es.data-view.get-float16.js 1.2 KB

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  1. 'use strict';
  2. var $ = require('../internals/export');
  3. var uncurryThis = require('../internals/function-uncurry-this');
  4. var pow = Math.pow;
  5. var EXP_MASK16 = 31; // 2 ** 5 - 1
  6. var SIGNIFICAND_MASK16 = 1023; // 2 ** 10 - 1
  7. var MIN_SUBNORMAL16 = pow(2, -24); // 2 ** -10 * 2 ** -14
  8. var SIGNIFICAND_DENOM16 = 0.0009765625; // 2 ** -10
  9. var unpackFloat16 = function (bytes) {
  10. var sign = bytes >>> 15;
  11. var exponent = bytes >>> 10 & EXP_MASK16;
  12. var significand = bytes & SIGNIFICAND_MASK16;
  13. if (exponent === EXP_MASK16) return significand === 0 ? (sign === 0 ? Infinity : -Infinity) : NaN;
  14. if (exponent === 0) return significand * (sign === 0 ? MIN_SUBNORMAL16 : -MIN_SUBNORMAL16);
  15. return pow(2, exponent - 15) * (sign === 0 ? 1 + significand * SIGNIFICAND_DENOM16 : -1 - significand * SIGNIFICAND_DENOM16);
  16. };
  17. // eslint-disable-next-line es/no-typed-arrays -- safe
  18. var getUint16 = uncurryThis(DataView.prototype.getUint16);
  19. // `DataView.prototype.getFloat16` method
  20. // https://tc39.es/ecma262/#sec-dataview.prototype.getfloat16
  21. $({ target: 'DataView', proto: true }, {
  22. getFloat16: function getFloat16(byteOffset /* , littleEndian */) {
  23. var uint16 = getUint16(this, byteOffset, arguments.length > 1 ? arguments[1] : false);
  24. return unpackFloat16(uint16);
  25. }
  26. });