xahau.js/packages/ripple-binary-codec/src/quality.ts

import { coreTypes } from "./types";
import { Decimal } from "decimal.js";
import * as bigInt from "big-integer";

/**
 * class for encoding and decoding quality
 */
class quality {
  /**
   * Encode quality amount
   *
   * @param arg string representation of an amount
   * @returns Serialized quality
   */
  static encode(quality: string): Buffer {
    const decimal = new Decimal(quality);
    const exponent = decimal.e - 15;
    const qualityString = decimal.times(`1e${-exponent}`).abs().toString();
    const bytes = coreTypes.UInt64.from(bigInt(qualityString)).toBytes();
    bytes[0] = exponent + 100;
    return bytes;
  }

  /**
   * Decode quality amount
   *
   * @param arg hex-string denoting serialized quality
   * @returns deserialized quality
   */
  static decode(quality: string): Decimal {
    const bytes = Buffer.from(quality, "hex").slice(-8);
    const exponent = bytes[0] - 100;
    const mantissa = new Decimal(`0x${bytes.slice(1).toString("hex")}`);
    return mantissa.times(`1e${exponent}`);
  }
}

export { quality };