mathjs/lib/utils/bignumber/bitwise.js

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser with support for symbolic computation, comes with a large set of built-in functions and constants, and offers an integrated solution to work with dif

'use strict';

var bitNot = require('./bitNot');
/**
 * Applies bitwise function to numbers
 * @param {BigNumber} x
 * @param {BigNumber} y
 * @param {function (a, b)} func
 * @return {BigNumber}
 */


module.exports = function bitwise(x, y, func) {
  var BigNumber = x.constructor;
  var xBits, yBits;
  var xSign = +(x.s < 0);
  var ySign = +(y.s < 0);

  if (xSign) {
    xBits = decCoefficientToBinaryString(bitNot(x));

    for (var i = 0; i < xBits.length; ++i) {
      xBits[i] ^= 1;
    }
  } else {
    xBits = decCoefficientToBinaryString(x);
  }

  if (ySign) {
    yBits = decCoefficientToBinaryString(bitNot(y));

    for (var _i = 0; _i < yBits.length; ++_i) {
      yBits[_i] ^= 1;
    }
  } else {
    yBits = decCoefficientToBinaryString(y);
  }

  var minBits, maxBits, minSign;

  if (xBits.length <= yBits.length) {
    minBits = xBits;
    maxBits = yBits;
    minSign = xSign;
  } else {
    minBits = yBits;
    maxBits = xBits;
    minSign = ySign;
  }

  var shortLen = minBits.length;
  var longLen = maxBits.length;
  var expFuncVal = func(xSign, ySign) ^ 1;
  var outVal = new BigNumber(expFuncVal ^ 1);
  var twoPower = new BigNumber(1);
  var two = new BigNumber(2);
  var prevPrec = BigNumber.precision;
  BigNumber.config({
    precision: 1E9
  });

  while (shortLen > 0) {
    if (func(minBits[--shortLen], maxBits[--longLen]) === expFuncVal) {
      outVal = outVal.plus(twoPower);
    }

    twoPower = twoPower.times(two);
  }

  while (longLen > 0) {
    if (func(minSign, maxBits[--longLen]) === expFuncVal) {
      outVal = outVal.plus(twoPower);
    }

    twoPower = twoPower.times(two);
  }

  BigNumber.config({
    precision: prevPrec
  });

  if (expFuncVal === 0) {
    outVal.s = -outVal.s;
  }

  return outVal;
};
/* Extracted from decimal.js, and edited to specialize. */


function decCoefficientToBinaryString(x) {
  // Convert to string
  var a = x.d; // array with digits

  var r = a[0] + '';

  for (var i = 1; i < a.length; ++i) {
    var s = a[i] + '';

    for (var z = 7 - s.length; z--;) {
      s = '0' + s;
    }

    r += s;
  }

  var j = r.length;

  while (r.charAt(j) === '0') {
    j--;
  }

  var xe = x.e;
  var str = r.slice(0, j + 1 || 1);
  var strL = str.length;

  if (xe > 0) {
    if (++xe > strL) {
      // Append zeros.
      xe -= strL;

      while (xe--) {
        str += '0';
      }
    } else if (xe < strL) {
      str = str.slice(0, xe) + '.' + str.slice(xe);
    }
  } // Convert from base 10 (decimal) to base 2


  var arr = [0];

  for (var _i2 = 0; _i2 < str.length;) {
    var arrL = arr.length;

    while (arrL--) {
      arr[arrL] *= 10;
    }

    arr[0] += parseInt(str.charAt(_i2++)); // convert to int

    for (var _j = 0; _j < arr.length; ++_j) {
      if (arr[_j] > 1) {
        if (arr[_j + 1] === null || arr[_j + 1] === undefined) {
          arr[_j + 1] = 0;
        }

        arr[_j + 1] += arr[_j] >> 1;
        arr[_j] &= 1;
      }
    }
  }

  return arr.reverse();
}