web3-provider-engine/dist/es5/util/rpc-hex-encoding.js

A JavaScript library for composing Ethereum provider objects using middleware modules

"use strict";

var ethUtil = require('@ethereumjs/util');
var assert = require('./assert.js');
module.exports = {
  bufferToQuantityHex: bufferToQuantityHex,
  intToQuantityHex: intToQuantityHex,
  quantityHexToInt: quantityHexToInt
};

/*
 * As per https://github.com/ethereum/wiki/wiki/JSON-RPC#hex-value-encoding
 * Quantities should be represented by the most compact hex representation possible
 * This means that no leading zeroes are allowed. There helpers make it easy
 * to convert to and from integers and their compact hex representation
 */

function bufferToQuantityHex(buffer) {
  buffer = ethUtil.toBuffer(buffer);
  var hex = buffer.toString('hex');
  var trimmed = ethUtil.unpad(hex);
  return ethUtil.addHexPrefix(trimmed);
}
function intToQuantityHex(n) {
  assert(typeof n === 'number' && n === Math.floor(n), 'intToQuantityHex arg must be an integer');
  var nHex = ethUtil.toBuffer(n).toString('hex');
  if (nHex[0] === '0') {
    nHex = nHex.substring(1);
  }
  return ethUtil.addHexPrefix(nHex);
}
function quantityHexToInt(prefixedQuantityHex) {
  assert(typeof prefixedQuantityHex === 'string', 'arg to quantityHexToInt must be a string');
  var quantityHex = ethUtil.stripHexPrefix(prefixedQuantityHex);
  var isEven = quantityHex.length % 2 === 0;
  if (!isEven) {
    quantityHex = '0' + quantityHex;
  }
  var buf = Buffer.from(quantityHex, 'hex');
  return ethUtil.bufferToInt(buf);
}