rochars / byte-data

import endianness from 'endianness';

import { pack as packUTF8, unpack as unpackUTF8 } from 'utf8-buffer';

import { IntParser } from './lib/int-parser';

import { IEEE754Buffer } from 'ieee754-buffer';

/**

 * Read a string of UTF-8 characters from a byte buffer.

 * @param {!Uint8Array|!Array<number>} buffer A byte buffer.

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

 * @param {number=} end The buffer index to stop reading, non inclusive.

 *   Assumes buffer length if undefined.

 * @return {string}

 */

export function unpackString(buffer, index=0, end=buffer.length) {

  return unpackUTF8(buffer, index, end);

}

/**

 * Write a string of UTF-8 characters as a byte buffer.

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

 * @return {!Array<number>} The UTF-8 string bytes.

 */ 

export function packString(str) {

  /** @type {!Array<number>} */

  let buffer = [];

  packUTF8(str, buffer, 0);

  return buffer;

}

/**

 * Write a string of UTF-8 characters to a byte buffer.

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

 * @param {!Uint8Array|!Array<number>} buffer The output buffer.

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

 *   Assumes zero if undefined.

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

 */

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

  return packUTF8(str, buffer, index);

}

// Numbers

/**

 * Pack a array of numbers to a byte buffer.

 * All other packing functions are interfaces to this function.

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

 * @param { {bits:number, fp: boolean, signed: boolean, be: boolean} } theType

    The type definition.

 * @param {!Uint8Array|!Array<number>} buffer The output buffer.

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

 *   Assumes zero if undefined.

 * @param {boolean=} clamp True to clamp ints on overflow. Default is false.

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

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

 * @throws {RangeError} On overflow.

 * @throws {TypeError} If input is not valid.

 */

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

  theType = theType || {};

  /** @type {Object} */

  let packer = getParser_(theType.bits, theType.fp, theType.signed, clamp);

  /** @type {number} */

  let offset = Math.ceil(theType.bits / 8);

  /** @type {number} */

  let i = 0;

  /** @type {number} */

  let start = index;

  try {

    for (let valuesLen = values.length; i < valuesLen; i++) {

      index = packer.pack(buffer, values[i], index);

    }

    if (theType.be) {

      endianness(buffer, offset, start, index);

    }

  } catch (e) {

    throwValueError_(e, values[i], i);

  }

  return index;

}

/**

 * Unpack a array of numbers to a typed array.

 * All other unpacking functions are interfaces to this function.

 * @param {!Uint8Array|!Array<number>} buffer The byte buffer.

 * @param { {bits:number, fp: boolean, signed: boolean, be: boolean} } theType

    The type definition.

 * @param {!TypedArray|!Array<number>} output The output array.

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

 *   Assumes zero if undefined.

 * @param {number=} end The buffer index to stop reading.

 *   Assumes the buffer length if undefined.

 * @param {boolean=} safe If set to false, extra bytes in the end of

 *   the array are ignored and input buffers with insufficient bytes will

 *   write nothing to the output array. If safe is set to true the function

 *   will throw a 'Bad buffer length' error. Defaults to false.

 * @param {boolean=} clamp True to clamp ints on overflow. Default is false.

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

 * @throws {RangeError} On overflow

 */

export function unpackArrayTo(

    buffer, theType, output, start=0, end=buffer.length,

    safe=false, clamp=false) {

  theType = theType || {};

  /** @type {Object} */

  let packer = getParser_(theType.bits, theType.fp, theType.signed, clamp);

  /** @type {number} */

  let offset = Math.ceil(theType.bits / 8);

  // getUnpackLen_ will either fix the length of the input buffer

  // according to the byte offset of the type (on unsafe mode) or

  // throw a Error if the input buffer has a bad length (on safe mode)

  end = getUnpackLen_(buffer, start, end, offset, safe);

  /** @type {number} */

  let index = 0;

  let j = start;

  try {

    if (theType.be) {

      endianness(buffer, offset, start, end);

    }

    for (; j < end; j += offset, index++) {

      output[index] = packer.unpack(buffer, j);

    }

    if (theType.be) {

      endianness(buffer, offset, start, end);

    }

  } catch (e) {

    throwValueError_(e, buffer.slice(j, j + offset), j);

  }

}

/**

 * Pack a number to a byte buffer.

 * @param {number} value The value.

 * @param { {bits:number, fp: boolean, signed: boolean, be: boolean} } theType

    The type definition.

 * @param {!Uint8Array|!Array<number>} buffer The output buffer.

 * @param {number=} index The buffer index to write. Assumes 0 if undefined.

 * @param {boolean=} clamp True to clamp ints on overflow. Default is false.

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

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

 * @throws {RangeError} On overflow.

 * @throws {TypeError} If input is not valid.

 */

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

  return packArrayTo([value], theType, buffer, index, clamp);

}

/**

 * Pack a number as a byte buffer.

 * @param {number} value The number.

 * @param {!{bits:number, fp: boolean, signed: boolean, be: boolean}} theType

    The type definition.

 * @param {boolean=} clamp True to clamp ints on overflow. Default is false.

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

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

 * @throws {RangeError} On overflow.

 * @throws {TypeError} If input is not valid.

 */

export function pack(value, theType, clamp=false) {

  /** @type {!Array<number>} */

  let output = [];

  packTo(value, theType, output, 0, clamp);

  return output;

}

/**

 * Pack an array of numbers as a byte buffer.

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

 * @param {!{bits:number, fp: boolean, signed: boolean, be: boolean}} theType

    The type definition.

 * @param {boolean=} clamp True to clamp ints on overflow. Default is false.

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

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

 * @throws {RangeError} On overflow.

 * @throws {TypeError} If input is not valid.

 */

export function packArray(values, theType, clamp=false) {

  /** @type {!Array<number>} */

  let output = [];

  packArrayTo(values, theType, output, 0, clamp);

  return output;

}

/**

 * Unpack an array of numbers from a byte buffer.

 * @param {!Uint8Array|!Array<number>} buffer The byte buffer.

 * @param {!{bits:number, fp: boolean, signed: boolean, be: boolean}} theType

    The type definition.

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

 *   Assumes zero if undefined.

 * @param {number=} end The buffer index to stop reading.

 *   Assumes the buffer length if undefined.

 * @param {boolean=} safe If set to false, extra bytes in the end of

 *   the array are ignored and input buffers with insufficient bytes will

 *   output a empty array. If safe is set to true the function

 *   will throw a 'Bad buffer length' error. Defaults to false.

 * @param {boolean=} clamp True to clamp ints on overflow. Default is false.

 * @return {!Array<number>}

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

 * @throws {RangeError} On overflow

 */

export function unpackArray(

    buffer, theType, start=0, end=buffer.length, safe=false, clamp=false) {

  /** @type {!Array<number>} */

  let output = [];

  unpackArrayTo(buffer, theType, output, start, end, safe, clamp);

  return output;

}

/**

 * Unpack a number from a byte buffer.

 * @param {!Uint8Array|!Array<number>} buffer The byte buffer.

 * @param {!{bits:number, fp: boolean, signed: boolean, be: boolean}} theType

    The type definition.

 * @param {number=} index The buffer index to read. Assumes zero if undefined.

 * @param {boolean=} clamp True to clamp ints on overflow. Default is false.

 * @return {number}

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

 * @throws {Error} On bad buffer length.

 * @throws {RangeError} On overflow

 */

export function unpack(buffer, theType, index=0, clamp=false) {

  return unpackArray(

    buffer, theType, index, index + Math.ceil(theType.bits / 8),

    true, clamp)[0];

}

/**

 * Throw a error with information about the problem.

 * @param {!Object} err The Error object that is being raised.

 * @param {*} value The value that caused the error.

 * @param {number} index The index of the value that caused the error.

 * @throws {RangeError|TypeError|Error} A Error with a message.

 * @private

 */

function throwValueError_(err, value, index) {

  err.message = err.constructor.name +

    ' at index ' + index + ': ' + value;

  throw err;

}

/**

 * Unpack a array of numbers to a typed array.

 * All other unpacking functions are interfaces to this function.

 * @param {!Uint8Array|!Array<number>} buffer The byte buffer.

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

 * @param {number=} end The buffer index to stop reading.

 * @param {number=} offset The number of bytes used by the type.

 * @param {boolean=} safe True for size-safe buffer reading.

 * @throws {Error} On bad buffer length, if safe.

 * @private

 */

function getUnpackLen_(buffer, start, end, offset, safe) {

  /** @type {number} */

  let extra = (end - start) % offset;

  if (safe && (extra || buffer.length < offset)) {

    throw new Error('Bad buffer length');

  }

  return end - extra;

}

/**

 * Return a parser for int, uint or fp numbers.

 * @param {number} bits The number of bits.

 * @param {boolean} fp True for fp numbers, false otherwise.

 * @param {boolean} signed True for signed ints, false otherwise.

 * @param {boolean} clamp True to clamp ints on overflow, false otherwise.

 * @return {!Object}

 * @private

 */

function getParser_(bits, fp, signed, clamp) {

  if (fp) {

    validateFloatType(bits);

  } else {

    validateIntType(bits);

  }

  if (fp && bits === 16) {

    return new IEEE754Buffer(5, 11);

  } else if (fp && bits == 32) {

    return new IEEE754Buffer(8, 23);

  } else if(fp && bits == 64) {

    return new IEEE754Buffer(11, 52);

  }

  return new IntParser(bits, signed, clamp);

}

/**

 * The type definition error message.

 * @type {string}

 * @private

 */

const TYPE_ERR = 'Unsupported type';

/**

 * Validate the type definition of floating-point numbers.

 * @param {number} bits The number of bits.

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

 * @private

 */

function validateFloatType(bits) {

  if (!bits || bits !== 16 && bits !== 32 && bits !== 64) {

    throw new Error(TYPE_ERR + ': float, bits: ' + bits);

  }

}

/**

 * Validate the type definition of integers.

 * @param {number} bits The number of bits.

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

 * @private

 */

function validateIntType(bits) {

  if (!bits || bits < 1 || bits > 53) {

    throw new Error(TYPE_ERR + ': int, bits: ' + bits);

  }

}