@ledgerhq/hw-app-eth/lib-es/erc20.js

import blob from "@ledgerhq/cryptoassets/data/erc20-signatures";
/**
 * Retrieve the token information by a given contract address if any
 */

export const byContractAddress = contract => get().byContract(asContractAddress(contract));
/**
 * list all the ERC20 tokens informations
 */

export const list = () => get().list();

const asContractAddress = addr => {
  const a = addr.toLowerCase();
  return a.startsWith("0x") ? a : "0x" + a;
}; // this internal get() will lazy load and cache the data from the erc20 data blob


const get = (() => {
  let cache;
  return () => {
    if (cache) return cache;
    const buf = Buffer.from(blob, "base64");
    const byContract = {};
    const entries = [];
    let i = 0;

    while (i < buf.length) {
      const length = buf.readUInt32BE(i);
      i += 4;
      const item = buf.slice(i, i + length);
      let j = 0;
      const tickerLength = item.readUInt8(j);
      j += 1;
      const ticker = item.slice(j, j + tickerLength).toString("ascii");
      j += tickerLength;
      const contractAddress = asContractAddress(item.slice(j, j + 20).toString("hex"));
      j += 20;
      const decimals = item.readUInt32BE(j);
      j += 4;
      const chainId = item.readUInt32BE(j);
      j += 4;
      const signature = item.slice(j);
      const entry = {
        ticker,
        contractAddress,
        decimals,
        chainId,
        signature,
        data: item
      };
      entries.push(entry);
      byContract[contractAddress] = entry;
      i += length;
    }

    const api = {
      list: () => entries,
      byContract: contractAddress => byContract[contractAddress]
    };
    cache = api;
    return api;
  };
})();
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