/*
   * Copyright 2016 Freie Universität Berlin
   * Copyright 2016 Ludwig Knüpfer <ludwig.knuepfer@fu-berlin.de>
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @defgroup    sys_checksum Checksum
   * @ingroup     sys
   * @brief       Checksum function libraries
   *
   * This module provides a number of checksum functions. Most notably is the
   * @ref sys_checksum_crc16_ccitt and the @ref sys_checksum_ucrc16 modules which
   * provide support for the CRC16 checksum.
   *
   * @ref sys_checksum_crc16_ccitt only provides an implementation of the CCITT
   * flavor of CRC16 (polynomial @$ x^{16} + x^{12} + x^{5} + 1 @$) for big-endian
   * numbers with starting seed `0x1d0f` (though others can be provided), while
   * @ref sys_checksum_ucrc16 is more generalized, since it takes the
   * hexadecimal representation of the polynomial as a parameter and provides
   * functions and standardized polynomials for both big- and little-endian
   * numbers.
   *
   * The caveat of @ref sys_checksum_ucrc16 is that it is significantly slower
   * (approximately factor 8) than @ref sys_checksum_crc16_ccitt since the latter
   * is able to calculate the checksum byte-wise, while the first calculates
   * needs to calculate it bit-wise. @ref sys_checksum_crc16_ccitt achieves this
   * advantage by using a look-up table that provides the checksum for every
   * possible byte-value. It thus trades of memory against speed. If your
   * platform is rather small equipped in memory you should prefer the
   * @ref sys_checksum_ucrc16 version.
   */