@oslojs/binary/dist/big.js

Basic primitives for working with binary data

export function bigIntBytes(value) {
    if (value < 0n) {
        value = value * -1n;
    }
    let byteLength = 1;
    while (value > 2n ** BigInt(byteLength * 8) - 1n) {
        byteLength++;
    }
    const encoded = new Uint8Array(byteLength);
    for (let i = 0; i < encoded.byteLength; i++) {
        encoded[i] = Number((value >> BigInt((encoded.byteLength - i - 1) * 8)) & 0xffn);
    }
    return encoded;
}
export function bigIntFromBytes(bytes) {
    if (bytes.byteLength < 1) {
        throw new TypeError("Empty Uint8Array");
    }
    let decoded = 0n;
    for (let i = 0; i < bytes.byteLength; i++) {
        decoded += BigInt(bytes[i]) << BigInt((bytes.byteLength - 1 - i) * 8);
    }
    return decoded;
}