/**
* @license
* Copyright 2016 Google Inc.
*
* 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.
*/
goog.provide('shaka.util.DataViewReader');
goog.require('goog.asserts');
goog.require('shaka.util.Error');
goog.require('shaka.util.StringUtils');
/**
* Creates a DataViewReader, which abstracts a DataView object.
*
* @param {!DataView} dataView The DataView.
* @param {shaka.util.DataViewReader.Endianness} endianness The endianness.
*
* @struct
* @constructor
* @export
*/
shaka.util.DataViewReader = function(dataView, endianness) {
/** @private {!DataView} */
this.dataView_ = dataView;
/** @private {boolean} */
this.littleEndian_ =
endianness == shaka.util.DataViewReader.Endianness.LITTLE_ENDIAN;
/** @private {number} */
this.position_ = 0;
};
/**
* Endianness.
* @enum {number}
* @export
*/
shaka.util.DataViewReader.Endianness = {
BIG_ENDIAN: 0,
LITTLE_ENDIAN: 1
};
/**
* @return {boolean} True if the reader has more data, false otherwise.
* @export
*/
shaka.util.DataViewReader.prototype.hasMoreData = function() {
return this.position_ < this.dataView_.byteLength;
};
/**
* Gets the current byte position.
* @return {number}
* @export
*/
shaka.util.DataViewReader.prototype.getPosition = function() {
return this.position_;
};
/**
* Gets the byte length of the DataView.
* @return {number}
* @export
*/
shaka.util.DataViewReader.prototype.getLength = function() {
return this.dataView_.byteLength;
};
/**
* Reads an unsigned 8 bit integer, and advances the reader.
* @return {number} The integer.
* @throws {shaka.util.Error} when reading past the end of the data view.
* @export
*/
shaka.util.DataViewReader.prototype.readUint8 = function() {
try {
let value = this.dataView_.getUint8(this.position_);
this.position_ += 1;
return value;
} catch (exception) {
this.throwOutOfBounds_();
}
};
/**
* Reads an unsigned 16 bit integer, and advances the reader.
* @return {number} The integer.
* @throws {shaka.util.Error} when reading past the end of the data view.
* @export
*/
shaka.util.DataViewReader.prototype.readUint16 = function() {
try {
let value = this.dataView_.getUint16(this.position_, this.littleEndian_);
this.position_ += 2;
return value;
} catch (exception) {
this.throwOutOfBounds_();
}
};
/**
* Reads an unsigned 32 bit integer, and advances the reader.
* @return {number} The integer.
* @throws {shaka.util.Error} when reading past the end of the data view.
* @export
*/
shaka.util.DataViewReader.prototype.readUint32 = function() {
try {
let value = this.dataView_.getUint32(this.position_, this.littleEndian_);
this.position_ += 4;
return value;
} catch (exception) {
this.throwOutOfBounds_();
}
};
/**
* Reads a signed 32 bit integer, and advances the reader.
* @return {number} The integer.
* @throws {shaka.util.Error} when reading past the end of the data view.
* @export
*/
shaka.util.DataViewReader.prototype.readInt32 = function() {
try {
let value = this.dataView_.getInt32(this.position_, this.littleEndian_);
this.position_ += 4;
return value;
} catch (exception) {
this.throwOutOfBounds_();
}
};
/**
* Reads an unsigned 64 bit integer, and advances the reader.
* @return {number} The integer.
* @throws {shaka.util.Error} when reading past the end of the data view or
* when reading an integer too large to store accurately in JavaScript.
* @export
*/
shaka.util.DataViewReader.prototype.readUint64 = function() {
let low, high;
try {
if (this.littleEndian_) {
low = this.dataView_.getUint32(this.position_, true);
high = this.dataView_.getUint32(this.position_ + 4, true);
} else {
high = this.dataView_.getUint32(this.position_, false);
low = this.dataView_.getUint32(this.position_ + 4, false);
}
} catch (exception) {
this.throwOutOfBounds_();
}
if (high > 0x1FFFFF) {
throw new shaka.util.Error(
shaka.util.Error.Severity.CRITICAL,
shaka.util.Error.Category.MEDIA,
shaka.util.Error.Code.JS_INTEGER_OVERFLOW);
}
this.position_ += 8;
// NOTE: This is subtle, but in JavaScript you can't shift left by 32 and get
// the full range of 53-bit values possible. You must multiply by 2^32.
return (high * Math.pow(2, 32)) + low;
};
/**
* Reads the specified number of raw bytes.
* @param {number} bytes The number of bytes to read.
* @return {!Uint8Array}
* @throws {shaka.util.Error} when reading past the end of the data view.
* @export
*/
shaka.util.DataViewReader.prototype.readBytes = function(bytes) {
goog.asserts.assert(bytes > 0, 'Bad call to DataViewReader.readBytes');
if (this.position_ + bytes > this.dataView_.byteLength) {
this.throwOutOfBounds_();
}
let value = new Uint8Array(
this.dataView_.buffer, this.dataView_.byteOffset + this.position_, bytes);
this.position_ += bytes;
return new Uint8Array(value);
};
/**
* Skips the specified number of bytes.
* @param {number} bytes The number of bytes to skip.
* @throws {shaka.util.Error} when skipping past the end of the data view.
* @export
*/
shaka.util.DataViewReader.prototype.skip = function(bytes) {
goog.asserts.assert(bytes >= 0, 'Bad call to DataViewReader.skip');
if (this.position_ + bytes > this.dataView_.byteLength) {
this.throwOutOfBounds_();
}
this.position_ += bytes;
};
/**
* Rewinds the specified number of bytes.
* @param {number} bytes The number of bytes to rewind.
* @throws {shaka.util.Error} when rewinding past the beginning of the data
* view.
* @export
*/
shaka.util.DataViewReader.prototype.rewind = function(bytes) {
goog.asserts.assert(bytes >= 0, 'Bad call to DataViewReader.rewind');
if (this.position_ < bytes) {
this.throwOutOfBounds_();
}
this.position_ -= bytes;
};
/**
* Seeks to a specified position.
* @param {number} position The desired byte position within the DataView.
* @throws {shaka.util.Error} when seeking outside the range of the data view.
* @export
*/
shaka.util.DataViewReader.prototype.seek = function(position) {
goog.asserts.assert(position >= 0, 'Bad call to DataViewReader.seek');
if (position < 0 || position > this.dataView_.byteLength) {
this.throwOutOfBounds_();
}
this.position_ = position;
};
/**
* Keeps reading until it reaches a byte that equals to zero. The text is
* assumed to be UTF-8.
* @return {string}
* @export
*/
shaka.util.DataViewReader.prototype.readTerminatedString = function() {
let start = this.position_;
while (this.hasMoreData()) {
let value = this.dataView_.getUint8(this.position_);
if (value == 0) break;
this.position_ += 1;
}
let ret = new Uint8Array(
this.dataView_.buffer, this.dataView_.byteOffset + start,
this.position_ - start);
// Skip string termination.
this.position_ += 1;
return shaka.util.StringUtils.fromUTF8(ret);
};
/**
* @throws {shaka.util.Error}
* @private
*/
shaka.util.DataViewReader.prototype.throwOutOfBounds_ = function() {
throw new shaka.util.Error(
shaka.util.Error.Severity.CRITICAL,
shaka.util.Error.Category.MEDIA,
shaka.util.Error.Code.BUFFER_READ_OUT_OF_BOUNDS);
};