jsonbinpack/lib/encoder/integer/zigzag.ts

A space-efficient schema-driven binary JSON serialization format based on JSON Schema

/*
 * Copyright 2021 Juan Cruz Viotti
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// See Protocol Buffers' ZigZag encoding definition:
// https://developers.google.com/protocol-buffers/docs/encoding

export const zigzagEncode = (value: bigint): bigint => {
  return value >= BigInt(0)
    ? value * BigInt(2) : (value * BigInt(-2)) - BigInt(1)
}

export const zigzagDecode = (value: bigint): bigint => {
  return value % BigInt(2) === BigInt(0)
    ? value / BigInt(2) : (value + BigInt(1)) / BigInt(-2)
}