RawBytesToNumber.js 2.0 KB

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  1. 'use strict';
  2. var callBound = require('call-bound');
  3. var $RangeError = require('es-errors/range');
  4. var $TypeError = require('es-errors/type');
  5. var $charAt = callBound('String.prototype.charAt');
  6. var $reverse = callBound('Array.prototype.reverse');
  7. var $slice = callBound('Array.prototype.slice');
  8. var hasOwnProperty = require('./HasOwnProperty');
  9. var IsArray = require('./IsArray');
  10. var bytesAsFloat32 = require('../helpers/bytesAsFloat32');
  11. var bytesAsFloat64 = require('../helpers/bytesAsFloat64');
  12. var bytesAsInteger = require('../helpers/bytesAsInteger');
  13. var every = require('../helpers/every');
  14. var isByteValue = require('../helpers/isByteValue');
  15. var tableTAO = require('./tables/typed-array-objects');
  16. // https://262.ecma-international.org/8.0/#sec-rawbytestonumber
  17. module.exports = function RawBytesToNumber(type, rawBytes, isLittleEndian) {
  18. if (typeof type !== 'string' || !hasOwnProperty(tableTAO.size, '$' + type)) {
  19. throw new $TypeError('Assertion failed: `type` must be a TypedArray element type');
  20. }
  21. if (!IsArray(rawBytes) || !every(rawBytes, isByteValue)) {
  22. throw new $TypeError('Assertion failed: `rawBytes` must be an Array of bytes');
  23. }
  24. if (typeof isLittleEndian !== 'boolean') {
  25. throw new $TypeError('Assertion failed: `isLittleEndian` must be a Boolean');
  26. }
  27. var elementSize = tableTAO.size['$' + type]; // step 1
  28. if (rawBytes.length !== elementSize) {
  29. // this assertion is not in the spec, but it'd be an editorial error if it were ever violated
  30. throw new $RangeError('Assertion failed: `rawBytes` must have a length of ' + elementSize + ' for type ' + type);
  31. }
  32. // eslint-disable-next-line no-param-reassign
  33. rawBytes = $slice(rawBytes, 0, elementSize);
  34. if (!isLittleEndian) {
  35. $reverse(rawBytes); // step 2
  36. }
  37. if (type === 'Float32') { // step 3
  38. return bytesAsFloat32(rawBytes);
  39. }
  40. if (type === 'Float64') { // step 4
  41. return bytesAsFloat64(rawBytes);
  42. }
  43. return bytesAsInteger(rawBytes, elementSize, $charAt(type, 0) === 'U', false);
  44. };