thodg/ext4fs/crc32c_table/crc32c_table.c

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• Author : Thomas de Grivel
  Date : 2025-07-08 13:08:20
  Hash : eb3f0b64
  Message : add tests for crc32c from google and chatgpt

• crc32c_table/crc32c_table.c

• /* ext4fs
   * Copyright 2025 kmx.io <contact@kmx.io>
   *
   * Permission is hereby granted to use this software granted the above
   * copyright notice and this permission paragraph are included in all
   * copies and substantial portions of this software.
   *
   * THIS SOFTWARE IS PROVIDED "AS-IS" WITHOUT ANY GUARANTEE OF
   * PURPOSE AND PERFORMANCE. IN NO EVENT WHATSOEVER SHALL THE
   * AUTHOR BE CONSIDERED LIABLE FOR THE USE AND PERFORMANCE OF
   * THIS SOFTWARE.
   */
  #include <stdio.h>
  #include <stdint.h>
  
  #define CRC32C_POLYNOMIAL          0x1EDC6F41U
  #define CRC32C_POLYNOMIAL_REVERSED 0x82F63B78U
  
  int main (void) {
    uint32_t crc;
    uint32_t i;
    uint8_t j;
    printf("/* generated by crc32c_table */\n"
           "static const uint32_t crc32c_table[256] = {\n");
    i = 0;
    while (i < 256) {
      crc = i;
      j = 0;
      while (j < 8) {
        crc = (crc >> 1) ^ (CRC32C_POLYNOMIAL_REVERSED &
                            -(int)(crc & 1));
        j++;
      }
      printf("0x%08X,%s", crc, (i % 4 == 3) ? "\n" : " ");
      i++;
    }
  
    printf("};\n");
    return 0;
  }