@Override
    public PoWSolution hash(
        final long nonce,
        final long number,
        final EpochCalculator epochCalc,
        final Bytes prePowHash) {
      final EthHashCacheFactory.EthHashDescriptor cache =
          cacheFactory.ethHashCacheFor(number, epochCalc);
      final PoWSolution solution =
          EthHash.hashimotoLight(cache.getDatasetSize(), cache.getCache(), prePowHash, nonce);
      return solution;
    }
Implementation of Ethash Hashimoto Light Implementation.
ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/PoWHasher.java