diffusion/src/internal/util/math.js

Diffusion JavaScript client

"use strict";
/**
 * @module Util.Math
 *
 * @brief Mathenatical utility functions
 */
/* eslint-disable no-bitwise */
Object.defineProperty(exports, "__esModule", { value: true });
exports.MIN_SAFE_INTEGER = exports.MAX_SAFE_INTEGER = exports.MAX_INT32 = exports.findNextPowerOfTwo = exports.approximateSquareRoot = void 0;
var errors_1 = require("./../../errors/errors");
/**
 * Calculate the number of leading zeros in the binary representation of a number
 * using the minimal amount of bit-shifting
 *
 * @param  i the number to analyse
 * @return   the number of leading binary zeros
 */
function leadingZeros(i) {
    if (i === 0) {
        return 32;
    }
    var n = 1;
    if (i >>> 16 === 0) {
        n += 16;
        i <<= 16;
    }
    if (i >>> 24 === 0) {
        n += 8;
        i <<= 8;
    }
    if (i >>> 28 === 0) {
        n += 4;
        i <<= 4;
    }
    if (i >>> 30 === 0) {
        n += 2;
        i <<= 2;
    }
    n -= i >>> 31;
    return n;
}
/**
 * Cheap approximation to a square root.
 *
 * @param value the argument of the square-root function
 * @return      a power of two that approximates the square root of a value
 * @throws      an {@link IllegalArgumentError} if the value is negative
 */
function approximateSquareRoot(value) {
    if (value < 0) {
        throw new errors_1.IllegalArgumentError('Value must be great or equal to 0');
    }
    if (value === 0) {
        return 0;
    }
    var h = 32 - leadingZeros(value);
    return 1 << Math.round(h / 2);
}
exports.approximateSquareRoot = approximateSquareRoot;
/**
 * Find the next integer, equal or higher to the value, which is a power of two.
 *
 * @param value the value to search from
 * @returns     the next power of two
 * @throws      an {@link IllegalArgumentError} if the value is negative or greater than 2^30
 */
function findNextPowerOfTwo(value) {
    if (value < 0 || value > 1 << 30) {
        throw new errors_1.IllegalArgumentError('Illegal argument: ' + value);
    }
    // see: https://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
    value--;
    value |= value >> 1;
    value |= value >> 2;
    value |= value >> 4;
    value |= value >> 8;
    value |= value >> 16;
    value++;
    return value;
}
exports.findNextPowerOfTwo = findNextPowerOfTwo;
/**
 * Maximum 32 bit integer value: 2^32 - 1
 */
exports.MAX_INT32 = 2147483647;
/**
 * Maximum safe integer value for JavaScript numbers: 2^53 - 1
 */
exports.MAX_SAFE_INTEGER = 9007199254740991;
/**
 * Minimum safe integer value for JavaScript numbers: -(2^53 - 1)
 */
exports.MIN_SAFE_INTEGER = -9007199254740991;