Line data    Source code

       1              : /* SPDX-License-Identifier: Zlib */
       2              : 
       3              : /*
       4              :  * CRC32 checksum
       5              :  *
       6              :  * Copyright (c) 1998-2019 Joergen Ibsen
       7              :  *
       8              :  * This software is provided 'as-is', without any express or implied
       9              :  * warranty. In no event will the authors be held liable for any damages
      10              :  * arising from the use of this software.
      11              :  *
      12              :  * Permission is granted to anyone to use this software for any purpose,
      13              :  * including commercial applications, and to alter it and redistribute it
      14              :  * freely, subject to the following restrictions:
      15              :  *
      16              :  *   1. The origin of this software must not be misrepresented; you must
      17              :  *      not claim that you wrote the original software. If you use this
      18              :  *      software in a product, an acknowledgment in the product
      19              :  *      documentation would be appreciated but is not required.
      20              :  *
      21              :  *   2. Altered source versions must be plainly marked as such, and must
      22              :  *      not be misrepresented as being the original software.
      23              :  *
      24              :  *   3. This notice may not be removed or altered from any source
      25              :  *      distribution.
      26              :  */
      27              : 
      28              : /*
      29              :  * CRC32 algorithm taken from the zlib source, which is
      30              :  * Copyright (C) 1995-1998 Jean-loup Gailly and Mark Adler
      31              :  */
      32              : 
      33              : #include "tinf.h"
      34              : 
      35              : static const unsigned int tinf_crc32tab[16] = {
      36              :         0x00000000, 0x1DB71064, 0x3B6E20C8, 0x26D930AC, 0x76DC4190,
      37              :         0x6B6B51F4, 0x4DB26158, 0x5005713C, 0xEDB88320, 0xF00F9344,
      38              :         0xD6D6A3E8, 0xCB61B38C, 0x9B64C2B0, 0x86D3D2D4, 0xA00AE278,
      39              :         0xBDBDF21C
      40              : };
      41              : 
      42           10 : unsigned int tinf_crc32(const void *data, unsigned int length)
      43              : {
      44           10 :         const unsigned char *buf = (const unsigned char *) data;
      45           10 :         unsigned int crc = 0xFFFFFFFF;
      46              :         unsigned int i;
      47              : 
      48           10 :         if (length == 0) {
      49            0 :                 return 0;
      50              :         }
      51              : 
      52       109864 :         for (i = 0; i < length; ++i) {
      53       109854 :                 crc ^= buf[i];
      54       109854 :                 crc = tinf_crc32tab[crc & 0x0F] ^ (crc >> 4);
      55       109854 :                 crc = tinf_crc32tab[crc & 0x0F] ^ (crc >> 4);
      56              :         }
      57              : 
      58           10 :         return crc ^ 0xFFFFFFFF;
      59              : }