package/system/fwtool/src/crc32.h

   1 /*
   2  * Copyright (C) 2016 Felix Fietkau <nbd@nbd.name>
   3  *
   4  * Based on busybox code:
   5  *   CRC32 table fill function
   6  *   Copyright (C) 2006 by Rob Sullivan <cogito.ergo.cogito@gmail.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2
  10  * as published by the Free Software Foundation
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  */
  17 #ifndef __BB_CRC32_H
  18 #define __BB_CRC32_H
  19
  20 static inline void
  21 crc32_filltable(uint32_t *crc_table)
  22 {
  23         uint32_t polynomial = 0xedb88320;
  24         uint32_t c;
  25         int i, j;
  26
  27         for (i = 0; i < 256; i++) {
  28                 c = i;
  29                 for (j = 8; j; j--)
  30                         c = (c&1) ? ((c >> 1) ^ polynomial) : (c >> 1);
  31
  32                 *crc_table++ = c;
  33         }
  34 }
  35
  36 static inline uint32_t
  37 crc32_block(uint32_t val, const void *buf, unsigned len, uint32_t *crc_table)
  38 {
  39         const void *end = (uint8_t*)buf + len;
  40
  41         while (buf != end) {
  42                 val = crc_table[(uint8_t)val ^ *(uint8_t*)buf] ^ (val >> 8);
  43                 buf = (uint8_t*)buf + 1;
  44         }
  45         return val;
  46 }
  47
  48 #endif