jdataview.js

//
// jDataView by Vjeux - Jan 2010
//
// A unique way to read a binary file in the browser
// http://github.com/vjeux/jDataView
// http://blog.vjeux.com/ <vjeuxx@gmail.com>
//

(function (global) {

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

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'
};

var jDataView = function (buffer, byteOffset, byteLength, littleEndian) {
  if (!(this instanceof jDataView)) {
    throw new Error("jDataView constructor may not be called as a function");
  }

  this.buffer = buffer;

  // Handle Type Errors
  if (!(compatibility.NodeBuffer && buffer instanceof Buffer) &&
    !(compatibility.ArrayBuffer && buffer instanceof ArrayBuffer) &&
    typeof buffer !== 'string') {
    throw new TypeError('jDataView buffer has an incompatible type');
  }

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

  // Default Values
  this._littleEndian = littleEndian === undefined ? false : littleEndian;

  var bufferLength = this._isArrayBuffer ? buffer.byteLength : buffer.length;
  if (byteOffset === undefined) {
    byteOffset = 0;
  }
  this.byteOffset = byteOffset;

  if (byteLength === undefined) {
    byteLength = bufferLength - byteOffset;
  }
  this.byteLength = byteLength;

  if (!this._isDataView) {
    // Do additional checks to simulate DataView
    if (typeof byteOffset !== 'number') {
      throw new TypeError('jDataView byteOffset is not a number');
    }
    if (typeof byteLength !== 'number') {
      throw new TypeError('jDataView byteLength is not a number');
    }
    if (byteOffset < 0) {
      throw new Error('jDataView byteOffset is negative');
    }
    if (byteLength < 0) {
      throw new Error('jDataView byteLength is negative');
    }
  }

  // Instanciate
  if (this._isDataView) {
    this._view = new DataView(buffer, byteOffset, byteLength);
    this._start = 0;
  }
  this._start = byteOffset;
  if (byteOffset + byteLength > bufferLength) {
    throw new Error("jDataView (byteOffset + byteLength) value is out of bounds");
  }

  this._offset = 0;

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

  if (this._isDataView) { // DataView: we use the direct method
    for (var type in dataTypes) {
      if (!dataTypes.hasOwnProperty(type)) {
        continue;
      }
      (function(type, view){
        var size = dataTypes[type];
        view['get' + type] = function (byteOffset, littleEndian) {
          // Handle the lack of endianness
          if (littleEndian === undefined) {
            littleEndian = view._littleEndian;
          }

          // Handle the lack of byteOffset
          if (byteOffset === undefined) {
            byteOffset = view._offset;
          }

          // Move the internal offset forward
          view._offset = byteOffset + size;

          return view._view['get' + type](byteOffset, littleEndian);
        }
      })(type, this);
    }
  } else if (this._isNodeBuffer && compatibility.NodeBuffer) {
    for (var type in dataTypes) {
      if (!dataTypes.hasOwnProperty(type)) {
        continue;
      }

      var name;
      if (type === 'Int8' || type === 'Uint8') {
        name = 'read' + nodeNaming[type];
      } else if (littleEndian) {
        name = 'read' + nodeNaming[type] + 'LE';
      } else {
        name = 'read' + nodeNaming[type] + 'BE';
      }

      (function(type, view, name){
        var size = dataTypes[type];
        view['get' + type] = function (byteOffset, littleEndian) {
          // Handle the lack of endianness
          if (littleEndian === undefined) {
            littleEndian = view._littleEndian;
          }

          // Handle the lack of byteOffset
          if (byteOffset === undefined) {
            byteOffset = view._offset;
          }

          // Move the internal offset forward
          view._offset = byteOffset + size;

          return view.buffer[name](view._start + byteOffset);
        }
      })(type, this, name);
    }
  } else {
    for (var type in dataTypes) {
      if (!dataTypes.hasOwnProperty(type)) {
        continue;
      }
      (function(type, view){
        var size = dataTypes[type];
        view['get' + type] = function (byteOffset, littleEndian) {
          // Handle the lack of endianness
          if (littleEndian === undefined) {
            littleEndian = view._littleEndian;
          }

          // Handle the lack of byteOffset
          if (byteOffset === undefined) {
            byteOffset = view._offset;
          }

          // Move the internal offset forward
          view._offset = byteOffset + size;

          if (view._isArrayBuffer && (view._start + byteOffset) % size === 0 && (size === 1 || littleEndian)) {
            // ArrayBuffer: we use a typed array of size 1 if the alignment is good
            // ArrayBuffer does not support endianess flag (for size > 1)
            return new global[type + 'Array'](view.buffer, view._start + byteOffset, 1)[0];
          } else {
            // Error checking:
            if (typeof byteOffset !== 'number') {
              throw new TypeError('jDataView byteOffset is not a number');
            }
            if (byteOffset + size > view.byteLength) {
              throw new Error('jDataView (byteOffset + size) value is out of bounds');
            }

            return view['_get' + type](view._start + byteOffset, littleEndian);
          }
        }
      })(type, this);
    }
  }
};

if (compatibility.NodeBuffer) {
  jDataView.createBuffer = function () {
    var buffer = new Buffer(arguments.length);
    for (var i = 0; i < arguments.length; ++i) {
      buffer[i] = arguments[i];
    }
    return buffer;
  }
} else if (compatibility.ArrayBuffer) {
  jDataView.createBuffer = function () {
    var buffer = new ArrayBuffer(arguments.length);
    var view = new Int8Array(buffer);
    for (var i = 0; i < arguments.length; ++i) {
      view[i] = arguments[i];
    }
    return buffer;
  }
} else {
  jDataView.createBuffer = function () {
    return String.fromCharCode.apply(null, arguments);
  }
}

jDataView.prototype = {
  compatibility: compatibility,

  // Helpers

  getString: function (length, byteOffset) {
    var value;

    // Handle the lack of byteOffset
    if (byteOffset === undefined) {
      byteOffset = this._offset;
    }

    // Error Checking
    if (typeof byteOffset !== 'number') {
      throw new TypeError('jDataView byteOffset is not a number');
    }
    if (length < 0 || byteOffset + length > this.byteLength) {
      throw new Error('jDataView length or (byteOffset+length) value is out of bounds');
    }

    if (this._isNodeBuffer) {
      value = this.buffer.toString('ascii', this._start + byteOffset, this._start + byteOffset + length);
    }
    else {
      value = '';
      for (var i = 0; i < length; ++i) {
        var char = this.getUint8(byteOffset + i);
        value += String.fromCharCode(char > 127 ? 65533 : char);
      }
    }

    this._offset = byteOffset + length;
    return value;
  },

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

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

  seek: function (byteOffset) {
    if (typeof byteOffset !== 'number') {
      throw new TypeError('jDataView byteOffset is not a number');
    }
    if (byteOffset < 0 || byteOffset > this.byteLength) {
      throw new Error('jDataView byteOffset value is out of bounds');
    }

    return this._offset = byteOffset;
  },

  // Compatibility functions on a String Buffer

  _endianness: function (byteOffset, pos, max, littleEndian) {
    return byteOffset + (littleEndian ? max - pos - 1 : pos);
  },

  _getFloat64: function (byteOffset, littleEndian) {
    var b0 = this._getUint8(this._endianness(byteOffset, 0, 8, littleEndian)),
      b1 = this._getUint8(this._endianness(byteOffset, 1, 8, littleEndian)),
      b2 = this._getUint8(this._endianness(byteOffset, 2, 8, littleEndian)),
      b3 = this._getUint8(this._endianness(byteOffset, 3, 8, littleEndian)),
      b4 = this._getUint8(this._endianness(byteOffset, 4, 8, littleEndian)),
      b5 = this._getUint8(this._endianness(byteOffset, 5, 8, littleEndian)),
      b6 = this._getUint8(this._endianness(byteOffset, 6, 8, littleEndian)),
      b7 = this._getUint8(this._endianness(byteOffset, 7, 8, littleEndian)),

      sign = 1 - (2 * (b0 >> 7)),
      exponent = ((((b0 << 1) & 0xff) << 3) | (b1 >> 4)) - (Math.pow(2, 10) - 1),

    // Binary operators such as | and << operate on 32 bit values, using + and Math.pow(2) instead
      mantissa = ((b1 & 0x0f) * Math.pow(2, 48)) + (b2 * Math.pow(2, 40)) + (b3 * Math.pow(2, 32)) +
            (b4 * Math.pow(2, 24)) + (b5 * Math.pow(2, 16)) + (b6 * Math.pow(2, 8)) + b7;

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

    if (exponent === -1023) { // Denormalized
      return sign * mantissa * Math.pow(2, -1022 - 52);
    }

    return sign * (1 + mantissa * Math.pow(2, -52)) * Math.pow(2, exponent);
  },

  _getFloat32: function (byteOffset, littleEndian) {
    var b0 = this._getUint8(this._endianness(byteOffset, 0, 4, littleEndian)),
      b1 = this._getUint8(this._endianness(byteOffset, 1, 4, littleEndian)),
      b2 = this._getUint8(this._endianness(byteOffset, 2, 4, littleEndian)),
      b3 = this._getUint8(this._endianness(byteOffset, 3, 4, littleEndian)),

      sign = 1 - (2 * (b0 >> 7)),
      exponent = (((b0 << 1) & 0xff) | (b1 >> 7)) - 127,
      mantissa = ((b1 & 0x7f) << 16) | (b2 << 8) | b3;

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

    if (exponent === -127) { // Denormalized
      return sign * mantissa * Math.pow(2, -126 - 23);
    }

    return sign * (1 + mantissa * Math.pow(2, -23)) * Math.pow(2, exponent);
  },

  _getInt32: function (byteOffset, littleEndian) {
    var b = this._getUint32(byteOffset, littleEndian);
    return b > Math.pow(2, 31) - 1 ? b - Math.pow(2, 32) : b;
  },

  _getUint32: function (byteOffset, littleEndian) {
    var b3 = this._getUint8(this._endianness(byteOffset, 0, 4, littleEndian)),
      b2 = this._getUint8(this._endianness(byteOffset, 1, 4, littleEndian)),
      b1 = this._getUint8(this._endianness(byteOffset, 2, 4, littleEndian)),
      b0 = this._getUint8(this._endianness(byteOffset, 3, 4, littleEndian));

    return (b3 * Math.pow(2, 24)) + (b2 << 16) + (b1 << 8) + b0;
  },

  _getInt16: function (byteOffset, littleEndian) {
    var b = this._getUint16(byteOffset, littleEndian);
    return b > Math.pow(2, 15) - 1 ? b - Math.pow(2, 16) : b;
  },

  _getUint16: function (byteOffset, littleEndian) {
    var b1 = this._getUint8(this._endianness(byteOffset, 0, 2, littleEndian)),
      b0 = this._getUint8(this._endianness(byteOffset, 1, 2, littleEndian));

    return (b1 << 8) + b0;
  },

  _getInt8: function (byteOffset) {
    var b = this._getUint8(byteOffset);
    return b > Math.pow(2, 7) - 1 ? b - Math.pow(2, 8) : b;
  },

  _getUint8: function (byteOffset) {
    if (this._isArrayBuffer) {
      return new Uint8Array(this.buffer, byteOffset, 1)[0];
    }
    else if (this._isNodeBuffer) {
      return this.buffer[byteOffset];
    } else {
      return this.buffer.charCodeAt(byteOffset) & 0xff;
    }
  }
};

if (typeof jQuery !== 'undefined' && jQuery.fn.jquery >= "1.6.2") {
  var convertResponseBodyToText = function (byteArray) {
    // http://jsperf.com/vbscript-binary-download/6
    var scrambledStr;
    try {
      scrambledStr = IEBinaryToArray_ByteStr(byteArray);
    } catch (e) {
      // http://stackoverflow.com/questions/1919972/how-do-i-access-xhr-responsebody-for-binary-data-from-javascript-in-ie
      // http://miskun.com/javascript/internet-explorer-and-binary-files-data-access/
      var IEBinaryToArray_ByteStr_Script =
        "Function IEBinaryToArray_ByteStr(Binary)\r\n"+
        " IEBinaryToArray_ByteStr = CStr(Binary)\r\n"+
        "End Function\r\n"+
        "Function IEBinaryToArray_ByteStr_Last(Binary)\r\n"+
        " Dim lastIndex\r\n"+
        " lastIndex = LenB(Binary)\r\n"+
        " if lastIndex mod 2 Then\r\n"+
        "   IEBinaryToArray_ByteStr_Last = AscB( MidB( Binary, lastIndex, 1 ) )\r\n"+
        " Else\r\n"+
        "   IEBinaryToArray_ByteStr_Last = -1\r\n"+
        " End If\r\n"+
        "End Function\r\n";

      // http://msdn.microsoft.com/en-us/library/ms536420(v=vs.85).aspx
      // proprietary IE function
      window.execScript(IEBinaryToArray_ByteStr_Script, 'vbscript');

      scrambledStr = IEBinaryToArray_ByteStr(byteArray);
    }

    var lastChr = IEBinaryToArray_ByteStr_Last(byteArray),
    result = "",
    i = 0,
    l = scrambledStr.length % 8,
    thischar;
    while (i < l) {
      thischar = scrambledStr.charCodeAt(i++);
      result += String.fromCharCode(thischar & 0xff, thischar >> 8);
    }
    l = scrambledStr.length
    while (i < l) {
      result += String.fromCharCode(
        (thischar = scrambledStr.charCodeAt(i++), thischar & 0xff), thischar >> 8,
        (thischar = scrambledStr.charCodeAt(i++), thischar & 0xff), thischar >> 8,
        (thischar = scrambledStr.charCodeAt(i++), thischar & 0xff), thischar >> 8,
        (thischar = scrambledStr.charCodeAt(i++), thischar & 0xff), thischar >> 8,
        (thischar = scrambledStr.charCodeAt(i++), thischar & 0xff), thischar >> 8,
        (thischar = scrambledStr.charCodeAt(i++), thischar & 0xff), thischar >> 8,
        (thischar = scrambledStr.charCodeAt(i++), thischar & 0xff), thischar >> 8,
        (thischar = scrambledStr.charCodeAt(i++), thischar & 0xff), thischar >> 8);
    }
    if (lastChr > -1) {
      result += String.fromCharCode(lastChr);
    }
    return result;
  };

  jQuery.ajaxSetup({
    converters: {
      '* dataview': function(data) {
        return new jDataView(data);
      }
    },
    accepts: {
      dataview: "text/plain; charset=x-user-defined"
    },
    responseHandler: {
      dataview: function (responses, options, xhr) {
        // Array Buffer Firefox
        if ('mozResponseArrayBuffer' in xhr) {
          responses.text = xhr.mozResponseArrayBuffer;
        }
        // Array Buffer Chrome
        else if ('responseType' in xhr && xhr.responseType === 'arraybuffer' && xhr.response) {
          responses.text = xhr.response;
        }
        // Internet Explorer (Byte array accessible through VBScript -- convert to text)
        else if ('responseBody' in xhr) {
          responses.text = convertResponseBodyToText(xhr.responseBody);
        }
        // Older Browsers
        else {
          responses.text = xhr.responseText;
        }
      }
    }
  });

  jQuery.ajaxPrefilter('dataview', function(options, originalOptions, jqXHR) {
    // trying to set the responseType on IE 6 causes an error
    if (jQuery.support.ajaxResponseType) {
      if (!options.hasOwnProperty('xhrFields')) {
        options.xhrFields = {};
      }
      options.xhrFields.responseType = 'arraybuffer';
    }
    options.mimeType = 'text/plain; charset=x-user-defined';
  });
}

global.jDataView = (global.module || {}).exports = jDataView;
if (typeof module !== 'undefined') {
  module.exports = jDataView;
}

})(this);