## B.1 CRC-calculation using tables, for the polynomial 0xF4ACFB13

The calculation of a 32-bit CRC signature over an array of N bytes with the help of lookup tables, using “C” as programming language, is shown below:

// VARIANT A: presumably easier to implement on little endian machines

// VARIANT A: presumably easier to implement on little endian machines

uint32_t crctab32[256]; // lookup table

uint32_t CRC32_Backward(char *array, int16_t N){ // input is array of N bytes

									// containing the data, see [Figure 23](#Figure23)

uint32_t result = 1;				// seed value for the calculated CRC-signature

int16_t i;						// index

for(i=N-1;i&gt;=0;i--)				// process array in reversed order

result = crctab32 $((result &gt;&gt; 24) ^ array\[i$) & 0xff\] ^ (result &lt;&lt; 8);

if (result==0)  		return 1; else 		return result;


}

where the lookup-table crctab32 has to be initialized as shown in Table 51.

// VARIANT B: presumably easier to implement on big endian machines

// VARIANT B: presumably easier to implement on big endian machines   uint32_t crctab32[256]; // lookup table   uint32_t CRC32_Forward(char *array, int16_t N){ // input is array of N bytes                                 // containing the data in reversed                                 // order, see e. g. Figure 24      uint32_t result = 1; // seed value for the calculated CRC-signature      int16_t i; // index      for(i=0;i<N;i++) // process array         result = crctab32 [((result >> 24) ^ array[i]) & 0xff] ^ (result << 8);      if (result==0) return 1; else return result;}

where the lookup-table crctab32 has to be initialized as shown in Table 51.

Table 51 – The CRC32 lookup table for 32-bit CRC signature calculations

CRC32 lookup table (0 to 255)
00000000 F4ACFB13 1DF50D35 E959F626 3BEA1A6A CF46E179 261F175F D2B3EC4C
77D434D4 8378CFC7 6A2139E1 9E8DC2F2 4C3E2EBE B892D5AD 51CB238B A567D898
EFA869A8 1B0492BB F25D649D 06F19F8E D44273C2 20EE88D1 C9B77EF7 3D1B85E4
987C5D7C 6CD0A66F 85895049 7125AB5A A3964716 573ABC05 BE634A23 4ACFB130
2BFC2843 DF50D350 36092576 C2A5DE65 10163229 E4BAC93A 0DE33F1C F94FC40F
5C281C97 A884E784 41DD11A2 B571EAB1 67C206FD 936EFDEE 7A370BC8 8E9BF0DB
C45441EB 30F8BAF8 D9A14CDE 2D0DB7CD FFBE5B81 0B12A092 E24B56B4 16E7ADA7
B380753F 472C8E2C AE75780A 5AD98319 886A6F55 7CC69446 959F6260 61339973
57F85086 A354AB95 4A0D5DB3 BEA1A6A0 6C124AEC 98BEB1FF 71E747D9 854BBCCA
202C6452 D4809F41 3DD96967 C9759274 1BC67E38 EF6A852B 0633730D F29F881E
B850392E 4CFCC23D A5A5341B 5109CF08 83BA2344 7716D857 9E4F2E71 6AE3D562
CF840DFA 3B28F6E9 D27100CF 26DDFBDC F46E1790 00C2EC83 E99B1AA5 1D37E1B6
7C0478C5 88A883D6 61F175F0 955D8EE3 47EE62AF B34299BC 5A1B6F9A AEB79489
0BD04C11 FF7CB702 16254124 E289BA37 303A567B C496AD68 2DCF5B4E D963A05D
93AC116D 6700EA7E 8E591C58 7AF5E74B A8460B07 5CEAF014 B5B30632 411FFD21
E47825B9 10D4DEAA F98D288C 0D21D39F DF923FD3 2B3EC4C0 C26732E6 36CBC9F5
AFF0A10C 5B5C5A1F B205AC39 46A9572A 941ABB66 60B64075 89EFB653 7D434D40
D82495D8 2C886ECB C5D198ED 317D63FE E3CE8FB2 176274A1 FE3B8287 0A977994
4058C8A4 B4F433B7 5DADC591 A9013E82 7BB2D2CE 8F1E29DD 6647DFFB 92EB24E8
378CFC70 C3200763 2A79F145 DED50A56 0C66E61A F8CA1D09 1193EB2F E53F103C
840C894F 70A0725C 99F9847A 6D557F69 BFE69325 4B4A6836 A2139E10 56BF6503
F3D8BD9B 07744688 EE2DB0AE 1A814BBD C832A7F1 3C9E5CE2 D5C7AAC4 216B51D7
6BA4E0E7 9F081BF4 7651EDD2 82FD16C1 504EFA8D A4E2019E 4DBBF7B8 B9170CAB
1C70D433 E8DC2F20 0185D906 F5292215 279ACE59 D336354A 3A6FC36C CEC3387F
F808F18A 0CA40A99 E5FDFCBF 115107AC C3E2EBE0 374E10F3 DE17E6D5 2ABB1DC6
8FDCC55E 7B703E4D 9229C86B 66853378 B436DF34 409A2427 A9C3D201 5D6F2912
17A09822 E30C6331 0A559517 FEF96E04 2C4A8248 D8E6795B 31BF8F7D C513746E
6074ACF6 94D857E5 7D81A1C3 892D5AD0 5B9EB69C AF324D8F 466BBBA9 B2C740BA
D3F4D9C9 275822DA CE01D4FC 3AAD2FEF E81EC3A3 1CB238B0 F5EBCE96 01473585
A420ED1D 508C160E B9D5E028 4D791B3B 9FCAF777 6B660C64 823FFA42 76930151
3C5CB061 C8F04B72 21A9BD54 D5054647 07B6AA0B F31A5118 1A43A73E EEEF5C2D
4B8884B5 BF247FA6 567D8980 A2D17293 70629EDF 84CE65CC 6D9793EA 993B68F9
This table contains 32-bit values in hexadecimal representation for each value (0 to 255) of the argument a in the function crctab32 [a]. The table should be used line-by-line in ascending order from top left (0) to bottom right (255). For instance, crctab32[10] is highlighted using a darker background and red color.