tools/pbl_crc32.c

   1 /*
   2  * Copyright 2012 Freescale Semiconductor, Inc.
   3  *
   4  * Cleaned up and refactored by Charles Manning.
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  */
   8 #include "pblimage.h"
   9
  10 static uint32_t crc_table[256];
  11 static int crc_table_valid;
  12
  13 static void make_crc_table(void)
  14 {
  15         uint32_t mask;
  16         int i, j;
  17         uint32_t poly; /* polynomial exclusive-or pattern */
  18
  19         if (crc_table_valid)
  20                 return;
  21
  22         /*
  23          * the polynomial used by PBL is 1 + x1 + x2 + x4 + x5 + x7 + x8 + x10
  24          * + x11 + x12 + x16 + x22 + x23 + x26 + x32.
  25          */
  26         poly = 0x04c11db7;
  27
  28         for (i = 0; i < 256; i++) {
  29                 mask = i << 24;
  30                 for (j = 0; j < 8; j++) {
  31                         if (mask & 0x80000000)
  32                                 mask = (mask << 1) ^ poly;
  33                         else
  34                                 mask <<= 1;
  35                 }
  36                 crc_table[i] = mask;
  37         }
  38
  39         crc_table_valid = 1;
  40 }
  41
  42 uint32_t pbl_crc32(uint32_t in_crc, const char *buf, uint32_t len)
  43 {
  44         uint32_t crc32_val;
  45         int i;
  46
  47         make_crc_table();
  48
  49         crc32_val = ~in_crc;
  50
  51         for (i = 0; i < len; i++)
  52                 crc32_val = (crc32_val << 8) ^
  53                         crc_table[(crc32_val >> 24) ^ (*buf++ & 0xff)];
  54
  55         return crc32_val;
  56 }