73 lines
2.1 KiB
JavaScript
73 lines
2.1 KiB
JavaScript
'use strict';
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var callBound = require('call-bind/callBound');
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var $RangeError = require('es-errors/range');
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var $TypeError = require('es-errors/type');
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var $charAt = callBound('String.prototype.charAt');
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var $reverse = callBound('Array.prototype.reverse');
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var $slice = callBound('Array.prototype.slice');
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var hasOwnProperty = require('./HasOwnProperty');
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var IsArray = require('./IsArray');
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var bytesAsFloat32 = require('../helpers/bytesAsFloat32');
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var bytesAsFloat64 = require('../helpers/bytesAsFloat64');
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var bytesAsInteger = require('../helpers/bytesAsInteger');
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var every = require('../helpers/every');
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var isByteValue = require('../helpers/isByteValue');
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var keys = require('object-keys');
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// https://262.ecma-international.org/8.0/#table-50
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var TypeToSizes = {
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__proto__: null,
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Int8: 1,
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Uint8: 1,
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Uint8C: 1,
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Int16: 2,
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Uint16: 2,
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Int32: 4,
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Uint32: 4,
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Float32: 4,
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Float64: 8
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};
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// https://262.ecma-international.org/8.0/#sec-rawbytestonumber
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module.exports = function RawBytesToNumber(type, rawBytes, isLittleEndian) {
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if (typeof type !== 'string' || !hasOwnProperty(TypeToSizes, type)) {
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throw new $TypeError('Assertion failed: `type` must be a TypedArray element type: ' + keys(TypeToSizes));
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}
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if (!IsArray(rawBytes) || !every(rawBytes, isByteValue)) {
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throw new $TypeError('Assertion failed: `rawBytes` must be an Array of bytes');
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}
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if (typeof isLittleEndian !== 'boolean') {
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throw new $TypeError('Assertion failed: `isLittleEndian` must be a Boolean');
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}
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var elementSize = TypeToSizes[type]; // step 1
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if (rawBytes.length !== elementSize) {
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// this assertion is not in the spec, but it'd be an editorial error if it were ever violated
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throw new $RangeError('Assertion failed: `rawBytes` must have a length of ' + elementSize + ' for type ' + type);
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}
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// eslint-disable-next-line no-param-reassign
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rawBytes = $slice(rawBytes, 0, elementSize);
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if (!isLittleEndian) {
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$reverse(rawBytes); // step 2
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}
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if (type === 'Float32') { // step 3
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return bytesAsFloat32(rawBytes);
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}
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if (type === 'Float64') { // step 4
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return bytesAsFloat64(rawBytes);
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}
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return bytesAsInteger(rawBytes, elementSize, $charAt(type, 0) === 'U', false);
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};
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