rochars / byte-data

 * 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 */

import endianness from 'endianness';

import {validateType, validateNotUndefined} from './lib/validation.js';

// Strings

/**

 * Read a string from a byte buffer.

 * @param {!Uint8Array} bytes A byte buffer.

 * @param {number=} index The index to read.

 * @param {?number=} len The number of bytes to read.

 * @return {string}

 */

export function unpackString(bytes, index=0, len=null) {

  let chrs = '';

  len = len || bytes.length - index;

  for(let j = 0; j < len; j++) {

    chrs += String.fromCharCode(bytes[index+j]);

  }

  return chrs;

}

/**

 * Write a string as a byte buffer.

 * @param {string} str The string to pack.

 * @return {!Array<number>} The next index to write on the buffer.

 */

export function packString(str) {

  let bytes = [];

  for (let i = 0; i < str.length; i++) {

    bytes[i] = str.charCodeAt(i);

  }

  return bytes;

}

/**

 * Write a string to a byte buffer.

 * @param {string} str The string to pack.

 * @param {!Uint8Array} bytes A byte buffer.

 * @param {number=} index The index to write in the buffer.

 * @return {number} The next index to write in the buffer.

 */

export function packStringTo(str, bytes, index=0) {

  for (let i = 0; i < str.length; i++) {

    bytes[index] = str.charCodeAt(i);

    index++;

  }

  return index;

}

// Numbers

/**

 * Pack a number as a byte buffer.

 * @param {number} value The number.

 * @param {!Object} theType The type definition.

 * @return {!Array<number>} The packed value.

 * @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 as a byte buffer.

 * @param {!Array<number>} values The values.

 * @param {!Object} theType The type definition.

 * @return {!Array<number>} The packed values.

 * @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 to a byte buffer.

 * @param {number} value The value.

 * @param {!Object} theType The type definition.

 * @param {!Uint8Array} buffer The output buffer.

 * @param {number=} index The index to write.

 * @return {number} The next index to write.

 * @throws {Error} If the type definition is not valid.

 * @throws {Error} If the value is not valid.

 */

export function packTo(value, theType, buffer, index=0) {

  setUp_(theType);

  return writeBytes_(value,

    theType,

    buffer,

    index,

    index + theType['offset'],

    validateNotUndefined,

    theType['be']);

}

/**

 * Pack a array of numbers to a byte buffer.

 * @param {!Array<number>} values The value.

 * @param {!Object} theType The type definition.

 * @param {!Uint8Array} buffer The output buffer.

 * @param {number=} index The buffer index to write.

 * @return {number} The next index to write.

 * @throws {Error} If the type definition is not valid.

 * @throws {Error} If the value is not valid.

 */

export function packArrayTo(values, theType, buffer, index=0) {

  setUp_(theType);

  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,

      validateNotUndefined,

      be);

  }

  return index;

}

/**

 * Unpack a number from a byte buffer.

 * @param {!Uint8Array} buffer The byte buffer.

 * @param {!Object} theType The type definition.

 * @return {number}

 * @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 from a byte buffer.

 * @param {!Uint8Array} buffer The byte buffer.

 * @param {!Object} theType The type definition.

 * @return {!Array<number>}

 * @throws {Error} If the type definition is not valid.

 */

export function unpackArray(buffer, theType) {

  setUp_(theType);

  return fromBytes_(buffer, theType);

}

/**

 * Unpack a number from a byte buffer by index.

 * @param {!Uint8Array} buffer The byte buffer.

 * @param {!Object} theType The type definition.

 * @param {number=} index The buffer index to read.

 * @return {number}

 * @throws {Error} If the type definition is not valid

 */

export function unpackFrom(buffer, theType, index=0) {

  setUp_(theType);

  if (theType['be']) {

    endianness(buffer, theType['offset'], index, index + theType['offset']);

  }

  let value = reader_(buffer, index);

  if (theType['be']) {

    endianness(buffer, theType['offset'], index, index + theType['offset']);

  }

  return value;

}

/**

 * Unpack a array of numbers from a byte buffer by index.

 * @param {!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 buffer 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;

}

/**

 * @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_ = {};

/**

 * Turn numbers to bytes.

 * @param {number} value The value to be packed.

 * @param {!Object} theType The type definition.

 * @param {!Uint8Array} 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) {

  while (index < len) {

    validate(value, theType);

    index = writer_(buffer, value, index);

  }

  if (be) {

    endianness(

      buffer, theType['offset'], index - theType['offset'], index);

  }

  return index;

}

/**

 * Turn a byte buffer into what the bytes represent.

 * @param {!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 to bytes.

 * @param {!Array<number>} values The data.

 * @param {!Object} theType The type definition.

 * @return {!Array<number>} the data as a byte buffer.

 * @private

 */

function toBytes_(values, theType) {

  let j = 0;

  let bytes = [];

  let len = values.length;

  for(let i=0; i < len; i++) {

    validateNotUndefined(values[i]);

    j = writer_(bytes, values[i], j);

  }

  if (theType['be']) {

    endianness(bytes, theType['offset']);

  }

  return bytes;

}

/**

 * Read int values from bytes.

 * @param {!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 {!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 {!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 {!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];

}

/**

 * Write a integer value to a byte buffer.

 * @param {!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 {!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 {!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 {!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);

}

/**

 * 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 {

    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 {

    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);

  gInt_ = new Integer(

    theType['bits'] == 64 ? 32 : theType['bits'],

    theType['float'] ? false : theType['signed']);

}