real-time-cpp/code_snippets/chapter17/chapter17_02-001_crc32_mpeg2.c at cece950575da9a74e41d8bb33eb8541bf136f033 · prem7129/real-time-cpp · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
/*//////////////////////////////////////////////////////////*/
/*  Copyright Christopher Kormanyos 2017 - 2023.            */
/*  Distributed under the Boost Software License,           */
/*  Version 1.0. (See accompanying file LICENSE_1_0.txt     */
/*  or copy at http://www.boost.org/LICENSE_1_0.txt)        */
/*//////////////////////////////////////////////////////////*/

/* chapter17_02-001_crc32_mpeg2.c */

/* See also https://godbolt.org/z/PeM54nnEW */

/* This is in a C file. */

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>

uint32_t Crc32_Mpeg2(const uint8_t* DataIn,
                     const size_t DataLength);

uint32_t Crc32_Mpeg2(const uint8_t* DataIn,
                     const size_t DataLength)
{
  /* Name            : CRC32/MPEG-2  */
  /* Polynomial      : 0x04C1'1DB7   */
  /* Initial value   : 0xFFFF'FFFF   */
  /* Test: '1'...'9' : 0x0376'E6E7   */

  /* See also ISO/IEC 13818-1:2000,  */
  /* Recommendation H.222.0 Annex A. */

  /* Set the initial value. */
  uint32_t CrcResult = UINT32_C(0xFFFFFFFF);

  /* Loop counter for iterating through input data */
  size_t LoopCnt;

  /* Loop through the input data stream */
  for(LoopCnt = 0U; LoopCnt < DataLength; ++LoopCnt)
  {
    /* Lookup table for CRC32/MPEG-2 based on 4-bit nibbles */
    static const uint32_t Crc32_Mpeg2_Table[16U] =
    {
      UINT32_C(0x00000000), UINT32_C(0x04C11DB7),
      UINT32_C(0x09823B6E), UINT32_C(0x0D4326D9),
      UINT32_C(0x130476DC), UINT32_C(0x17C56B6B),
      UINT32_C(0x1A864DB2), UINT32_C(0x1E475005),
      UINT32_C(0x2608EDB8), UINT32_C(0x22C9F00F),
      UINT32_C(0x2F8AD6D6), UINT32_C(0x2B4BCB61),
      UINT32_C(0x350C9B64), UINT32_C(0x31CD86D3),
      UINT32_C(0x3C8EA00A), UINT32_C(0x384FBDBD)
    };

    /*current byte from the input */
    const uint8_t DataByte = DataIn[LoopCnt];

    /* Perform the CRC32/MPEG2 algorithm. */

    /* Index for first nibble lookup */
    uint_fast8_t DataIndex =
            (  ((uint_fast8_t) (CrcResult >> 28U))
             ^ ((uint_fast8_t) (DataByte  >>  4U)))
          & UINT8_C(0x0F);


 CrcResult =
        (uint32_t) (  (uint32_t) (CrcResult << 4U)
                    & UINT32_C(0xFFFFFFF0))
      ^ Crc32_Mpeg2_Table[DataIndex];


     DataIndex =
        (((uint_fast8_t) (CrcResult >> 28U))
      ^  ((uint_fast8_t) (DataByte))) & UINT8_C(0x0F);

     CrcResult =
        (uint32_t) (  (uint32_t) (CrcResult << 4U)
                    & UINT32_C(0xFFFFFFF0))
      ^ Crc32_Mpeg2_Table[DataIndex];

  }

  return CrcResult;
}

int main(void)
{
  /* Test data: ASCII values for characters '1' to '9' */
  static const uint8_t TestData[9U] =
  {
    0x31U, 0x32U, 0x33U, 0x34U, 0x35U, 0x36U, 0x37U, 0x38U, 0x39U
  };

  /* Expected CRC32 result for the test data */
  static const uint32_t ControlValue = UINT32_C(0x0376E6E7);

  /* Compute CRC32 result for the test data */
  const uint32_t TestResult = Crc32_Mpeg2(TestData, 9U);

  /* Check if computed result matches expected value */
  const bool TestResultIsOk =
    (bool) ((TestResult == ControlValue) ? true : false);

  if(TestResultIsOk == true)
  {
    printf("CRC32 test result is: OK\n");
  }
  else
  {
    printf("CRC32 test result is: Not OK\n");
  }

  /* Return 0 if test passed, -1 otherwise */
  return ((TestResultIsOk == true) ? 0 : -1);
}