| 'use strict'; |
| |
| var GetIntrinsic = require('get-intrinsic'); |
| |
| var $pow = require('math-intrinsics/pow'); |
| |
| var $Number = GetIntrinsic('%Number%'); |
| var $BigInt = GetIntrinsic('%BigInt%', true); |
| |
| module.exports = function bytesAsInteger(rawBytes, elementSize, isUnsigned, isBigInt) { |
| var Z = isBigInt ? $BigInt : $Number; |
| |
| // this is common to both branches |
| var intValue = Z(0); |
| for (var i = 0; i < rawBytes.length; i++) { |
| intValue += Z(rawBytes[i] * $pow(2, 8 * i)); |
| } |
| /* |
| Let intValue be the byte elements of rawBytes concatenated and interpreted as a bit string encoding of an unsigned little-endian binary number. |
| */ |
| |
| if (!isUnsigned) { // steps 5-6 |
| // Let intValue be the byte elements of rawBytes concatenated and interpreted as a bit string encoding of a binary little-endian 2's complement number of bit length elementSize × 8. |
| var bitLength = elementSize * 8; |
| |
| if (rawBytes[elementSize - 1] & 0x80) { |
| intValue -= Z($pow(2, bitLength)); |
| } |
| } |
| |
| return intValue; // step 7 |
| }; |