rochars / byte-data

main.js

/*
 * byte-data: Pack and unpack binary data.
 * https://github.com/rochars/byte-data
 *
 * Copyright (c) 2017-2018 Rafael da Silva Rocha.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */

/**
 * @fileoverview The byte-data API.
 */

/** @module byteData */

/**
 * byte-data standard types.
 * @type {!Object}
 */
export {types} from './lib/types.js';

/**
 * @constructor
 */
import Integer from './lib/integer';

/**
 * @type {!Function}
 * @private
 */
import {endianness} from 'endianness';
/**
 * @type {!Int8Array}
 * @private
 */
const int8_ = new Int8Array(8);
/**
 * @type {!Uint32Array}
 * @private
 */
const ui32_ = new Uint32Array(int8_.buffer);
/**
 * @type {!Float32Array}
 * @private
 */
const f32_ = new Float32Array(int8_.buffer);
/**
 * @type {!Float64Array}
 * @private
 */
const f64_ = new Float64Array(int8_.buffer);
/**
 * @type {Function}
 * @private
 */
let reader_;
/**
 * @type {Function}
 * @private
 */
let writer_;
/**
 * @type {Object}
 * @private
 */
let gInt_ = {};

/**
 * Pack a number or a string as a byte buffer.
 * @param {number|string} value The value.
 * @param {!Object} theType The type definition.
 * @return {!Array<number>}
 * @throws {Error} If the type definition is not valid.
 * @throws {Error} If the value is not valid.
 */
export function pack(value, theType) {
  setUp_(theType);
  return toBytes_([value], theType);
}

/**
 * Pack an array of numbers or strings to a byte buffer.
 * @param {!Array<number|string>} values The values.
 * @param {!Object} theType The type definition.
 * @return {!Array<number>}
 * @throws {Error} If the type definition is not valid.
 * @throws {Error} If any of the values are not valid.
 */
export function packArray(values, theType) {
  setUp_(theType);
  return toBytes_(values, theType);
}

/**
 * Pack a number or a string as a byte buffer.
 * @param {number|string} value The value.
 * @param {!Object} theType The type definition.
 * @param {!Uint8Array|!Array<number>} buffer The output buffer.
 * @param {number} index The buffer index to write.
 * @return {number} The next index to start writing.
 * @throws {Error} If the type definition is not valid.
 * @throws {Error} If the value is not valid.
 */
export function packTo(value, theType, buffer, index) {
  setUp_(theType);
  let validate = validateNotNull_;
  if (theType['char']) {
    validate = validateString_;
  }
  return writeBytes_(value,
    theType,
    buffer,
    index,
    index + theType['offset'],
    validate,
    theType['be']);
}

/**
 * Pack a number or a string as a byte buffer.
 * @param {number|string} values The value.
 * @param {!Object} theType The type definition.
 * @param {!Uint8Array|!Array<number>} buffer The output buffer.
 * @param {number} index The buffer index to write.
 * @return {number} The next index to start writing.
 * @throws {Error} If the type definition is not valid.
 * @throws {Error} If the value is not valid.
 */
export function packArrayTo(values, theType, buffer, index) {
  setUp_(theType);
  let validate = validateNotNull_;
  if (theType['char']) {
    validate = validateString_;
  }
  let be = theType['be'];
  let offset = theType['offset'];
  for (let i=0; i<values.length; i++) {
    index = writeBytes_(
      values[i],
      theType,
      buffer,
      index,
      index + offset,
      validate, be);
  }
  return index;
}

/**
 * Unpack a number or a string from a byte buffer.
 * @param {!Array<number>|!Uint8Array} buffer The byte buffer.
 * @param {!Object} theType The type definition.
 * @return {number|string}
 * @throws {Error} If the type definition is not valid
 */
export function unpack(buffer, theType) {
  setUp_(theType);
  let values = fromBytes_(
    buffer.slice(0, theType['offset']), theType);
  return values[0];
}

/**
 * Unpack an array of numbers or strings from a byte buffer.
 * @param {!Array<number>|!Uint8Array} buffer The byte buffer.
 * @param {!Object} theType The type definition.
 * @return {!Array<number|string>}
 * @throws {Error} If the type definition is not valid.
 */
export function unpackArray(buffer, theType) {
  setUp_(theType);
  return fromBytes_(buffer, theType);
}

/**
 * Unpack a number or a string from a byte buffer.
 * @param {!Array<number>|!Uint8Array} buffer The byte buffer.
 * @param {!Object} theType The type definition.
 * @param {number=} index The buffer index to read.
 * @return {number|string}
 * @throws {Error} If the type definition is not valid
 */
export function unpackFrom(buffer, theType, index=0) {
  setUp_(theType);
  return readBytes_(buffer, theType, index);
}

/**
 * Unpack a number or a string from a byte buffer.
 * @param {!Array<number>|!Uint8Array} buffer The byte buffer.
 * @param {!Object} theType The type definition.
 * @param {number=} start The start index. Assumes 0.
 * @param {?number=} end The end index. Assumes the array length.
 * @return {!Array<number>}
 * @throws {Error} If the type definition is not valid
 */
export function unpackArrayFrom(buffer, theType, start=0, end=null) {
  setUp_(theType);
  if (theType['be']) {
    endianness(buffer, theType['offset']);
  }
  let len = end || buffer.length;
  let values = [];
  for (let i=start; i<len; i+=theType['offset']) {
    values.push(reader_(buffer, i));
  }
  if (theType['be']) {
    endianness(buffer, theType['offset']);
  }
  return values;
}

/**
 * Turn a byte buffer into what the bytes represent.
 * @param {!Array<number|string>|!Uint8Array} buffer An array of bytes.
 * @param {!Object} theType The type definition.
 * @return {number}
 * @private
 */
function readBytes_(buffer, theType, start) {
  if (theType['be']) {
    endianness(buffer, theType['offset'], start, start + theType['offset']);
  }
  let value = reader_(buffer, start);
  if (theType['be']) {
    endianness(buffer, theType['offset'], start, start + theType['offset']);
  }
  return value;
}

/**
 * Turn a byte buffer into what the bytes represent.
 * @param {!Array<number|string>|!Uint8Array} buffer An array of bytes.
 * @param {!Object} theType The type definition.
 * @return {!Array<number>}
 * @private
 */
function fromBytes_(buffer, theType) {
  if (theType['be']) {
    endianness(buffer, theType['offset']);
  }
  let len = buffer.length;
  let values = [];
  len = len - (theType['offset'] - 1);
  for (let i=0; i<len; i+=theType['offset']) {
    values.push(reader_(buffer, i));
  }
  return values;
}

/**
 * Turn numbers and strings to bytes.
 * @param {!Array<number|string>} values The data.
 * @param {!Object} theType The type definition.
 * @return {!Array<number|string>} the data as a byte buffer.
 * @private
 */
function toBytes_(values, theType) {
  let j = 0;
  let bytes = [];
  let len = values.length;
  let validate = validateNotNull_;
  if (theType['char']) {
    validate = validateString_;
  }
  for(let i=0; i < len; i++) {
    validate(values[i], theType);
    j = writer_(bytes, values[i], j);
  }
  if (theType['be']) {
    endianness(bytes, theType['offset']);
  }
  return bytes;
}

/**
 * Turn numbers and strings to bytes.
 * @param {number|string} value The value to be packed.
 * @param {!Object} theType The type definition.
 * @param {!Object} buffer The buffer to write the bytes to.
 * @param {number} index The index to start writing.
 * @param {number} len The end index.
 * @param {!Function} validate The function used to validate input.
 * @param {boolean} be True if big-endian.
 * @return {number} the new index to be written.
 * @private
 */
function writeBytes_(value, theType, buffer, index, len, validate, be) {
  for(let i=index; i<len; i++) {
    validate(value, theType);
    i = writer_(buffer, value, i);

You seem to be assigning a new value to the loop variable i here. Please check if this was indeed your intention. Even if it was, consider using another kind of loop instead.

    index = i;
  }
  if (be) {
    endianness(
      buffer, theType['offset'], index - theType['offset'], index);
  }
  return index;
}

/**
 * Read int values from bytes.
 * @param {!Array<number>|!Uint8Array} bytes An array of bytes.
 * @param {number} i The index to read.
 * @return {number}
 * @private
 */
function readInt_(bytes, i) {
  return gInt_.read(bytes, i);
}

/**
 * Read 1 16-bit float from bytes.
 * Thanks https://stackoverflow.com/a/8796597
 * @param {!Array<number>|!Uint8Array} bytes An array of bytes.
 * @param {number} i The index to read.
 * @return {number}
 * @private
 */
function read16F_(bytes, i) {
  let int = gInt_.read(bytes, i);
  let exponent = (int & 0x7C00) >> 10;
  let fraction = int & 0x03FF;
  let floatValue;
  if (exponent) {
    floatValue =  Math.pow(2, exponent - 15) * (1 + fraction / 0x400);
  } else {
    floatValue = 6.103515625e-5 * (fraction / 0x400);
  }
  return floatValue * (int >> 15 ? -1 : 1);
}

/**
 * Read 1 32-bit float from bytes.
 * @param {!Array<number>|!Uint8Array} bytes An array of bytes.
 * @param {number} i The index to read.
 * @return {number}
 * @private
 */
function read32F_(bytes, i) {
  ui32_[0] = gInt_.read(bytes, i);
  return f32_[0];
}

/**
 * Read 1 64-bit float from bytes.
 * Thanks https://gist.github.com/kg/2192799
 * @param {!Array<number>|!Uint8Array} bytes An array of bytes.
 * @param {number} i The index to read.
 * @return {number}
 * @private
 */
function read64F_(bytes, i) {
  ui32_[0] = gInt_.read(bytes, i);
  ui32_[1] = gInt_.read(bytes, i + 4);
  return f64_[0];
}

/**
 * Read 1 char from bytes.
 * @param {!Array<number>|!Uint8Array} bytes An array of bytes.
 * @param {number} i The index to read.
 * @return {string}
 * @private
 */
function readChar_(bytes, i) {
  let chrs = '';
  for(let j=0; j < gInt_.offset; j++) {
    chrs += String.fromCharCode(bytes[i+j]);
  }
  return chrs;
}

/**
 * Write a integer value to a byte buffer.
 * @param {!Array<number>|!Uint8Array} bytes An array of bytes.
 * @param {number} number The number to write as bytes.
 * @param {number} j The index being written in the byte buffer.
 * @return {!number} The next index to write on the byte buffer.
 * @private
 */
function writeInt_(bytes, number, j) {
  return gInt_.write(bytes, number, j);
}

/**
 * Write one 16-bit float as a binary value.
 * @param {!Array<number>|!Uint8Array} bytes An array of bytes.
 * @param {number} number The number to write as bytes.
 * @param {number} j The index being written in the byte buffer.
 * @return {number} The next index to write on the byte buffer.
 * @private
 */
function write16F_(bytes, number, j) {
  f32_[0] = number;
  let x = ui32_[0];
  let bits = (x >> 16) & 0x8000;
  let m = (x >> 12) & 0x07ff;
  let e = (x >> 23) & 0xff;
  if (e >= 103) {
    bits |= ((e - 112) << 10) | (m >> 1);
    bits += m & 1;
  }
  bytes[j++] = bits & 0xFF;
  bytes[j++] = bits >>> 8 & 0xFF;
  return j;
}

/**
 * Write one 32-bit float as a binary value.
 * @param {!Array<number>|!Uint8Array} bytes An array of bytes.
 * @param {number} number The number to write as bytes.
 * @param {number} j The index being written in the byte buffer.
 * @return {number} The next index to write on the byte buffer.
 * @private
 */
function write32F_(bytes, number, j) {
  f32_[0] = number;
  return gInt_.write(bytes, ui32_[0], j);
}

/**
 * Write one 64-bit float as a binary value.
 * @param {!Array<number>|!Uint8Array} bytes An array of bytes.
 * @param {number} number The number to write as bytes.
 * @param {number} j The index being written in the byte buffer.
 * @return {number} The next index to write on the byte buffer.
 * @private
 */
function write64F_(bytes, number, j) {
  f64_[0] = number;
  j = gInt_.write(bytes, ui32_[0], j);
  return gInt_.write(bytes, ui32_[1], j);
}

/**
 * Write one char as a byte.
 * @param {!Array<number>|!Uint8Array} bytes An array of bytes.
 * @param {string} str The string to write as bytes.
 * @param {number} j The index being written in the byte buffer.
 * @return {number} The next index to write on the byte buffer.
 * @private
 */
function writeChar_(bytes, str, j) {
  for (let i=0; i<str.length; i++) {
    bytes[j++] = str.charCodeAt(i);
  }
  return j;
}

/**
 * Set the function to unpack the data.
 * @param {!Object} theType The type definition.
 * @private
 */
function setReader(theType) {
  if (theType['float']) {
    if (theType['bits'] == 16) {
      reader_ = read16F_;
    } else if(theType['bits'] == 32) {
      reader_ = read32F_;
    } else if(theType['bits'] == 64) {
      reader_ = read64F_;
    }
  } else if (theType['char']) {
    reader_ = readChar_;
  } else {
    reader_ = readInt_;
  }
}

/**
 * Set the function to pack the data.
 * @param {!Object} theType The type definition.
 * @private
 */
function setWriter(theType) {
  if (theType['float']) {
    if (theType['bits'] == 16) {
      writer_ = write16F_;
    } else if(theType['bits'] == 32) {
      writer_ = write32F_;
    } else if(theType['bits'] == 64) {
      writer_ = write64F_;
    }
  } else if (theType['char']) {
    writer_ = writeChar_;
  } else {
    writer_ = writeInt_;
  }   
}

/**
 * Validate the type and set up the packing/unpacking functions.
 * @param {!Object} theType The type definition.
 * @throws {Error} If the type definition is not valid.
 * @private
 */
function setUp_(theType) {
  validateType_(theType);
  theType['offset'] = theType['bits'] < 8 ? 1 : Math.ceil(theType['bits'] / 8);
  setReader(theType);
  setWriter(theType);
  if (!theType['char']) {
    gInt_ = new Integer(
      theType['bits'] == 64 ? 32 : theType['bits'],
      theType['float'] ? false : theType['signed']);
  } else {
    // Workaround; should not use Integer when type['char']
    gInt_.offset = theType['bits'] < 8 ? 1 : Math.ceil(theType['bits'] / 8);
  }
}

/**
 * Validate the type definition.
 * @param {!Object} theType The type definition.
 * @throws {Error} If the type definition is not valid.
 * @private
 */
function validateType_(theType) {
  if (!theType) {
    throw new Error('Undefined type.');
  }
  if (theType['float']) {
    validateFloatType_(theType);
  } else {
    if (theType['char']) {
      validateCharType_(theType);
    } else {
      validateIntType_(theType);
    }
  }
}

/**
 * Validate the type definition of floating point numbers.
 * @param {!Object} theType The type definition.
 * @throws {Error} If the type definition is not valid.
 * @private
 */
function validateFloatType_(theType) {
  if ([16,32,64].indexOf(theType['bits']) == -1) {
    throw new Error('Not a supported float type.');
  }
}

/**
 * Validate the type definition of char and strings.
 * @param {!Object} theType The type definition.
 * @throws {Error} If the type definition is not valid.
 * @private
 */
function validateCharType_(theType) {
  if (theType['bits'] < 8 || theType['bits'] % 2) {
    throw new Error('Wrong offset for type char.');
  }
}

/**
 * Validate the type definition of integers.
 * @param {!Object} theType The type definition.
 * @throws {Error} If the type definition is not valid.
 * @private
 */
function validateIntType_(theType) {
  if (theType['bits'] < 1 || theType['bits'] > 53) {
    throw new Error('Not a supported type.');
  }
}

/**
 * Validate strings with bad length.
 * @param {string|number} value The string to validate.
 * @param {!Object} theType The type definition.
 * @private
 */
function validateString_(value, theType) {
  validateNotNull_(value);
  if (value.length > theType['offset']) {
    throw new Error('String is bigger than its type definition.');
  } else if (value.length < theType['offset']) {
    throw new Error('String is smaller than its type definition.');
  }
}
/**
 * Validate that the value is not null.
 * @param {string|number} value The value.
 * @private
 */
function validateNotNull_(value) {
  if (value === null || value === undefined) {
    throw new Error('Cannot pack null or undefined values.');
  }
}