F)); - bitArray.skipBits(10); assertEquals(10, bitArray.getPosition()); assertTrue(bitArray.readBit()); @@ -64,27 +54,10 @@ public final class VorbisBitArrayTest extends TestCase { assertEquals(14, bitArray.getPosition()); assertFalse(bitArray.readBit()); assertFalse(bitArray.readBit()); - try { - bitArray.readBit(); - fail(); - } catch (IllegalStateException e) { - // ignored - } - } - - - public void testSkipBitsThrowsErrorIfEOB() { - VorbisBitArray bitArray = new VorbisBitArray(TestUtil.createByteArray(0xF0, 0x0F)); - - try { - bitArray.skipBits(17); - fail(); - } catch (IllegalStateException e) {/* ignored */} } public void testGetPosition() throws Exception { VorbisBitArray bitArray = new VorbisBitArray(TestUtil.createByteArray(0xF0, 0x0F)); - assertEquals(0, bitArray.getPosition()); bitArray.readBit(); assertEquals(1, bitArray.getPosition()); @@ -96,35 +69,11 @@ public final class VorbisBitArrayTest extends TestCase { public void testSetPosition() throws Exception { VorbisBitArray bitArray = new VorbisBitArray(TestUtil.createByteArray(0xF0, 0x0F)); - assertEquals(0, bitArray.getPosition()); bitArray.setPosition(4); assertEquals(4, bitArray.getPosition()); - bitArray.setPosition(15); assertFalse(bitArray.readBit()); - try { - bitArray.readBit(); - fail(); - } catch (IllegalStateException e) {/* ignored */} - - } - public void testSetPositionIllegalPositions() throws Exception { - VorbisBitArray bitArray = new VorbisBitArray(TestUtil.createByteArray(0xF0, 0x0F)); - - try { - bitArray.setPosition(16); - fail(); - } catch (IllegalArgumentException e) { - assertEquals(0, bitArray.getPosition()); - } - - try { - bitArray.setPosition(-1); - fail(); - } catch (IllegalArgumentException e) { - assertEquals(0, bitArray.getPosition()); - } } public void testReadInt32() { @@ -136,13 +85,11 @@ public final class VorbisBitArrayTest extends TestCase { public void testReadBits() throws Exception { VorbisBitArray bitArray = new VorbisBitArray(TestUtil.createByteArray(0x03, 0x22)); - assertEquals(3, bitArray.readBits(2)); bitArray.skipBits(6); assertEquals(2, bitArray.readBits(2)); bitArray.skipBits(2); assertEquals(2, bitArray.readBits(2)); - bitArray.reset(); assertEquals(0x2203, bitArray.readBits(16)); } @@ -156,7 +103,6 @@ public final class VorbisBitArrayTest extends TestCase { public void testReadBitsBeyondByteBoundaries() throws Exception { VorbisBitArray bitArray = new VorbisBitArray(TestUtil.createByteArray(0xFF, 0x0F, 0xFF, 0x0F)); - assertEquals(0x0FFF0FFF, bitArray.readBits(32)); bitArray.reset(); @@ -188,83 +134,6 @@ public final class VorbisBitArrayTest extends TestCase { assertEquals(0, bitArray.getPosition()); bitArray.readBit(); assertEquals(1, bitArray.getPosition()); - - try { - bitArray.readBits(24); - fail(); - } catch (IllegalStateException e) { - assertEquals(1, bitArray.getPosition()); - } - } - - public void testLimit() { - VorbisBitArray bitArray = new VorbisBitArray(TestUtil.createByteArray(0xc0, 0x02), 1); - - try { - bitArray.skipBits(9); - fail(); - } catch (IllegalStateException e) { - assertEquals(0, bitArray.getPosition()); - } - - try { - bitArray.readBits(9); - fail(); - } catch (IllegalStateException e) { - assertEquals(0, bitArray.getPosition()); - } - - int byteValue = bitArray.readBits(8); - assertEquals(0xc0, byteValue); - assertEquals(8, bitArray.getPosition()); - try { - bitArray.readBit(); - fail(); - } catch (IllegalStateException e) { - assertEquals(8, bitArray.getPosition()); - } - } - - public void testBitsLeft() { - VorbisBitArray bitArray = new VorbisBitArray(TestUtil.createByteArray(0xc0, 0x02)); - - assertEquals(16, bitArray.bitsLeft()); - assertEquals(bitArray.limit(), bitArray.getPosition() + bitArray.bitsLeft()); - - bitArray.skipBits(1); - assertEquals(15, bitArray.bitsLeft()); - assertEquals(bitArray.limit(), bitArray.getPosition() + bitArray.bitsLeft()); - - bitArray.skipBits(3); - assertEquals(12, bitArray.bitsLeft()); - assertEquals(bitArray.limit(), bitArray.getPosition() + bitArray.bitsLeft()); - - bitArray.setPosition(6); - assertEquals(10, bitArray.bitsLeft()); - assertEquals(bitArray.limit(), bitArray.getPosition() + bitArray.bitsLeft()); - - bitArray.skipBits(1); - assertEquals(9, bitArray.bitsLeft()); - assertEquals(bitArray.limit(), bitArray.getPosition() + bitArray.bitsLeft()); - - bitArray.skipBits(1); - assertEquals(8, bitArray.bitsLeft()); - assertEquals(bitArray.limit(), bitArray.getPosition() + bitArray.bitsLeft()); - - bitArray.readBits(4); - assertEquals(4, bitArray.bitsLeft()); - assertEquals(bitArray.limit(), bitArray.getPosition() + bitArray.bitsLeft()); - - bitArray.readBits(4); - assertEquals(0, bitArray.bitsLeft()); - assertEquals(bitArray.limit(), bitArray.getPosition() + bitArray.bitsLeft()); - - try { - bitArray.readBit(); - fail(); - } catch (IllegalStateException e) { - assertEquals(0, bitArray.bitsLeft()); - } } } diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ogg/VorbisBitArray.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ogg/VorbisBitArray.java index ae52e80299..958a2ef955 100644 --- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ogg/VorbisBitArray.java +++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ogg/VorbisBitArray.java @@ -25,8 +25,9 @@ import com.google.android.exoplayer2.util.Assertions; */ /* package */ final class VorbisBitArray { - public final byte[] data; - private final int limit; + private final byte[] data; + private final int byteLimit; + private int byteOffset; private int bitOffset; @@ -36,18 +37,8 @@ import com.google.android.exoplayer2.util.Assertions; * @param data the array to wrap. */ public VorbisBitArray(byte[] data) { - this(data, data.length); - } - - /** - * Creates a new instance that wraps an existing array. - * - * @param data the array to wrap. - * @param limit the limit in bytes. - */ - public VorbisBitArray(byte[] data, int limit) { this.data = data; - this.limit = limit * 8; + byteLimit = data.length; } /** @@ -64,7 +55,9 @@ import com.google.android.exoplayer2.util.Assertions; * @return {@code true} if the bit is set, {@code false} otherwise. */ public boolean readBit() { - return readBits(1) == 1; + boolean returnValue = (((data[byteOffset] & 0xFF) >> bitOffset) & 0x01) == 1; + skipBits(1); + return returnValue; } /** @@ -74,53 +67,32 @@ import com.google.android.exoplayer2.util.Assertions; * @return An integer whose bottom {@code numBits} bits hold the read data. */ public int readBits(int numBits) { - Assertions.checkState(getPosition() + numBits <= limit); - if (numBits == 0) { - return 0; + int tempByteOffset = byteOffset; + int bitsRead = Math.min(numBits, 8 - bitOffset); + int returnValue = ((data[tempByteOffset++] & 0xFF) >> bitOffset) & (0xFF >> (8 - bitsRead)); + while (bitsRead < numBits) { + returnValue |= (data[tempByteOffset++] & 0xFF) << bitsRead; + bitsRead += 8; } - int result = 0; - int bitCount = 0; - if (bitOffset != 0) { - bitCount = Math.min(numBits, 8 - bitOffset); - int mask = 0xFF >>> (8 - bitCount); - result = (data[byteOffset] >>> bitOffset) & mask; - bitOffset += bitCount; - if (bitOffset == 8) { - byteOffset++; - bitOffset = 0; - } - } - - if (numBits - bitCount > 7) { - int numBytes = (numBits - bitCount) / 8; - for (int i = 0; i < numBytes; i++) { - result |= (data[byteOffset++] & 0xFFL) << bitCount; - bitCount += 8; - } - } - - if (numBits > bitCount) { - int bitsOnNextByte = numBits - bitCount; - int mask = 0xFF >>> (8 - bitsOnNextByte); - result |= (data[byteOffset] & mask) << bitCount; - bitOffset += bitsOnNextByte; - } - return result; + returnValue &= 0xFFFFFFFF >>> (32 - numBits); + skipBits(numBits); + return returnValue; } /** * Skips {@code numberOfBits} bits. * - * @param numberOfBits The number of bits to skip. + * @param numBits The number of bits to skip. */ - public void skipBits(int numberOfBits) { - Assertions.checkState(getPosition() + numberOfBits <= limit); - byteOffset += numberOfBits / 8; - bitOffset += numberOfBits % 8; + public void skipBits(int numBits) { + int numBytes = numBits / 8; + byteOffset += numBytes; + bitOffset += numBits - (numBytes * 8); if (bitOffset > 7) { byteOffset++; bitOffset -= 8; } + assertValidOffset(); } /** @@ -136,23 +108,22 @@ import com.google.android.exoplayer2.util.Assertions; * @param position The new reading position in bits. */ public void setPosition(int position) { - Assertions.checkArgument(position < limit && position >= 0); byteOffset = position / 8; bitOffset = position - (byteOffset * 8); + assertValidOffset(); } /** * Returns the number of remaining bits. */ public int bitsLeft() { - return limit - getPosition(); + return (byteLimit - byteOffset) * 8 - bitOffset; } - /** - * Returns the limit in bits. - **/ - public int limit() { - return limit; + private void assertValidOffset() { + // It is fine for position to be at the end of the array, but no further. + Assertions.checkState(byteOffset >= 0 + && (byteOffset < byteLimit || (byteOffset == byteLimit && bitOffset == 0))); } }