1 | 'use strict';
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2 |
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3 | var GetIntrinsic = require('get-intrinsic');
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4 |
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5 | var $abs = GetIntrinsic('%Math.abs%');
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6 | var $floor = GetIntrinsic('%Math.floor%');
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7 | var $pow = GetIntrinsic('%Math.pow%');
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8 |
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9 | var isFinite = require('./isFinite');
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10 | var isNaN = require('./isNaN');
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11 | var isNegativeZero = require('./isNegativeZero');
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12 |
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13 | var maxFiniteFloat32 = 3.4028234663852886e+38; // roughly 2 ** 128 - 1
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14 |
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15 | module.exports = function valueToFloat32Bytes(value, isLittleEndian) {
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16 | if (isNaN(value)) {
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17 | return isLittleEndian ? [0, 0, 192, 127] : [127, 192, 0, 0]; // hardcoded
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18 | }
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19 |
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20 | var leastSig;
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21 |
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22 | if (value === 0) {
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23 | leastSig = isNegativeZero(value) ? 0x80 : 0;
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24 | return isLittleEndian ? [0, 0, 0, leastSig] : [leastSig, 0, 0, 0];
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25 | }
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26 |
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27 | if ($abs(value) > maxFiniteFloat32 || !isFinite(value)) {
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28 | leastSig = value < 0 ? 255 : 127;
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29 | return isLittleEndian ? [0, 0, 128, leastSig] : [leastSig, 128, 0, 0];
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30 | }
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31 |
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32 | var sign = value < 0 ? 1 : 0;
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33 | value = $abs(value); // eslint-disable-line no-param-reassign
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34 |
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35 | var exponent = 0;
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36 | while (value >= 2) {
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37 | exponent += 1;
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38 | value /= 2; // eslint-disable-line no-param-reassign
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39 | }
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40 |
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41 | while (value < 1) {
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42 | exponent -= 1;
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43 | value *= 2; // eslint-disable-line no-param-reassign
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44 | }
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45 |
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46 | var mantissa = value - 1;
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47 | mantissa *= $pow(2, 23) + 0.5;
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48 | mantissa = $floor(mantissa);
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49 |
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50 | exponent += 127;
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51 | exponent <<= 23;
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52 |
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53 | var result = (sign << 31)
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54 | | exponent
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55 | | mantissa;
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56 |
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57 | var byte0 = result & 255;
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58 | result >>= 8;
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59 | var byte1 = result & 255;
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60 | result >>= 8;
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61 | var byte2 = result & 255;
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62 | result >>= 8;
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63 | var byte3 = result & 255;
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64 |
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65 | if (isLittleEndian) {
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66 | return [byte0, byte1, byte2, byte3];
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67 | }
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68 | return [byte3, byte2, byte1, byte0];
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69 | };
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