@polkadot/util/u8a/toBigInt.js

A collection of useful utilities for @polkadot

import { BigInt } from '@polkadot/x-bigint';
import { _1n } from '../bi/consts.js';
const U8_MAX = BigInt(256);
const U16_MAX = BigInt(256 * 256);
/**
 * @name u8aToBigInt
 * @summary Creates a BigInt from a Uint8Array object.
 */
export function u8aToBigInt(value, { isLe = true, isNegative = false } = {}) {
    if (!value || !value.length) {
        return BigInt(0);
    }
    const u8a = isLe
        ? value
        : value.reverse();
    const dvI = new DataView(u8a.buffer, u8a.byteOffset);
    const mod = u8a.length % 2;
    let result = BigInt(0);
    // This is mostly written for readability (with the single isNegative shortcut),
    // as opposed to performance, e.g. `u8aToBn` does loop unrolling, etc.
    if (isNegative) {
        for (let i = u8a.length - 2; i >= mod; i -= 2) {
            result = (result * U16_MAX) + BigInt(dvI.getUint16(i, true) ^ 0xffff);
        }
        if (mod) {
            result = (result * U8_MAX) + BigInt(dvI.getUint8(0) ^ 0xff);
        }
    }
    else {
        for (let i = u8a.length - 2; i >= mod; i -= 2) {
            result = (result * U16_MAX) + BigInt(dvI.getUint16(i, true));
        }
        if (mod) {
            result = (result * U8_MAX) + BigInt(dvI.getUint8(0));
        }
    }
    return isNegative
        ? ((result * -_1n) - _1n)
        : result;
}