70 lines
1.6 KiB
JavaScript
70 lines
1.6 KiB
JavaScript
'use strict';
|
|
|
|
var GetIntrinsic = require('get-intrinsic');
|
|
|
|
var $abs = GetIntrinsic('%Math.abs%');
|
|
var $floor = GetIntrinsic('%Math.floor%');
|
|
var $pow = GetIntrinsic('%Math.pow%');
|
|
|
|
var isFinite = require('./isFinite');
|
|
var isNaN = require('./isNaN');
|
|
var isNegativeZero = require('./isNegativeZero');
|
|
|
|
var maxFiniteFloat32 = 3.4028234663852886e+38; // roughly 2 ** 128 - 1
|
|
|
|
module.exports = function valueToFloat32Bytes(value, isLittleEndian) {
|
|
if (isNaN(value)) {
|
|
return isLittleEndian ? [0, 0, 192, 127] : [127, 192, 0, 0]; // hardcoded
|
|
}
|
|
|
|
var leastSig;
|
|
|
|
if (value === 0) {
|
|
leastSig = isNegativeZero(value) ? 0x80 : 0;
|
|
return isLittleEndian ? [0, 0, 0, leastSig] : [leastSig, 0, 0, 0];
|
|
}
|
|
|
|
if ($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];
|
|
};
|