git.oblomov.eu Git - linux-2.6/blob - lib/libcrc32c.c

   1 /*
   2  * CRC32C
   3  *@Article{castagnoli-crc,
   4  * author =       { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
   5  * title =        {{Optimization of Cyclic Redundancy-Check Codes with 24
   6  *                 and 32 Parity Bits}},
   7  * journal =      IEEE Transactions on Communication,
   8  * year =         {1993},
   9  * volume =       {41},
  10  * number =       {6},
  11  * pages =        {},
  12  * month =        {June},
  13  *}
  14  * Used by the iSCSI driver, possibly others, and derived from the
  15  * the iscsi-crc.c module of the linux-iscsi driver at
  16  * http://linux-iscsi.sourceforge.net.
  17  *
  18  * Following the example of lib/crc32, this function is intended to be
  19  * flexible and useful for all users.  Modules that currently have their
  20  * own crc32c, but hopefully may be able to use this one are:
  21  *  net/sctp (please add all your doco to here if you change to
  22  *            use this one!)
  23  *  <endoflist>
  24  *
  25  * Copyright (c) 2004 Cisco Systems, Inc.
  26  *
  27  * This program is free software; you can redistribute it and/or modify it
  28  * under the terms of the GNU General Public License as published by the Free
  29  * Software Foundation; either version 2 of the License, or (at your option)
  30  * any later version.
  31  *
  32  */
  33 #include <linux/crc32c.h>
  34 #include <linux/compiler.h>
  35 #include <linux/module.h>
  36 #include <asm/byteorder.h>
  37
  38 MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
  39 MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations");
  40 MODULE_LICENSE("GPL");
  41
  42 #define CRC32C_POLY_BE 0x1EDC6F41
  43 #define CRC32C_POLY_LE 0x82F63B78
  44
  45 #ifndef CRC_LE_BITS
  46 # define CRC_LE_BITS 8
  47 #endif
  48
  49
  50 /*
  51  * Haven't generated a big-endian table yet, but the bit-wise version
  52  * should at least work.
  53  */
  54 #if defined CRC_BE_BITS && CRC_BE_BITS != 1
  55 #undef CRC_BE_BITS
  56 #endif
  57 #ifndef CRC_BE_BITS
  58 # define CRC_BE_BITS 1
  59 #endif
  60
  61 EXPORT_SYMBOL(crc32c_le);
  62
  63 #if CRC_LE_BITS == 1
  64 /*
  65  * Compute things bit-wise, as done in crc32.c.  We could share the tight
  66  * loop below with crc32 and vary the POLY if we don't find value in terms
  67  * of space and maintainability in keeping the two modules separate.
  68  */
  69 u32 __attribute_pure__
  70 crc32c_le(u32 crc, unsigned char const *p, size_t len)
  71 {
  72         int i;
  73         while (len--) {
  74                 crc ^= *p++;
  75                 for (i = 0; i < 8; i++)
  76                         crc = (crc >> 1) ^ ((crc & 1) ? CRC32C_POLY_LE : 0);
  77         }
  78         return crc;
  79 }
  80 #else
  81
  82 /*
  83  * This is the CRC-32C table
  84  * Generated with:
  85  * width = 32 bits
  86  * poly = 0x1EDC6F41
  87  * reflect input bytes = true
  88  * reflect output bytes = true
  89  */
  90
  91 static const u32 crc32c_table[256] = {
  92         0x00000000L, 0xF26B8303L, 0xE13B70F7L, 0x1350F3F4L,
  93         0xC79A971FL, 0x35F1141CL, 0x26A1E7E8L, 0xD4CA64EBL,
  94         0x8AD958CFL, 0x78B2DBCCL, 0x6BE22838L, 0x9989AB3BL,
  95         0x4D43CFD0L, 0xBF284CD3L, 0xAC78BF27L, 0x5E133C24L,
  96         0x105EC76FL, 0xE235446CL, 0xF165B798L, 0x030E349BL,
  97         0xD7C45070L, 0x25AFD373L, 0x36FF2087L, 0xC494A384L,
  98         0x9A879FA0L, 0x68EC1CA3L, 0x7BBCEF57L, 0x89D76C54L,
  99         0x5D1D08BFL, 0xAF768BBCL, 0xBC267848L, 0x4E4DFB4BL,
 100         0x20BD8EDEL, 0xD2D60DDDL, 0xC186FE29L, 0x33ED7D2AL,
 101         0xE72719C1L, 0x154C9AC2L, 0x061C6936L, 0xF477EA35L,
 102         0xAA64D611L, 0x580F5512L, 0x4B5FA6E6L, 0xB93425E5L,
 103         0x6DFE410EL, 0x9F95C20DL, 0x8CC531F9L, 0x7EAEB2FAL,
 104         0x30E349B1L, 0xC288CAB2L, 0xD1D83946L, 0x23B3BA45L,
 105         0xF779DEAEL, 0x05125DADL, 0x1642AE59L, 0xE4292D5AL,
 106         0xBA3A117EL, 0x4851927DL, 0x5B016189L, 0xA96AE28AL,
 107         0x7DA08661L, 0x8FCB0562L, 0x9C9BF696L, 0x6EF07595L,
 108         0x417B1DBCL, 0xB3109EBFL, 0xA0406D4BL, 0x522BEE48L,
 109         0x86E18AA3L, 0x748A09A0L, 0x67DAFA54L, 0x95B17957L,
 110         0xCBA24573L, 0x39C9C670L, 0x2A993584L, 0xD8F2B687L,
 111         0x0C38D26CL, 0xFE53516FL, 0xED03A29BL, 0x1F682198L,
 112         0x5125DAD3L, 0xA34E59D0L, 0xB01EAA24L, 0x42752927L,
 113         0x96BF4DCCL, 0x64D4CECFL, 0x77843D3BL, 0x85EFBE38L,
 114         0xDBFC821CL, 0x2997011FL, 0x3AC7F2EBL, 0xC8AC71E8L,
 115         0x1C661503L, 0xEE0D9600L, 0xFD5D65F4L, 0x0F36E6F7L,
 116         0x61C69362L, 0x93AD1061L, 0x80FDE395L, 0x72966096L,
 117         0xA65C047DL, 0x5437877EL, 0x4767748AL, 0xB50CF789L,
 118         0xEB1FCBADL, 0x197448AEL, 0x0A24BB5AL, 0xF84F3859L,
 119         0x2C855CB2L, 0xDEEEDFB1L, 0xCDBE2C45L, 0x3FD5AF46L,
 120         0x7198540DL, 0x83F3D70EL, 0x90A324FAL, 0x62C8A7F9L,
 121         0xB602C312L, 0x44694011L, 0x5739B3E5L, 0xA55230E6L,
 122         0xFB410CC2L, 0x092A8FC1L, 0x1A7A7C35L, 0xE811FF36L,
 123         0x3CDB9BDDL, 0xCEB018DEL, 0xDDE0EB2AL, 0x2F8B6829L,
 124         0x82F63B78L, 0x709DB87BL, 0x63CD4B8FL, 0x91A6C88CL,
 125         0x456CAC67L, 0xB7072F64L, 0xA457DC90L, 0x563C5F93L,
 126         0x082F63B7L, 0xFA44E0B4L, 0xE9141340L, 0x1B7F9043L,
 127         0xCFB5F4A8L, 0x3DDE77ABL, 0x2E8E845FL, 0xDCE5075CL,
 128         0x92A8FC17L, 0x60C37F14L, 0x73938CE0L, 0x81F80FE3L,
 129         0x55326B08L, 0xA759E80BL, 0xB4091BFFL, 0x466298FCL,
 130         0x1871A4D8L, 0xEA1A27DBL, 0xF94AD42FL, 0x0B21572CL,
 131         0xDFEB33C7L, 0x2D80B0C4L, 0x3ED04330L, 0xCCBBC033L,
 132         0xA24BB5A6L, 0x502036A5L, 0x4370C551L, 0xB11B4652L,
 133         0x65D122B9L, 0x97BAA1BAL, 0x84EA524EL, 0x7681D14DL,
 134         0x2892ED69L, 0xDAF96E6AL, 0xC9A99D9EL, 0x3BC21E9DL,
 135         0xEF087A76L, 0x1D63F975L, 0x0E330A81L, 0xFC588982L,
 136         0xB21572C9L, 0x407EF1CAL, 0x532E023EL, 0xA145813DL,
 137         0x758FE5D6L, 0x87E466D5L, 0x94B49521L, 0x66DF1622L,
 138         0x38CC2A06L, 0xCAA7A905L, 0xD9F75AF1L, 0x2B9CD9F2L,
 139         0xFF56BD19L, 0x0D3D3E1AL, 0x1E6DCDEEL, 0xEC064EEDL,
 140         0xC38D26C4L, 0x31E6A5C7L, 0x22B65633L, 0xD0DDD530L,
 141         0x0417B1DBL, 0xF67C32D8L, 0xE52CC12CL, 0x1747422FL,
 142         0x49547E0BL, 0xBB3FFD08L, 0xA86F0EFCL, 0x5A048DFFL,
 143         0x8ECEE914L, 0x7CA56A17L, 0x6FF599E3L, 0x9D9E1AE0L,
 144         0xD3D3E1ABL, 0x21B862A8L, 0x32E8915CL, 0xC083125FL,
 145         0x144976B4L, 0xE622F5B7L, 0xF5720643L, 0x07198540L,
 146         0x590AB964L, 0xAB613A67L, 0xB831C993L, 0x4A5A4A90L,
 147         0x9E902E7BL, 0x6CFBAD78L, 0x7FAB5E8CL, 0x8DC0DD8FL,
 148         0xE330A81AL, 0x115B2B19L, 0x020BD8EDL, 0xF0605BEEL,
 149         0x24AA3F05L, 0xD6C1BC06L, 0xC5914FF2L, 0x37FACCF1L,
 150         0x69E9F0D5L, 0x9B8273D6L, 0x88D28022L, 0x7AB90321L,
 151         0xAE7367CAL, 0x5C18E4C9L, 0x4F48173DL, 0xBD23943EL,
 152         0xF36E6F75L, 0x0105EC76L, 0x12551F82L, 0xE03E9C81L,
 153         0x34F4F86AL, 0xC69F7B69L, 0xD5CF889DL, 0x27A40B9EL,
 154         0x79B737BAL, 0x8BDCB4B9L, 0x988C474DL, 0x6AE7C44EL,
 155         0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L
 156 };
 157
 158 /*
 159  * Steps through buffer one byte at at time, calculates reflected
 160  * crc using table.
 161  */
 162
 163 u32 __attribute_pure__
 164 crc32c_le(u32 seed, unsigned char const *data, size_t length)
 165 {
 166         u32 crc = __cpu_to_le32(seed);
 167
 168         while (length--)
 169                 crc =
 170                     crc32c_table[(crc ^ *data++) & 0xFFL] ^ (crc >> 8);
 171
 172         return __le32_to_cpu(crc);
 173 }
 174
 175 #endif  /* CRC_LE_BITS == 8 */
 176
 177 EXPORT_SYMBOL(crc32c_be);
 178
 179 #if CRC_BE_BITS == 1
 180 u32 __attribute_pure__
 181 crc32c_be(u32 crc, unsigned char const *p, size_t len)
 182 {
 183         int i;
 184         while (len--) {
 185                 crc ^= *p++ << 24;
 186                 for (i = 0; i < 8; i++)
 187                         crc =
 188                             (crc << 1) ^ ((crc & 0x80000000) ? CRC32C_POLY_BE :
 189                                           0);
 190         }
 191         return crc;
 192 }
 193 #endif
 194
 195 /*
 196  * Unit test
 197  *
 198  * A small unit test suite is implemented as part of the crypto suite.
 199  * Select CRYPTO_CRC32C and use the tcrypt module to run the tests.
 200  */