tools/pbl_crc32.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright 2012 Freescale Semiconductor, Inc.
   4  *
   5  * Cleaned up and refactored by Charles Manning.
   6  */
   7 #include "pblimage.h"
   8
   9 static uint32_t crc_table[256];
  10 static int crc_table_valid;
  11
  12 static void make_crc_table(void)
  13 {
  14         uint32_t mask;
  15         int i, j;
  16         uint32_t poly; /* polynomial exclusive-or pattern */
  17
  18         if (crc_table_valid)
  19                 return;
  20
  21         /*
  22          * the polynomial used by PBL is 1 + x1 + x2 + x4 + x5 + x7 + x8 + x10
  23          * + x11 + x12 + x16 + x22 + x23 + x26 + x32.
  24          */
  25         poly = 0x04c11db7;
  26
  27         for (i = 0; i < 256; i++) {
  28                 mask = i << 24;
  29                 for (j = 0; j < 8; j++) {
  30                         if (mask & 0x80000000)
  31                                 mask = (mask << 1) ^ poly;
  32                         else
  33                                 mask <<= 1;
  34                 }
  35                 crc_table[i] = mask;
  36         }
  37
  38         crc_table_valid = 1;
  39 }
  40
  41 uint32_t pbl_crc32(uint32_t in_crc, const char *buf, uint32_t len)
  42 {
  43         uint32_t crc32_val;
  44         int i;
  45
  46         make_crc_table();
  47
  48         crc32_val = ~in_crc;
  49
  50         for (i = 0; i < len; i++)
  51                 crc32_val = (crc32_val << 8) ^
  52                         crc_table[(crc32_val >> 24) ^ (*buf++ & 0xff)];
  53
  54         return crc32_val;
  55 }