2 * Based on file found here:
4 * https://svnweb.freebsd.org/base/stable/10/sys/libkern/crc32.c?revision=256281
8 * COPYRIGHT (C) 1986 Gary S. Brown. You may use this program, or
9 * code or tables extracted from it, as desired without restriction.
13 * First, the polynomial itself and its table of feedback terms. The
15 * X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0
17 * Note that we take it "backwards" and put the highest-order term in
18 * the lowest-order bit. The X^32 term is "implied"; the LSB is the
19 * X^31 term, etc. The X^0 term (usually shown as "+1") results in
22 * Note that the usual hardware shift register implementation, which
23 * is what we're using (we're merely optimizing it by doing eight-bit
24 * chunks at a time) shifts bits into the lowest-order term. In our
25 * implementation, that means shifting towards the right. Why do we
26 * do it this way? Because the calculated CRC must be transmitted in
27 * order from highest-order term to lowest-order term. UARTs transmit
28 * characters in order from LSB to MSB. By storing the CRC this way
29 * we hand it to the UART in the order low-byte to high-byte; the UART
30 * sends each low-bit to hight-bit; and the result is transmission bit
31 * by bit from highest- to lowest-order term without requiring any bit
32 * shuffling on our part. Reception works similarly
34 * The feedback terms table consists of 256, 32-bit entries. Notes
36 * The table can be generated at runtime if desired; code to do so
37 * is shown later. It might not be obvious, but the feedback
38 * terms simply represent the results of eight shift/xor opera
39 * tions for all combinations of data and CRC register values
41 * The values must be right-shifted by eight bits by the "updcrc
42 * logic; the shift must be unsigned (bring in zeroes). On some
43 * hardware you could probably optimize the shift in assembler by
44 * using byte-swap instructions
45 * polynomial $edb88320
48 * CRC32 code derived from work by Gary S. Brown.
53 /* CRC32C routines, these use a different polynomial */
54 /*****************************************************************/
56 /* CRC LOOKUP TABLE */
57 /* ================ */
58 /* The following CRC lookup table was generated automagically */
59 /* by the Rocksoft^tm Model CRC Algorithm Table Generation */
60 /* Program V1.0 using the following model parameters: */
62 /* Width : 4 bytes. */
63 /* Poly : 0x1EDC6F41L */
66 /* For more information on the Rocksoft^tm Model CRC Algorithm, */
67 /* see the document titled "A Painless Guide to CRC Error */
68 /* Detection Algorithms" by Ross Williams */
69 /* (ross@guest.adelaide.edu.au.). This document is likely to be */
70 /* in the FTP archive "ftp.adelaide.edu.au/pub/rocksoft". */
72 /*****************************************************************/
74 static const uint32_t crc32Table
[256] = {
75 0x00000000L
, 0xF26B8303L
, 0xE13B70F7L
, 0x1350F3F4L
,
76 0xC79A971FL
, 0x35F1141CL
, 0x26A1E7E8L
, 0xD4CA64EBL
,
77 0x8AD958CFL
, 0x78B2DBCCL
, 0x6BE22838L
, 0x9989AB3BL
,
78 0x4D43CFD0L
, 0xBF284CD3L
, 0xAC78BF27L
, 0x5E133C24L
,
79 0x105EC76FL
, 0xE235446CL
, 0xF165B798L
, 0x030E349BL
,
80 0xD7C45070L
, 0x25AFD373L
, 0x36FF2087L
, 0xC494A384L
,
81 0x9A879FA0L
, 0x68EC1CA3L
, 0x7BBCEF57L
, 0x89D76C54L
,
82 0x5D1D08BFL
, 0xAF768BBCL
, 0xBC267848L
, 0x4E4DFB4BL
,
83 0x20BD8EDEL
, 0xD2D60DDDL
, 0xC186FE29L
, 0x33ED7D2AL
,
84 0xE72719C1L
, 0x154C9AC2L
, 0x061C6936L
, 0xF477EA35L
,
85 0xAA64D611L
, 0x580F5512L
, 0x4B5FA6E6L
, 0xB93425E5L
,
86 0x6DFE410EL
, 0x9F95C20DL
, 0x8CC531F9L
, 0x7EAEB2FAL
,
87 0x30E349B1L
, 0xC288CAB2L
, 0xD1D83946L
, 0x23B3BA45L
,
88 0xF779DEAEL
, 0x05125DADL
, 0x1642AE59L
, 0xE4292D5AL
,
89 0xBA3A117EL
, 0x4851927DL
, 0x5B016189L
, 0xA96AE28AL
,
90 0x7DA08661L
, 0x8FCB0562L
, 0x9C9BF696L
, 0x6EF07595L
,
91 0x417B1DBCL
, 0xB3109EBFL
, 0xA0406D4BL
, 0x522BEE48L
,
92 0x86E18AA3L
, 0x748A09A0L
, 0x67DAFA54L
, 0x95B17957L
,
93 0xCBA24573L
, 0x39C9C670L
, 0x2A993584L
, 0xD8F2B687L
,
94 0x0C38D26CL
, 0xFE53516FL
, 0xED03A29BL
, 0x1F682198L
,
95 0x5125DAD3L
, 0xA34E59D0L
, 0xB01EAA24L
, 0x42752927L
,
96 0x96BF4DCCL
, 0x64D4CECFL
, 0x77843D3BL
, 0x85EFBE38L
,
97 0xDBFC821CL
, 0x2997011FL
, 0x3AC7F2EBL
, 0xC8AC71E8L
,
98 0x1C661503L
, 0xEE0D9600L
, 0xFD5D65F4L
, 0x0F36E6F7L
,
99 0x61C69362L
, 0x93AD1061L
, 0x80FDE395L
, 0x72966096L
,
100 0xA65C047DL
, 0x5437877EL
, 0x4767748AL
, 0xB50CF789L
,
101 0xEB1FCBADL
, 0x197448AEL
, 0x0A24BB5AL
, 0xF84F3859L
,
102 0x2C855CB2L
, 0xDEEEDFB1L
, 0xCDBE2C45L
, 0x3FD5AF46L
,
103 0x7198540DL
, 0x83F3D70EL
, 0x90A324FAL
, 0x62C8A7F9L
,
104 0xB602C312L
, 0x44694011L
, 0x5739B3E5L
, 0xA55230E6L
,
105 0xFB410CC2L
, 0x092A8FC1L
, 0x1A7A7C35L
, 0xE811FF36L
,
106 0x3CDB9BDDL
, 0xCEB018DEL
, 0xDDE0EB2AL
, 0x2F8B6829L
,
107 0x82F63B78L
, 0x709DB87BL
, 0x63CD4B8FL
, 0x91A6C88CL
,
108 0x456CAC67L
, 0xB7072F64L
, 0xA457DC90L
, 0x563C5F93L
,
109 0x082F63B7L
, 0xFA44E0B4L
, 0xE9141340L
, 0x1B7F9043L
,
110 0xCFB5F4A8L
, 0x3DDE77ABL
, 0x2E8E845FL
, 0xDCE5075CL
,
111 0x92A8FC17L
, 0x60C37F14L
, 0x73938CE0L
, 0x81F80FE3L
,
112 0x55326B08L
, 0xA759E80BL
, 0xB4091BFFL
, 0x466298FCL
,
113 0x1871A4D8L
, 0xEA1A27DBL
, 0xF94AD42FL
, 0x0B21572CL
,
114 0xDFEB33C7L
, 0x2D80B0C4L
, 0x3ED04330L
, 0xCCBBC033L
,
115 0xA24BB5A6L
, 0x502036A5L
, 0x4370C551L
, 0xB11B4652L
,
116 0x65D122B9L
, 0x97BAA1BAL
, 0x84EA524EL
, 0x7681D14DL
,
117 0x2892ED69L
, 0xDAF96E6AL
, 0xC9A99D9EL
, 0x3BC21E9DL
,
118 0xEF087A76L
, 0x1D63F975L
, 0x0E330A81L
, 0xFC588982L
,
119 0xB21572C9L
, 0x407EF1CAL
, 0x532E023EL
, 0xA145813DL
,
120 0x758FE5D6L
, 0x87E466D5L
, 0x94B49521L
, 0x66DF1622L
,
121 0x38CC2A06L
, 0xCAA7A905L
, 0xD9F75AF1L
, 0x2B9CD9F2L
,
122 0xFF56BD19L
, 0x0D3D3E1AL
, 0x1E6DCDEEL
, 0xEC064EEDL
,
123 0xC38D26C4L
, 0x31E6A5C7L
, 0x22B65633L
, 0xD0DDD530L
,
124 0x0417B1DBL
, 0xF67C32D8L
, 0xE52CC12CL
, 0x1747422FL
,
125 0x49547E0BL
, 0xBB3FFD08L
, 0xA86F0EFCL
, 0x5A048DFFL
,
126 0x8ECEE914L
, 0x7CA56A17L
, 0x6FF599E3L
, 0x9D9E1AE0L
,
127 0xD3D3E1ABL
, 0x21B862A8L
, 0x32E8915CL
, 0xC083125FL
,
128 0x144976B4L
, 0xE622F5B7L
, 0xF5720643L
, 0x07198540L
,
129 0x590AB964L
, 0xAB613A67L
, 0xB831C993L
, 0x4A5A4A90L
,
130 0x9E902E7BL
, 0x6CFBAD78L
, 0x7FAB5E8CL
, 0x8DC0DD8FL
,
131 0xE330A81AL
, 0x115B2B19L
, 0x020BD8EDL
, 0xF0605BEEL
,
132 0x24AA3F05L
, 0xD6C1BC06L
, 0xC5914FF2L
, 0x37FACCF1L
,
133 0x69E9F0D5L
, 0x9B8273D6L
, 0x88D28022L
, 0x7AB90321L
,
134 0xAE7367CAL
, 0x5C18E4C9L
, 0x4F48173DL
, 0xBD23943EL
,
135 0xF36E6F75L
, 0x0105EC76L
, 0x12551F82L
, 0xE03E9C81L
,
136 0x34F4F86AL
, 0xC69F7B69L
, 0xD5CF889DL
, 0x27A40B9EL
,
137 0x79B737BAL
, 0x8BDCB4B9L
, 0x988C474DL
, 0x6AE7C44EL
,
138 0xBE2DA0A5L
, 0x4C4623A6L
, 0x5F16D052L
, 0xAD7D5351L
141 // NOTE: See source URL at top of this file for multitable implementation which
142 // offers a performance boost at the cost of ~8KB of static tables.
145 ComputeCrc32c(uint32_t crc
, const void *buf
, size_t size
)
147 const uint8_t *p
= buf
;
151 crc
= crc32Table
[(crc
^ *p
++) & 0xff] ^ (crc
>> 8);