source: imaps-frontend/node_modules/es-abstract/helpers/bytesAsInteger.js

'use strict';

var GetIntrinsic = require('get-intrinsic');

var $pow = GetIntrinsic('%Math.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
};