/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.media3.common.util;
import androidx.annotation.Nullable;
import com.google.common.base.Charsets;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.util.Arrays;
/**
* Wraps a byte array, providing a set of methods for parsing data from it. Numerical values are
* parsed with the assumption that their constituent bytes are in big endian order.
*/
@UnstableApi
public final class ParsableByteArray {
private byte[] data;
private int position;
// TODO(internal b/147657250): Enforce this limit on all read methods.
private int limit;
/** Creates a new instance that initially has no backing data. */
public ParsableByteArray() {
data = Util.EMPTY_BYTE_ARRAY;
}
/**
* Creates a new instance with {@code limit} bytes and sets the limit.
*
* @param limit The limit to set.
*/
public ParsableByteArray(int limit) {
this.data = new byte[limit];
this.limit = limit;
}
/**
* Creates a new instance wrapping {@code data}, and sets the limit to {@code data.length}.
*
* @param data The array to wrap.
*/
public ParsableByteArray(byte[] data) {
this.data = data;
limit = data.length;
}
/**
* Creates a new instance that wraps an existing array.
*
* @param data The data to wrap.
* @param limit The limit to set.
*/
public ParsableByteArray(byte[] data, int limit) {
this.data = data;
this.limit = limit;
}
/**
* Resets the position to zero and the limit to the specified value. This might replace or wipe
* the {@link #getData() underlying array}, potentially invalidating any local references.
*
* @param limit The limit to set.
*/
public void reset(int limit) {
reset(capacity() < limit ? new byte[limit] : data, limit);
}
/**
* Updates the instance to wrap {@code data}, and resets the position to zero and the limit to
* {@code data.length}.
*
* @param data The array to wrap.
*/
public void reset(byte[] data) {
reset(data, data.length);
}
/**
* Updates the instance to wrap {@code data}, and resets the position to zero.
*
* @param data The array to wrap.
* @param limit The limit to set.
*/
public void reset(byte[] data, int limit) {
this.data = data;
this.limit = limit;
position = 0;
}
/**
* Ensures the backing array is at least {@code requiredCapacity} long.
*
* <p>{@link #getPosition() position}, {@link #limit() limit}, and all data in the underlying
* array (including that beyond {@link #limit()}) are preserved.
*
* <p>This might replace or wipe the {@link #getData() underlying array}, potentially invalidating
* any local references.
*/
public void ensureCapacity(int requiredCapacity) {
if (requiredCapacity > capacity()) {
data = Arrays.copyOf(data, requiredCapacity);
}
}
/** Returns the number of bytes yet to be read. */
public int bytesLeft() {
return limit - position;
}
/** Returns the limit. */
public int limit() {
return limit;
}
/**
* Sets the limit.
*
* @param limit The limit to set.
*/
public void setLimit(int limit) {
Assertions.checkArgument(limit >= 0 && limit <= data.length);
this.limit = limit;
}
/** Returns the current offset in the array, in bytes. */
public int getPosition() {
return position;
}
/**
* Sets the reading offset in the array.
*
* @param position Byte offset in the array from which to read.
* @throws IllegalArgumentException Thrown if the new position is neither in nor at the end of the
* array.
*/
public void setPosition(int position) {
// It is fine for position to be at the end of the array.
Assertions.checkArgument(position >= 0 && position <= limit);
this.position = position;
}
/**
* Returns the underlying array.
*
* <p>Changes to this array are reflected in the results of the {@code read...()} methods.
*
* <p>This reference must be assumed to become invalid when {@link #reset} or {@link
* #ensureCapacity} are called (because the array might get reallocated).
*/
public byte[] getData() {
return data;
}
/** Returns the capacity of the array, which may be larger than the limit. */
public int capacity() {
return data.length;
}
/**
* Moves the reading offset by {@code bytes}.
*
* @param bytes The number of bytes to skip.
* @throws IllegalArgumentException Thrown if the new position is neither in nor at the end of the
* array.
*/
public void skipBytes(int bytes) {
setPosition(position + bytes);
}
/**
* Reads the next {@code length} bytes into {@code bitArray}, and resets the position of {@code
* bitArray} to zero.
*
* @param bitArray The {@link ParsableBitArray} into which the bytes should be read.
* @param length The number of bytes to write.
*/
public void readBytes(ParsableBitArray bitArray, int length) {
readBytes(bitArray.data, 0, length);
bitArray.setPosition(0);
}
/**
* Reads the next {@code length} bytes into {@code buffer} at {@code offset}.
*
* @see System#arraycopy(Object, int, Object, int, int)
* @param buffer The array into which the read data should be written.
* @param offset The offset in {@code buffer} at which the read data should be written.
* @param length The number of bytes to read.
*/
public void readBytes(byte[] buffer, int offset, int length) {
System.arraycopy(data, position, buffer, offset, length);
position += length;
}
/**
* Reads the next {@code length} bytes into {@code buffer}.
*
* @see ByteBuffer#put(byte[], int, int)
* @param buffer The {@link ByteBuffer} into which the read data should be written.
* @param length The number of bytes to read.
*/
public void readBytes(ByteBuffer buffer, int length) {
buffer.put(data, position, length);
position += length;
}
/** Peeks at the next byte as an unsigned value. */
public int peekUnsignedByte() {
return (data[position] & 0xFF);
}
/** Peeks at the next char. */
public char peekChar() {
return (char) ((data[position] & 0xFF) << 8 | (data[position + 1] & 0xFF));
}
/** Reads the next byte as an unsigned value. */
public int readUnsignedByte() {
return (data[position++] & 0xFF);
}
/** Reads the next two bytes as an unsigned value. */
public int readUnsignedShort() {
return (data[position++] & 0xFF) << 8 | (data[position++] & 0xFF);
}
/** Reads the next two bytes as an unsigned value. */
public int readLittleEndianUnsignedShort() {
return (data[position++] & 0xFF) | (data[position++] & 0xFF) << 8;
}
/** Reads the next two bytes as a signed value. */
public short readShort() {
return (short) ((data[position++] & 0xFF) << 8 | (data[position++] & 0xFF));
}
/** Reads the next two bytes as a signed value. */
public short readLittleEndianShort() {
return (short) ((data[position++] & 0xFF) | (data[position++] & 0xFF) << 8);
}
/** Reads the next three bytes as an unsigned value. */
public int readUnsignedInt24() {
return (data[position++] & 0xFF) << 16
| (data[position++] & 0xFF) << 8
| (data[position++] & 0xFF);
}
/** Reads the next three bytes as a signed value. */
public int readInt24() {
return ((data[position++] & 0xFF) << 24) >> 8
| (data[position++] & 0xFF) << 8
| (data[position++] & 0xFF);
}
/** Reads the next three bytes as a signed value in little endian order. */
public int readLittleEndianInt24() {
return (data[position++] & 0xFF)
| (data[position++] & 0xFF) << 8
| (data[position++] & 0xFF) << 16;
}
/** Reads the next three bytes as an unsigned value in little endian order. */
public int readLittleEndianUnsignedInt24() {
return (data[position++] & 0xFF)
| (data[position++] & 0xFF) << 8
| (data[position++] & 0xFF) << 16;
}
/** Reads the next four bytes as an unsigned value. */
public long readUnsignedInt() {
return (data[position++] & 0xFFL) << 24
| (data[position++] & 0xFFL) << 16
| (data[position++] & 0xFFL) << 8
| (data[position++] & 0xFFL);
}
/** Reads the next four bytes as an unsigned value in little endian order. */
public long readLittleEndianUnsignedInt() {
return (data[position++] & 0xFFL)
| (data[position++] & 0xFFL) << 8
| (data[position++] & 0xFFL) << 16
| (data[position++] & 0xFFL) << 24;
}
/** Reads the next four bytes as a signed value */
public int readInt() {
return (data[position++] & 0xFF) << 24
| (data[position++] & 0xFF) << 16
| (data[position++] & 0xFF) << 8
| (data[position++] & 0xFF);
}
/** Reads the next four bytes as a signed value in little endian order. */
public int readLittleEndianInt() {
return (data[position++] & 0xFF)
| (data[position++] & 0xFF) << 8
| (data[position++] & 0xFF) << 16
| (data[position++] & 0xFF) << 24;
}
/** Reads the next eight bytes as a signed value. */
public long readLong() {
return (data[position++] & 0xFFL) << 56
| (data[position++] & 0xFFL) << 48
| (data[position++] & 0xFFL) << 40
| (data[position++] & 0xFFL) << 32
| (data[position++] & 0xFFL) << 24
| (data[position++] & 0xFFL) << 16
| (data[position++] & 0xFFL) << 8
| (data[position++] & 0xFFL);
}
/** Reads the next eight bytes as a signed value in little endian order. */
public long readLittleEndianLong() {
return (data[position++] & 0xFFL)
| (data[position++] & 0xFFL) << 8
| (data[position++] & 0xFFL) << 16
| (data[position++] & 0xFFL) << 24
| (data[position++] & 0xFFL) << 32
| (data[position++] & 0xFFL) << 40
| (data[position++] & 0xFFL) << 48
| (data[position++] & 0xFFL) << 56;
}
/** Reads the next four bytes, returning the integer portion of the fixed point 16.16 integer. */
public int readUnsignedFixedPoint1616() {
int result = (data[position++] & 0xFF) << 8 | (data[position++] & 0xFF);
position += 2; // Skip the non-integer portion.
return result;
}
/**
* Reads a Synchsafe integer.
*
* <p>Synchsafe integers keep the highest bit of every byte zeroed. A 32 bit synchsafe integer can
* store 28 bits of information.
*
* @return The parsed value.
*/
public int readSynchSafeInt() {
int b1 = readUnsignedByte();
int b2 = readUnsignedByte();
int b3 = readUnsignedByte();
int b4 = readUnsignedByte();
return (b1 << 21) | (b2 << 14) | (b3 << 7) | b4;
}
/**
* Reads the next four bytes as an unsigned integer into an integer, if the top bit is a zero.
*
* @throws IllegalStateException Thrown if the top bit of the input data is set.
*/
public int readUnsignedIntToInt() {
int result = readInt();
if (result < 0) {
throw new IllegalStateException("Top bit not zero: " + result);
}
return result;
}
/**
* Reads the next four bytes as a little endian unsigned integer into an integer, if the top bit
* is a zero.
*
* @throws IllegalStateException Thrown if the top bit of the input data is set.
*/
public int readLittleEndianUnsignedIntToInt() {
int result = readLittleEndianInt();
if (result < 0) {
throw new IllegalStateException("Top bit not zero: " + result);
}
return result;
}
/**
* Reads the next eight bytes as an unsigned long into a long, if the top bit is a zero.
*
* @throws IllegalStateException Thrown if the top bit of the input data is set.
*/
public long readUnsignedLongToLong() {
long result = readLong();
if (result < 0) {
throw new IllegalStateException("Top bit not zero: " + result);
}
return result;
}
/** Reads the next four bytes as a 32-bit floating point value. */
public float readFloat() {
return Float.intBitsToFloat(readInt());
}
/** Reads the next eight bytes as a 64-bit floating point value. */
public double readDouble() {
return Double.longBitsToDouble(readLong());
}
/**
* Reads the next {@code length} bytes as UTF-8 characters.
*
* @param length The number of bytes to read.
* @return The string encoded by the bytes.
*/
public String readString(int length) {
return readString(length, Charsets.UTF_8);
}
/**
* Reads the next {@code length} bytes as characters in the specified {@link Charset}.
*
* @param length The number of bytes to read.
* @param charset The character set of the encoded characters.
* @return The string encoded by the bytes in the specified character set.
*/
public String readString(int length, Charset charset) {
String result = new String(data, position, length, charset);
position += length;
return result;
}
/**
* Reads the next {@code length} bytes as UTF-8 characters. A terminating NUL byte is discarded,
* if present.
*
* @param length The number of bytes to read.
* @return The string, not including any terminating NUL byte.
*/
public String readNullTerminatedString(int length) {
if (length == 0) {
return "";
}
int stringLength = length;
int lastIndex = position + length - 1;
if (lastIndex < limit && data[lastIndex] == 0) {
stringLength--;
}
String result = Util.fromUtf8Bytes(data, position, stringLength);
position += length;
return result;
}
/**
* Reads up to the next NUL byte (or the limit) as UTF-8 characters.
*
* @return The string not including any terminating NUL byte, or null if the end of the data has
* already been reached.
*/
@Nullable
public String readNullTerminatedString() {
return readDelimiterTerminatedString('eb3b9ed0-f11d-0137-cfb9-0ebaa35b92c0');
}
/**
* Reads up to the next delimiter byte (or the limit) as UTF-8 characters.
*
* @return The string not including any terminating delimiter byte, or null if the end of the data
* has already been reached.
*/
@Nullable
public String readDelimiterTerminatedString(char delimiter) {
if (bytesLeft() == 0) {
return null;
}
int stringLimit = position;
while (stringLimit < limit && data[stringLimit] != delimiter) {
stringLimit++;
}
String string = Util.fromUtf8Bytes(data, position, stringLimit - position);
position = stringLimit;
if (position < limit) {
position++;
}
return string;
}
/**
* Reads a line of text.
*
* <p>A line is considered to be terminated by any one of a carriage return ('\r'), a line feed
* ('\n'), or a carriage return followed immediately by a line feed ('\r\n'). The UTF-8 charset is
* used. This method discards leading UTF-8 byte order marks, if present.
*
* @return The line not including any line-termination characters, or null if the end of the data
* has already been reached.
*/
@Nullable
public String readLine() {
if (bytesLeft() == 0) {
return null;
}
int lineLimit = position;
while (lineLimit < limit && !Util.isLinebreak(data[lineLimit])) {
lineLimit++;
}
if (lineLimit - position >= 3
&& data[position] == (byte) 0xEF
&& data[position + 1] == (byte) 0xBB
&& data[position + 2] == (byte) 0xBF) {
// There's a UTF-8 byte order mark at the start of the line. Discard it.
position += 3;
}
String line = Util.fromUtf8Bytes(data, position, lineLimit - position);
position = lineLimit;
if (position == limit) {
return line;
}
if (data[position] == '\r') {
position++;
if (position == limit) {
return line;
}
}
if (data[position] == '\n') {
position++;
}
return line;
}
/**
* Reads a long value encoded by UTF-8 encoding
*
* @throws NumberFormatException if there is a problem with decoding
* @return Decoded long value
*/
public long readUtf8EncodedLong() {
int length = 0;
long value = data[position];
// find the high most 0 bit
for (int j = 7; j >= 0; j--) {
if ((value & (1 << j)) == 0) {
if (j < 6) {
value &= (1 << j) - 1;
length = 7 - j;
} else if (j == 7) {
length = 1;
}
break;
}
}
if (length == 0) {
throw new NumberFormatException("Invalid UTF-8 sequence first byte: " + value);
}
for (int i = 1; i < length; i++) {
int x = data[position + i];
if ((x & 0xC0) != 0x80) { // if the high most 0 bit not 7th
throw new NumberFormatException("Invalid UTF-8 sequence continuation byte: " + value);
}
value = (value << 6) | (x & 0x3F);
}
position += length;
return value;
}
}