jdataview.js

//
// jDataView by Vjeux <vjeuxx@gmail.com> - Jan 2010
// Continued by RReverser <me@rreverser.com> - Feb 2013
//
// A unique way to work with a binary file in the browser
// http://github.com/jDataView/jDataView
// http://jDataView.github.io/

(function (global) {

'use strict';

var compatibility = {
	// NodeJS Buffer in v0.5.5 and newer
	NodeBuffer: 'Buffer' in global && 'readInt16LE' in Buffer.prototype,
	DataView: 'DataView' in global && (
		'getFloat64' in DataView.prototype ||            // Chrome
		'getFloat64' in new DataView(new ArrayBuffer(1)) // Node
	),
	ArrayBuffer: 'ArrayBuffer' in global,
	PixelData: 'CanvasPixelArray' in global && 'ImageData' in global && 'document' in global
};

// we don't want to bother with old Buffer implementation
if (compatibility.NodeBuffer) {
	(function (buffer) {
		try {
			buffer.writeFloatLE(Infinity, 0);
		} catch (e) {
			compatibility.NodeBuffer = false;
		}
	})(new Buffer(4));
}

if (compatibility.PixelData) {
	var createPixelData = function (byteLength, buffer) {
		var data = createPixelData.context2d.createImageData((byteLength + 3) / 4, 1).data;
		data.byteLength = byteLength;
		if (buffer !== undefined) {
			for (var i = 0; i < byteLength; i++) {
				data[i] = buffer[i];
			}
		}
		return data;
	};
	createPixelData.context2d = document.createElement('canvas').getContext('2d');
}

var dataTypes = {
	'Int8': 1,
	'Int16': 2,
	'Int32': 4,
	'Uint8': 1,
	'Uint16': 2,
	'Uint32': 4,
	'Float32': 4,
	'Float64': 8
};

var nodeNaming = {
	'Int8': 'Int8',
	'Int16': 'Int16',
	'Int32': 'Int32',
	'Uint8': 'UInt8',
	'Uint16': 'UInt16',
	'Uint32': 'UInt32',
	'Float32': 'Float',
	'Float64': 'Double'
};

function arrayFrom(arrayLike, forceCopy) {
	return (!forceCopy && (arrayLike instanceof Array)) ? arrayLike : Array.prototype.slice.call(arrayLike);
}

function defined(value, defaultValue) {
	return value !== undefined ? value : defaultValue;
}

function jDataView(buffer, byteOffset, byteLength, littleEndian) {
	/* jshint validthis:true */

	if (buffer instanceof jDataView) {
		var result = buffer.slice(byteOffset, byteOffset + byteLength);
		result._littleEndian = defined(littleEndian, result._littleEndian);
		return result;
	}

	if (!(this instanceof jDataView)) {
		return new jDataView(buffer, byteOffset, byteLength, littleEndian);
	}

	this.buffer = buffer = jDataView.wrapBuffer(buffer);

	// Check parameters and existing functionnalities
	this._isArrayBuffer = compatibility.ArrayBuffer && buffer instanceof ArrayBuffer;
	this._isPixelData = compatibility.PixelData && buffer instanceof CanvasPixelArray;
	this._isDataView = compatibility.DataView && this._isArrayBuffer;
	this._isNodeBuffer = compatibility.NodeBuffer && buffer instanceof Buffer;

	// Handle Type Errors
	if (!this._isNodeBuffer && !this._isArrayBuffer && !this._isPixelData && !(buffer instanceof Array)) {
		throw new TypeError('jDataView buffer has an incompatible type');
	}

	// Default Values
	this._littleEndian = !!littleEndian;

	var bufferLength = 'byteLength' in buffer ? buffer.byteLength : buffer.length;
	this.byteOffset = byteOffset = defined(byteOffset, 0);
	this.byteLength = byteLength = defined(byteLength, bufferLength - byteOffset);

	if (!this._isDataView) {
		this._checkBounds(byteOffset, byteLength, bufferLength);
	} else {
		this._view = new DataView(buffer, byteOffset, byteLength);
	}

	// Create uniform methods (action wrappers) for the following data types

	this._engineAction =
		this._isDataView
			? this._dataViewAction
		: this._isNodeBuffer
			? this._nodeBufferAction
		: this._isArrayBuffer
			? this._arrayBufferAction
		: this._arrayAction;
}

function getCharCodes(string) {
	if (compatibility.NodeBuffer) {
		return new Buffer(string, 'binary');
	}

	var Type = compatibility.ArrayBuffer ? Uint8Array : Array,
		codes = new Type(string.length);

	for (var i = 0, length = string.length; i < length; i++) {
		codes[i] = string.charCodeAt(i) & 0xff;
	}
	return codes;
}

// mostly internal function for wrapping any supported input (String or Array-like) to best suitable buffer format
jDataView.wrapBuffer = function (buffer) {
	switch (typeof buffer) {
		case 'number':
			if (compatibility.NodeBuffer) {
				buffer = new Buffer(buffer);
				buffer.fill(0);
			} else
			if (compatibility.ArrayBuffer) {
				buffer = new Uint8Array(buffer).buffer;
			} else
			if (compatibility.PixelData) {
				buffer = createPixelData(buffer);
			} else {
				buffer = new Array(buffer);
				for (var i = 0; i < buffer.length; i++) {
					buffer[i] = 0;
				}
			}
			return buffer;

		case 'string':
			buffer = getCharCodes(buffer);
			/* falls through */
		default:
			if ('length' in buffer && !((compatibility.NodeBuffer && buffer instanceof Buffer) || (compatibility.ArrayBuffer && buffer instanceof ArrayBuffer) || (compatibility.PixelData && buffer instanceof CanvasPixelArray))) {
				if (compatibility.NodeBuffer) {
					buffer = new Buffer(buffer);
				} else
				if (compatibility.ArrayBuffer) {
					if (!(buffer instanceof ArrayBuffer)) {
						buffer = new Uint8Array(buffer).buffer;
						// bug in Node.js <= 0.8:
						if (!(buffer instanceof ArrayBuffer)) {
							buffer = new Uint8Array(arrayFrom(buffer, true)).buffer;
						}
					}
				} else
				if (compatibility.PixelData) {
					buffer = createPixelData(buffer.length, buffer);
				} else {
					buffer = arrayFrom(buffer);
				}
			}
			return buffer;
	}
};

function pow2(n) {
	return (n >= 0 && n < 31) ? (1 << n) : (pow2[n] || (pow2[n] = Math.pow(2, n)));
}

// left for backward compatibility
jDataView.createBuffer = function () {
	return jDataView.wrapBuffer(arguments);
};

function Uint64(lo, hi) {
	this.lo = lo;
	this.hi = hi;
}

jDataView.Uint64 = Uint64;

Uint64.prototype = {
	valueOf: function () {
		return this.lo + pow2(32) * this.hi;
	},

	toString: function () {
		return Number.prototype.toString.apply(this.valueOf(), arguments);
	}
};

Uint64.fromNumber = function (number) {
	var hi = Math.floor(number / pow2(32)),
		lo = number - hi * pow2(32);

	return new Uint64(lo, hi);
};

function Int64(lo, hi) {
	Uint64.apply(this, arguments);
}

jDataView.Int64 = Int64;

Int64.prototype = 'create' in Object ? Object.create(Uint64.prototype) : new Uint64();

Int64.prototype.valueOf = function () {
	if (this.hi < pow2(31)) {
		return Uint64.prototype.valueOf.apply(this, arguments);
	}
	return -((pow2(32) - this.lo) + pow2(32) * (pow2(32) - 1 - this.hi));
};

Int64.fromNumber = function (number) {
	var lo, hi;
	if (number >= 0) {
		var unsigned = Uint64.fromNumber(number);
		lo = unsigned.lo;
		hi = unsigned.hi;
	} else {
		hi = Math.floor(number / pow2(32));
		lo = number - hi * pow2(32);
		hi += pow2(32);
	}
	return new Int64(lo, hi);
};

jDataView.prototype = {
	_offset: 0,
	_bitOffset: 0,

	compatibility: compatibility,

	_checkBounds: function (byteOffset, byteLength, maxLength) {
		// Do additional checks to simulate DataView
		if (typeof byteOffset !== 'number') {
			throw new TypeError('Offset is not a number.');
		}
		if (typeof byteLength !== 'number') {
			throw new TypeError('Size is not a number.');
		}
		if (byteLength < 0) {
			throw new RangeError('Length is negative.');
		}
		if (byteOffset < 0 || byteOffset + byteLength > defined(maxLength, this.byteLength)) {
			throw new RangeError('Offsets are out of bounds.');
		}
	},

	_action: function (type, isReadAction, byteOffset, littleEndian, value) {
		return this._engineAction(
			type,
			isReadAction,
			defined(byteOffset, this._offset),
			defined(littleEndian, this._littleEndian),
			value
		);
	},

	_dataViewAction: function (type, isReadAction, byteOffset, littleEndian, value) {
		// Move the internal offset forward
		this._offset = byteOffset + dataTypes[type];
		return isReadAction ? this._view['get' + type](byteOffset, littleEndian) : this._view['set' + type](byteOffset, value, littleEndian);
	},

	_nodeBufferAction: function (type, isReadAction, byteOffset, littleEndian, value) {
		// Move the internal offset forward
		this._offset = byteOffset + dataTypes[type];
		var nodeName = nodeNaming[type] + ((type === 'Int8' || type === 'Uint8') ? '' : littleEndian ? 'LE' : 'BE');
		byteOffset += this.byteOffset;
		return isReadAction ? this.buffer['read' + nodeName](byteOffset) : this.buffer['write' + nodeName](value, byteOffset);
	},

	_arrayBufferAction: function (type, isReadAction, byteOffset, littleEndian, value) {
		var size = dataTypes[type], TypedArray = global[type + 'Array'], typedArray;

		littleEndian = defined(littleEndian, this._littleEndian);

		// ArrayBuffer: we use a typed array of size 1 from original buffer if alignment is good and from slice when it's not
		if (size === 1 || ((this.byteOffset + byteOffset) % size === 0 && littleEndian)) {
			typedArray = new TypedArray(this.buffer, this.byteOffset + byteOffset, 1);
			this._offset = byteOffset + size;
			return isReadAction ? typedArray[0] : (typedArray[0] = value);
		} else {
			var bytes = new Uint8Array(isReadAction ? this.getBytes(size, byteOffset, littleEndian, true) : size);
			typedArray = new TypedArray(bytes.buffer, 0, 1);

			if (isReadAction) {
				return typedArray[0];
			} else {
				typedArray[0] = value;
				this._setBytes(byteOffset, bytes, littleEndian);
			}
		}
	},

	_arrayAction: function (type, isReadAction, byteOffset, littleEndian, value) {
		return isReadAction ? this['_get' + type](byteOffset, littleEndian) : this['_set' + type](byteOffset, value, littleEndian);
	},

	// Helpers

	_getBytes: function (length, byteOffset, littleEndian) {
		littleEndian = defined(littleEndian, this._littleEndian);
		byteOffset = defined(byteOffset, this._offset);
		length = defined(length, this.byteLength - byteOffset);

		this._checkBounds(byteOffset, length);

		byteOffset += this.byteOffset;

		this._offset = byteOffset - this.byteOffset + length;

		var result = this._isArrayBuffer
					 ? new Uint8Array(this.buffer, byteOffset, length)
					 : (this.buffer.slice || Array.prototype.slice).call(this.buffer, byteOffset, byteOffset + length);

		return littleEndian || length <= 1 ? result : arrayFrom(result).reverse();
	},

	// wrapper for external calls (do not return inner buffer directly to prevent it's modifying)
	getBytes: function (length, byteOffset, littleEndian, toArray) {
		var result = this._getBytes(length, byteOffset, defined(littleEndian, true));
		return toArray ? arrayFrom(result) : result;
	},

	_setBytes: function (byteOffset, bytes, littleEndian) {
		var length = bytes.length;

		// needed for Opera
		if (length === 0) {
			return;
		}

		littleEndian = defined(littleEndian, this._littleEndian);
		byteOffset = defined(byteOffset, this._offset);

		this._checkBounds(byteOffset, length);

		if (!littleEndian && length > 1) {
			bytes = arrayFrom(bytes, true).reverse();
		}

		byteOffset += this.byteOffset;

		if (this._isArrayBuffer) {
			new Uint8Array(this.buffer, byteOffset, length).set(bytes);
		}
		else {
			if (this._isNodeBuffer) {
				new Buffer(bytes).copy(this.buffer, byteOffset);
			} else {
				for (var i = 0; i < length; i++) {
					this.buffer[byteOffset + i] = bytes[i];
				}
			}
		}

		this._offset = byteOffset - this.byteOffset + length;
	},

	setBytes: function (byteOffset, bytes, littleEndian) {
		this._setBytes(byteOffset, bytes, defined(littleEndian, true));
	},

	getString: function (byteLength, byteOffset, encoding) {
		if (this._isNodeBuffer) {
			byteOffset = defined(byteOffset, this._offset);
			byteLength = defined(byteLength, this.byteLength - byteOffset);

			this._checkBounds(byteOffset, byteLength);

			this._offset = byteOffset + byteLength;
			return this.buffer.toString(encoding || 'binary', this.byteOffset + byteOffset, this.byteOffset + this._offset);
		}
		var bytes = this._getBytes(byteLength, byteOffset, true), string = '';
		byteLength = bytes.length;
		for (var i = 0; i < byteLength; i++) {
			string += String.fromCharCode(bytes[i]);
		}
		if (encoding === 'utf8') {
			string = decodeURIComponent(escape(string));
		}
		return string;
	},

	setString: function (byteOffset, subString, encoding) {
		if (this._isNodeBuffer) {
			byteOffset = defined(byteOffset, this._offset);
			this._checkBounds(byteOffset, subString.length);
			this._offset = byteOffset + this.buffer.write(subString, this.byteOffset + byteOffset, encoding || 'binary');
			return;
		}
		if (encoding === 'utf8') {
			subString = unescape(encodeURIComponent(subString));
		}
		this._setBytes(byteOffset, getCharCodes(subString), true);
	},

	getChar: function (byteOffset) {
		return this.getString(1, byteOffset);
	},

	setChar: function (byteOffset, character) {
		this.setString(byteOffset, character);
	},

	tell: function () {
		return this._offset;
	},

	seek: function (byteOffset) {
		this._checkBounds(byteOffset, 0);
		/* jshint boss: true */
		return this._offset = byteOffset;
	},

	skip: function (byteLength) {
		return this.seek(this._offset + byteLength);
	},

	slice: function (start, end, forceCopy) {
		function normalizeOffset(offset, byteLength) {
			return offset < 0 ? offset + byteLength : offset;
		}

		start = normalizeOffset(start, this.byteLength);
		end = normalizeOffset(defined(end, this.byteLength), this.byteLength);

		return forceCopy
			   ? new jDataView(this.getBytes(end - start, start, true, true), undefined, undefined, this._littleEndian)
			   : new jDataView(this.buffer, this.byteOffset + start, end - start, this._littleEndian);
	},

	alignBy: function (byteCount) {
		this._bitOffset = 0;
		if (defined(byteCount, 1) !== 1) {
			return this.skip(byteCount - (this._offset % byteCount || byteCount));
		} else {
			return this._offset;
		}
	},

	// Compatibility functions

	_getFloat64: function (byteOffset, littleEndian) {
		var b = this._getBytes(8, byteOffset, littleEndian),

			sign = 1 - (2 * (b[7] >> 7)),
			exponent = ((((b[7] << 1) & 0xff) << 3) | (b[6] >> 4)) - ((1 << 10) - 1),

		// Binary operators such as | and << operate on 32 bit values, using + and Math.pow(2) instead
			mantissa = ((b[6] & 0x0f) * pow2(48)) + (b[5] * pow2(40)) + (b[4] * pow2(32)) +
						(b[3] * pow2(24)) + (b[2] * pow2(16)) + (b[1] * pow2(8)) + b[0];

		if (exponent === 1024) {
			if (mantissa !== 0) {
				return NaN;
			} else {
				return sign * Infinity;
			}
		}

		if (exponent === -1023) { // Denormalized
			return sign * mantissa * pow2(-1022 - 52);
		}

		return sign * (1 + mantissa * pow2(-52)) * pow2(exponent);
	},

	_getFloat32: function (byteOffset, littleEndian) {
		var b = this._getBytes(4, byteOffset, littleEndian),

			sign = 1 - (2 * (b[3] >> 7)),
			exponent = (((b[3] << 1) & 0xff) | (b[2] >> 7)) - 127,
			mantissa = ((b[2] & 0x7f) << 16) | (b[1] << 8) | b[0];

		if (exponent === 128) {
			if (mantissa !== 0) {
				return NaN;
			} else {
				return sign * Infinity;
			}
		}

		if (exponent === -127) { // Denormalized
			return sign * mantissa * pow2(-126 - 23);
		}

		return sign * (1 + mantissa * pow2(-23)) * pow2(exponent);
	},

	_get64: function (Type, byteOffset, littleEndian) {
		littleEndian = defined(littleEndian, this._littleEndian);
		byteOffset = defined(byteOffset, this._offset);

		var parts = littleEndian ? [0, 4] : [4, 0];

		for (var i = 0; i < 2; i++) {
			parts[i] = this.getUint32(byteOffset + parts[i], littleEndian);
		}

		this._offset = byteOffset + 8;

		return new Type(parts[0], parts[1]);
	},

	getInt64: function (byteOffset, littleEndian) {
		return this._get64(Int64, byteOffset, littleEndian);
	},

	getUint64: function (byteOffset, littleEndian) {
		return this._get64(Uint64, byteOffset, littleEndian);
	},

	_getInt32: function (byteOffset, littleEndian) {
		var b = this._getBytes(4, byteOffset, littleEndian);
		return (b[3] << 24) | (b[2] << 16) | (b[1] << 8) | b[0];
	},

	_getUint32: function (byteOffset, littleEndian) {
		return this._getInt32(byteOffset, littleEndian) >>> 0;
	},

	_getInt16: function (byteOffset, littleEndian) {
		return (this._getUint16(byteOffset, littleEndian) << 16) >> 16;
	},

	_getUint16: function (byteOffset, littleEndian) {
		var b = this._getBytes(2, byteOffset, littleEndian);
		return (b[1] << 8) | b[0];
	},

	_getInt8: function (byteOffset) {
		return (this._getUint8(byteOffset) << 24) >> 24;
	},

	_getUint8: function (byteOffset) {
		return this._getBytes(1, byteOffset)[0];
	},

	_getBitRangeData: function (bitLength, byteOffset) {
		var startBit = (defined(byteOffset, this._offset) << 3) + this._bitOffset,
			endBit = startBit + bitLength,
			start = startBit >>> 3,
			end = (endBit + 7) >>> 3,
			b = this._getBytes(end - start, start, true),
			wideValue = 0;

		/* jshint boss: true */
		if (this._bitOffset = endBit & 7) {
			this._bitOffset -= 8;
		}

		for (var i = 0, length = b.length; i < length; i++) {
			wideValue = (wideValue << 8) | b[i];
		}

		return {
			start: start,
			bytes: b,
			wideValue: wideValue
		};
	},

	getSigned: function (bitLength, byteOffset) {
		var shift = 32 - bitLength;
		return (this.getUnsigned(bitLength, byteOffset) << shift) >> shift;
	},

	getUnsigned: function (bitLength, byteOffset) {
		var value = this._getBitRangeData(bitLength, byteOffset).wideValue >>> -this._bitOffset;
		return bitLength < 32 ? (value & ~(-1 << bitLength)) : value;
	},

	_setBinaryFloat: function (byteOffset, value, mantSize, expSize, littleEndian) {
		var signBit = value < 0 ? 1 : 0,
			exponent,
			mantissa,
			eMax = ~(-1 << (expSize - 1)),
			eMin = 1 - eMax;

		if (value < 0) {
			value = -value;
		}

		if (value === 0) {
			exponent = 0;
			mantissa = 0;
		} else if (isNaN(value)) {
			exponent = 2 * eMax + 1;
			mantissa = 1;
		} else if (value === Infinity) {
			exponent = 2 * eMax + 1;
			mantissa = 0;
		} else {
			exponent = Math.floor(Math.log(value) / Math.LN2);
			if (exponent >= eMin && exponent <= eMax) {
				mantissa = Math.floor((value * pow2(-exponent) - 1) * pow2(mantSize));
				exponent += eMax;
			} else {
				mantissa = Math.floor(value / pow2(eMin - mantSize));
				exponent = 0;
			}
		}

		var b = [];
		while (mantSize >= 8) {
			b.push(mantissa % 256);
			mantissa = Math.floor(mantissa / 256);
			mantSize -= 8;
		}
		exponent = (exponent << mantSize) | mantissa;
		expSize += mantSize;
		while (expSize >= 8) {
			b.push(exponent & 0xff);
			exponent >>>= 8;
			expSize -= 8;
		}
		b.push((signBit << expSize) | exponent);

		this._setBytes(byteOffset, b, littleEndian);
	},

	_setFloat32: function (byteOffset, value, littleEndian) {
		this._setBinaryFloat(byteOffset, value, 23, 8, littleEndian);
	},

	_setFloat64: function (byteOffset, value, littleEndian) {
		this._setBinaryFloat(byteOffset, value, 52, 11, littleEndian);
	},

	_set64: function (Type, byteOffset, value, littleEndian) {
		if (!(value instanceof Type)) {
			value = Type.fromNumber(value);
		}

		littleEndian = defined(littleEndian, this._littleEndian);
		byteOffset = defined(byteOffset, this._offset);

		var parts = littleEndian ? {lo: 0, hi: 4} : {lo: 4, hi: 0};

		for (var partName in parts) {
			this.setUint32(byteOffset + parts[partName], value[partName], littleEndian);
		}

		this._offset = byteOffset + 8;
	},

	setInt64: function (byteOffset, value, littleEndian) {
		this._set64(Int64, byteOffset, value, littleEndian);
	},

	setUint64: function (byteOffset, value, littleEndian) {
		this._set64(Uint64, byteOffset, value, littleEndian);
	},

	_setUint32: function (byteOffset, value, littleEndian) {
		this._setBytes(byteOffset, [
			value & 0xff,
			(value >>> 8) & 0xff,
			(value >>> 16) & 0xff,
			value >>> 24
		], littleEndian);
	},

	_setUint16: function (byteOffset, value, littleEndian) {
		this._setBytes(byteOffset, [
			value & 0xff,
			(value >>> 8) & 0xff
		], littleEndian);
	},

	_setUint8: function (byteOffset, value) {
		this._setBytes(byteOffset, [value & 0xff]);
	},

	setUnsigned: function (byteOffset, value, bitLength) {
		var data = this._getBitRangeData(bitLength, byteOffset),
			wideValue = data.wideValue,
			b = data.bytes;

		wideValue &= ~(~(-1 << bitLength) << -this._bitOffset); // clearing bit range before binary "or"
		wideValue |= (bitLength < 32 ? (value & ~(-1 << bitLength)) : value) << -this._bitOffset; // setting bits

		for (var i = b.length - 1; i >= 0; i--) {
			b[i] = wideValue & 0xff;
			wideValue >>>= 8;
		}

		this._setBytes(data.start, b, true);
	}
};

var proto = jDataView.prototype;

for (var type in dataTypes) {
	(function (type) {
		proto['get' + type] = function (byteOffset, littleEndian) {
			return this._action(type, true, byteOffset, littleEndian);
		};
		proto['set' + type] = function (byteOffset, value, littleEndian) {
			this._action(type, false, byteOffset, littleEndian, value);
		};
	})(type);
}

proto._setInt32 = proto._setUint32;
proto._setInt16 = proto._setUint16;
proto._setInt8 = proto._setUint8;
proto.setSigned = proto.setUnsigned;

for (var method in proto) {
	if (method.slice(0, 3) === 'set') {
		(function (type) {
			proto['write' + type] = function () {
				Array.prototype.unshift.call(arguments, undefined);
				this['set' + type].apply(this, arguments);
			};
		})(method.slice(3));
	}
}

if (typeof module !== 'undefined' && typeof module.exports === 'object') {
	module.exports = jDataView;
} else
if (typeof define === 'function' && define.amd) {
	define([], function () { return jDataView });
} else {
	var oldGlobal = global.jDataView;
	(global.jDataView = jDataView).noConflict = function () {
		global.jDataView = oldGlobal;
		return this;
	};
}

})((function () { /* jshint strict: false */ return this })());