source: imaps-frontend/node_modules/es-abstract/helpers/valueToFloat32Bytes.js@ 79a0317

'use strict';

var $abs = require('math-intrinsics/abs');
var $floor = require('math-intrinsics/floor');
var $pow = require('math-intrinsics/pow');

var isFinite = require('math-intrinsics/isFinite');
var isNaN = require('math-intrinsics/isNaN');
var isNegativeZero = require('math-intrinsics/isNegativeZero');

var maxFiniteFloat32 = 3.4028234663852886e+38; // roughly 2 ** 128 - 1

module.exports = function valueToFloat32Bytes(value, isLittleEndian) {
        if (isNaN(value)) {
                return isLittleEndian ? [0, 0, 192, 127] : [127, 192, 0, 0]; // hardcoded
        }

        var leastSig;

        if (value === 0) {
                leastSig = isNegativeZero(value) ? 0x80 : 0;
                return isLittleEndian ? [0, 0, 0, leastSig] : [leastSig, 0, 0, 0];
        }

        if ($abs(value) > maxFiniteFloat32 || !isFinite(value)) {
                leastSig = value < 0 ? 255 : 127;
                return isLittleEndian ? [0, 0, 128, leastSig] : [leastSig, 128, 0, 0];
        }

        var sign = value < 0 ? 1 : 0;
        value = $abs(value); // eslint-disable-line no-param-reassign

        var exponent = 0;
        while (value >= 2) {
                exponent += 1;
                value /= 2; // eslint-disable-line no-param-reassign
        }

        while (value < 1) {
                exponent -= 1;
                value *= 2; // eslint-disable-line no-param-reassign
        }

        var mantissa = value - 1;
        mantissa *= $pow(2, 23) + 0.5;
        mantissa = $floor(mantissa);

        exponent += 127;
        exponent <<= 23;

        var result = (sign << 31)
        | exponent
        | mantissa;

        var byte0 = result & 255;
        result >>= 8;
        var byte1 = result & 255;
        result >>= 8;
        var byte2 = result & 255;
        result >>= 8;
        var byte3 = result & 255;

        if (isLittleEndian) {
                return [byte0, byte1, byte2, byte3];
        }
        return [byte3, byte2, byte1, byte0];
};