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97025b23 JS |
1 | /*- |
2 | * COPYRIGHT (C) 1986 Gary S. Brown. You may use this program, or | |
3 | * code or tables extracted from it, as desired without restriction. | |
4 | */ | |
5 | ||
6 | /* | |
7 | * First, the polynomial itself and its table of feedback terms. The | |
8 | * polynomial is | |
9 | * 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 | |
10 | * | |
11 | * Note that we take it "backwards" and put the highest-order term in | |
12 | * the lowest-order bit. The X^32 term is "implied"; the LSB is the | |
13 | * X^31 term, etc. The X^0 term (usually shown as "+1") results in | |
14 | * the MSB being 1 | |
15 | * | |
16 | * Note that the usual hardware shift register implementation, which | |
17 | * is what we're using (we're merely optimizing it by doing eight-bit | |
18 | * chunks at a time) shifts bits into the lowest-order term. In our | |
19 | * implementation, that means shifting towards the right. Why do we | |
20 | * do it this way? Because the calculated CRC must be transmitted in | |
21 | * order from highest-order term to lowest-order term. UARTs transmit | |
22 | * characters in order from LSB to MSB. By storing the CRC this way | |
23 | * we hand it to the UART in the order low-byte to high-byte; the UART | |
24 | * sends each low-bit to hight-bit; and the result is transmission bit | |
25 | * by bit from highest- to lowest-order term without requiring any bit | |
26 | * shuffling on our part. Reception works similarly | |
27 | * | |
28 | * The feedback terms table consists of 256, 32-bit entries. Notes | |
29 | * | |
30 | * The table can be generated at runtime if desired; code to do so | |
31 | * can be found in FreeBSD. It might not be obvious, but the feedback | |
32 | * terms simply represent the results of eight shift/xor opera | |
33 | * tions for all combinations of data and CRC register values | |
34 | * | |
35 | * The values must be right-shifted by eight bits by the "updcrc | |
36 | * logic; the shift must be unsigned (bring in zeroes). On some | |
37 | * hardware you could probably optimize the shift in assembler by | |
38 | * using byte-swap instructions | |
39 | * polynomial $edb88320 | |
40 | * | |
41 | * | |
42 | * CRC32 code derived from work by Gary S. Brown. | |
43 | */ | |
44 | ||
45 | #include <config.h> | |
46 | #include "crc32c.h" | |
47 | #include "byte-order.h" | |
48 | ||
49 | /*****************************************************************/ | |
50 | /* */ | |
51 | /* CRC LOOKUP TABLE */ | |
52 | /* ================ */ | |
53 | /* The following CRC lookup table was generated automagically */ | |
54 | /* by the Rocksoft^tm Model CRC Algorithm Table Generation */ | |
55 | /* Program V1.0 using the following model parameters: */ | |
56 | /* */ | |
57 | /* Width : 4 bytes. */ | |
58 | /* Poly : 0x1EDC6F41L */ | |
59 | /* Reverse : TRUE. */ | |
60 | /* */ | |
61 | /* For more information on the Rocksoft^tm Model CRC Algorithm, */ | |
62 | /* see the document titled "A Painless Guide to CRC Error */ | |
63 | /* Detection Algorithms" by Ross Williams */ | |
64 | /* (ross@guest.adelaide.edu.au.). This document is likely to be */ | |
65 | /* in the FTP archive "ftp.adelaide.edu.au/pub/rocksoft". */ | |
66 | /* */ | |
67 | /*****************************************************************/ | |
68 | static const uint32_t crc32Table[256] = { | |
69 | 0x00000000L, 0xF26B8303L, 0xE13B70F7L, 0x1350F3F4L, | |
70 | 0xC79A971FL, 0x35F1141CL, 0x26A1E7E8L, 0xD4CA64EBL, | |
71 | 0x8AD958CFL, 0x78B2DBCCL, 0x6BE22838L, 0x9989AB3BL, | |
72 | 0x4D43CFD0L, 0xBF284CD3L, 0xAC78BF27L, 0x5E133C24L, | |
73 | 0x105EC76FL, 0xE235446CL, 0xF165B798L, 0x030E349BL, | |
74 | 0xD7C45070L, 0x25AFD373L, 0x36FF2087L, 0xC494A384L, | |
75 | 0x9A879FA0L, 0x68EC1CA3L, 0x7BBCEF57L, 0x89D76C54L, | |
76 | 0x5D1D08BFL, 0xAF768BBCL, 0xBC267848L, 0x4E4DFB4BL, | |
77 | 0x20BD8EDEL, 0xD2D60DDDL, 0xC186FE29L, 0x33ED7D2AL, | |
78 | 0xE72719C1L, 0x154C9AC2L, 0x061C6936L, 0xF477EA35L, | |
79 | 0xAA64D611L, 0x580F5512L, 0x4B5FA6E6L, 0xB93425E5L, | |
80 | 0x6DFE410EL, 0x9F95C20DL, 0x8CC531F9L, 0x7EAEB2FAL, | |
81 | 0x30E349B1L, 0xC288CAB2L, 0xD1D83946L, 0x23B3BA45L, | |
82 | 0xF779DEAEL, 0x05125DADL, 0x1642AE59L, 0xE4292D5AL, | |
83 | 0xBA3A117EL, 0x4851927DL, 0x5B016189L, 0xA96AE28AL, | |
84 | 0x7DA08661L, 0x8FCB0562L, 0x9C9BF696L, 0x6EF07595L, | |
85 | 0x417B1DBCL, 0xB3109EBFL, 0xA0406D4BL, 0x522BEE48L, | |
86 | 0x86E18AA3L, 0x748A09A0L, 0x67DAFA54L, 0x95B17957L, | |
87 | 0xCBA24573L, 0x39C9C670L, 0x2A993584L, 0xD8F2B687L, | |
88 | 0x0C38D26CL, 0xFE53516FL, 0xED03A29BL, 0x1F682198L, | |
89 | 0x5125DAD3L, 0xA34E59D0L, 0xB01EAA24L, 0x42752927L, | |
90 | 0x96BF4DCCL, 0x64D4CECFL, 0x77843D3BL, 0x85EFBE38L, | |
91 | 0xDBFC821CL, 0x2997011FL, 0x3AC7F2EBL, 0xC8AC71E8L, | |
92 | 0x1C661503L, 0xEE0D9600L, 0xFD5D65F4L, 0x0F36E6F7L, | |
93 | 0x61C69362L, 0x93AD1061L, 0x80FDE395L, 0x72966096L, | |
94 | 0xA65C047DL, 0x5437877EL, 0x4767748AL, 0xB50CF789L, | |
95 | 0xEB1FCBADL, 0x197448AEL, 0x0A24BB5AL, 0xF84F3859L, | |
96 | 0x2C855CB2L, 0xDEEEDFB1L, 0xCDBE2C45L, 0x3FD5AF46L, | |
97 | 0x7198540DL, 0x83F3D70EL, 0x90A324FAL, 0x62C8A7F9L, | |
98 | 0xB602C312L, 0x44694011L, 0x5739B3E5L, 0xA55230E6L, | |
99 | 0xFB410CC2L, 0x092A8FC1L, 0x1A7A7C35L, 0xE811FF36L, | |
100 | 0x3CDB9BDDL, 0xCEB018DEL, 0xDDE0EB2AL, 0x2F8B6829L, | |
101 | 0x82F63B78L, 0x709DB87BL, 0x63CD4B8FL, 0x91A6C88CL, | |
102 | 0x456CAC67L, 0xB7072F64L, 0xA457DC90L, 0x563C5F93L, | |
103 | 0x082F63B7L, 0xFA44E0B4L, 0xE9141340L, 0x1B7F9043L, | |
104 | 0xCFB5F4A8L, 0x3DDE77ABL, 0x2E8E845FL, 0xDCE5075CL, | |
105 | 0x92A8FC17L, 0x60C37F14L, 0x73938CE0L, 0x81F80FE3L, | |
106 | 0x55326B08L, 0xA759E80BL, 0xB4091BFFL, 0x466298FCL, | |
107 | 0x1871A4D8L, 0xEA1A27DBL, 0xF94AD42FL, 0x0B21572CL, | |
108 | 0xDFEB33C7L, 0x2D80B0C4L, 0x3ED04330L, 0xCCBBC033L, | |
109 | 0xA24BB5A6L, 0x502036A5L, 0x4370C551L, 0xB11B4652L, | |
110 | 0x65D122B9L, 0x97BAA1BAL, 0x84EA524EL, 0x7681D14DL, | |
111 | 0x2892ED69L, 0xDAF96E6AL, 0xC9A99D9EL, 0x3BC21E9DL, | |
112 | 0xEF087A76L, 0x1D63F975L, 0x0E330A81L, 0xFC588982L, | |
113 | 0xB21572C9L, 0x407EF1CAL, 0x532E023EL, 0xA145813DL, | |
114 | 0x758FE5D6L, 0x87E466D5L, 0x94B49521L, 0x66DF1622L, | |
115 | 0x38CC2A06L, 0xCAA7A905L, 0xD9F75AF1L, 0x2B9CD9F2L, | |
116 | 0xFF56BD19L, 0x0D3D3E1AL, 0x1E6DCDEEL, 0xEC064EEDL, | |
117 | 0xC38D26C4L, 0x31E6A5C7L, 0x22B65633L, 0xD0DDD530L, | |
118 | 0x0417B1DBL, 0xF67C32D8L, 0xE52CC12CL, 0x1747422FL, | |
119 | 0x49547E0BL, 0xBB3FFD08L, 0xA86F0EFCL, 0x5A048DFFL, | |
120 | 0x8ECEE914L, 0x7CA56A17L, 0x6FF599E3L, 0x9D9E1AE0L, | |
121 | 0xD3D3E1ABL, 0x21B862A8L, 0x32E8915CL, 0xC083125FL, | |
122 | 0x144976B4L, 0xE622F5B7L, 0xF5720643L, 0x07198540L, | |
123 | 0x590AB964L, 0xAB613A67L, 0xB831C993L, 0x4A5A4A90L, | |
124 | 0x9E902E7BL, 0x6CFBAD78L, 0x7FAB5E8CL, 0x8DC0DD8FL, | |
125 | 0xE330A81AL, 0x115B2B19L, 0x020BD8EDL, 0xF0605BEEL, | |
126 | 0x24AA3F05L, 0xD6C1BC06L, 0xC5914FF2L, 0x37FACCF1L, | |
127 | 0x69E9F0D5L, 0x9B8273D6L, 0x88D28022L, 0x7AB90321L, | |
128 | 0xAE7367CAL, 0x5C18E4C9L, 0x4F48173DL, 0xBD23943EL, | |
129 | 0xF36E6F75L, 0x0105EC76L, 0x12551F82L, 0xE03E9C81L, | |
130 | 0x34F4F86AL, 0xC69F7B69L, 0xD5CF889DL, 0x27A40B9EL, | |
131 | 0x79B737BAL, 0x8BDCB4B9L, 0x988C474DL, 0x6AE7C44EL, | |
132 | 0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L | |
133 | }; | |
134 | ||
135 | /* | |
136 | * Compute a CRC32c checksum as per the SCTP requirements in RFC4960. This | |
137 | * includes beginning with a checksum of all ones, and returning the negated | |
138 | * CRC. Unlike the RFC, we return the checksum in network byte-order. | |
139 | */ | |
140 | ovs_be32 | |
141 | crc32c(const uint8_t *data, size_t size) | |
142 | { | |
143 | uint32_t crc = 0xffffffffL; | |
144 | ||
145 | while (size--) { | |
146 | crc = crc32Table[(crc ^ *data++) & 0xff] ^ (crc >> 8); | |
147 | } | |
148 | ||
149 | /* The result of this CRC calculation provides us a value in the reverse | |
150 | * byte-order as compared with our architecture. On big-endian systems, | |
151 | * this is opposite to our return type. So, to return a big-endian | |
152 | * value, we must swap the byte-order. */ | |
153 | #if defined(WORDS_BIGENDIAN) | |
154 | crc = uint32_byteswap(crc); | |
155 | #endif | |
156 | ||
157 | /* Our value is in network byte-order. OVS_FORCE keeps sparse happy. */ | |
158 | return (OVS_FORCE ovs_be32) ~crc; | |
159 | } |