FastCRCsw.cpp

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/* FastCRC library code is placed under the MIT license
 * Copyright (c) 2014,2015,2016 Frank Bosing
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

//
// Thanks to:
// - Catalogue of parametrised CRC algorithms, CRC RevEng
// http://reveng.sourceforge.net/crc-catalogue/
//
// - Danjel McGougan (CRC-Table-Generator)
//

//
// modify from FastCRC library @ 2018/11/20
//

#include "FastCRC.h"
#include "FastCRC_tables.hpp"

// ================= 16-BIT CRC ===================
FastCRC16::FastCRC16(uint16_t seed) { seed_ = seed; }

#define crc_n4(crc, data, table)                                               \
  crc ^= data;                                                                 \
  crc = (table[(crc & 0xff) + 0x300]) ^ (table[((crc >> 8) & 0xff) + 0x200]) ^ \
        (table[((data >> 16) & 0xff) + 0x100]) ^ (table[data >> 24]);

uint16_t FastCRC16::mcrf4xx_calc(const uint8_t *data, uint16_t len) {
  uint16_t crc = seed_;

  while (((uintptr_t)data & 3) && len) {
    crc = (crc >> 8) ^ crc_table_mcrf4xx[(crc & 0xff) ^ *data++];
    len--;
  }

  while (len >= 16) {
    len -= 16;
    crc_n4(crc, ((uint32_t *)data)[0], crc_table_mcrf4xx);
    crc_n4(crc, ((uint32_t *)data)[1], crc_table_mcrf4xx);
    crc_n4(crc, ((uint32_t *)data)[2], crc_table_mcrf4xx);
    crc_n4(crc, ((uint32_t *)data)[3], crc_table_mcrf4xx);
    data += 16;
  }

  while (len--) {
    crc = (crc >> 8) ^ crc_table_mcrf4xx[(crc & 0xff) ^ *data++];
  }

  // seed = crc;
  return crc;
}

// ================= 32-BIT CRC ===================
FastCRC32::FastCRC32(uint32_t seed) { seed_ = seed; }

#define crc_n4d(crc, data, table)                                              \
  crc ^= data;                                                                 \
  crc = (table[(crc & 0xff) + 0x300]) ^ (table[((crc >> 8) & 0xff) + 0x200]) ^ \
        (table[((crc >> 16) & 0xff) + 0x100]) ^ (table[(crc >> 24) & 0xff]);

#define crcsm_n4d(crc, data, table)       \
  crc ^= data;                            \
  crc = (crc >> 8) ^ (table[crc & 0xff]); \
  crc = (crc >> 8) ^ (table[crc & 0xff]); \
  crc = (crc >> 8) ^ (table[crc & 0xff]); \
  crc = (crc >> 8) ^ (table[crc & 0xff]);

#if CRC_BIGTABLES
#define CRC_TABLE_CRC32 crc_table_crc32_big
#else
#define CRC_TABLE_CRC32 crc_table_crc32
#endif

uint32_t FastCRC32::crc32_calc(const uint8_t *data, uint16_t len) {
  uint32_t crc = seed_ ^ 0xffffffff;

  while (((uintptr_t)data & 3) && len) {
    crc = (crc >> 8) ^ CRC_TABLE_CRC32[(crc & 0xff) ^ *data++];
    len--;
  }

  while (len >= 16) {
    len -= 16;
#if CRC_BIGTABLES
    crc_n4d(crc, ((uint32_t *)data)[0], CRC_TABLE_CRC32);
    crc_n4d(crc, ((uint32_t *)data)[1], CRC_TABLE_CRC32);
    crc_n4d(crc, ((uint32_t *)data)[2], CRC_TABLE_CRC32);
    crc_n4d(crc, ((uint32_t *)data)[3], CRC_TABLE_CRC32);
#else
    crcsm_n4d(crc, ((uint32_t *)data)[0], CRC_TABLE_CRC32);
    crcsm_n4d(crc, ((uint32_t *)data)[1], CRC_TABLE_CRC32);
    crcsm_n4d(crc, ((uint32_t *)data)[2], CRC_TABLE_CRC32);
    crcsm_n4d(crc, ((uint32_t *)data)[3], CRC_TABLE_CRC32);
#endif
    data += 16;
  }

  while (len--) {
    crc = (crc >> 8) ^ CRC_TABLE_CRC32[(crc & 0xff) ^ *data++];
  }

  // seed = crc;
  crc ^= 0xffffffff;

  return crc;
}