linux/lib/libcrc32c.c
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   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
  37MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
  38MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations");
  39MODULE_LICENSE("GPL");
  40
  41#define CRC32C_POLY_BE 0x1EDC6F41
  42#define CRC32C_POLY_LE 0x82F63B78
  43
  44#ifndef CRC_LE_BITS 
  45# define CRC_LE_BITS 8
  46#endif
  47
  48
  49/*
  50 * Haven't generated a big-endian table yet, but the bit-wise version
  51 * should at least work.
  52 */
  53#if defined CRC_BE_BITS && CRC_BE_BITS != 1
  54#undef CRC_BE_BITS
  55#endif
  56#ifndef CRC_BE_BITS
  57# define CRC_BE_BITS 1
  58#endif
  59
  60EXPORT_SYMBOL(crc32c_le);
  61
  62#if CRC_LE_BITS == 1
  63/*
  64 * Compute things bit-wise, as done in crc32.c.  We could share the tight 
  65 * loop below with crc32 and vary the POLY if we don't find value in terms
  66 * of space and maintainability in keeping the two modules separate.
  67 */
  68u32 __pure
  69crc32c_le(u32 crc, unsigned char const *p, size_t len)
  70{
  71        int i;
  72        while (len--) {
  73                crc ^= *p++;
  74                for (i = 0; i < 8; i++)
  75                        crc = (crc >> 1) ^ ((crc & 1) ? CRC32C_POLY_LE : 0);
  76        }
  77        return crc;
  78}
  79#else
  80
  81/*
  82 * This is the CRC-32C table
  83 * Generated with:
  84 * width = 32 bits
  85 * poly = 0x1EDC6F41
  86 * reflect input bytes = true
  87 * reflect output bytes = true
  88 */
  89
  90static const u32 crc32c_table[256] = {
  91        0x00000000L, 0xF26B8303L, 0xE13B70F7L, 0x1350F3F4L,
  92        0xC79A971FL, 0x35F1141CL, 0x26A1E7E8L, 0xD4CA64EBL,
  93        0x8AD958CFL, 0x78B2DBCCL, 0x6BE22838L, 0x9989AB3BL,
  94        0x4D43CFD0L, 0xBF284CD3L, 0xAC78BF27L, 0x5E133C24L,
  95        0x105EC76FL, 0xE235446CL, 0xF165B798L, 0x030E349BL,
  96        0xD7C45070L, 0x25AFD373L, 0x36FF2087L, 0xC494A384L,
  97        0x9A879FA0L, 0x68EC1CA3L, 0x7BBCEF57L, 0x89D76C54L,
  98        0x5D1D08BFL, 0xAF768BBCL, 0xBC267848L, 0x4E4DFB4BL,
  99        0x20BD8EDEL, 0xD2D60DDDL, 0xC186FE29L, 0x33ED7D2AL,
 100        0xE72719C1L, 0x154C9AC2L, 0x061C6936L, 0xF477EA35L,
 101        0xAA64D611L, 0x580F5512L, 0x4B5FA6E6L, 0xB93425E5L,
 102        0x6DFE410EL, 0x9F95C20DL, 0x8CC531F9L, 0x7EAEB2FAL,
 103        0x30E349B1L, 0xC288CAB2L, 0xD1D83946L, 0x23B3BA45L,
 104        0xF779DEAEL, 0x05125DADL, 0x1642AE59L, 0xE4292D5AL,
 105        0xBA3A117EL, 0x4851927DL, 0x5B016189L, 0xA96AE28AL,
 106        0x7DA08661L, 0x8FCB0562L, 0x9C9BF696L, 0x6EF07595L,
 107        0x417B1DBCL, 0xB3109EBFL, 0xA0406D4BL, 0x522BEE48L,
 108        0x86E18AA3L, 0x748A09A0L, 0x67DAFA54L, 0x95B17957L,
 109        0xCBA24573L, 0x39C9C670L, 0x2A993584L, 0xD8F2B687L,
 110        0x0C38D26CL, 0xFE53516FL, 0xED03A29BL, 0x1F682198L,
 111        0x5125DAD3L, 0xA34E59D0L, 0xB01EAA24L, 0x42752927L,
 112        0x96BF4DCCL, 0x64D4CECFL, 0x77843D3BL, 0x85EFBE38L,
 113        0xDBFC821CL, 0x2997011FL, 0x3AC7F2EBL, 0xC8AC71E8L,
 114        0x1C661503L, 0xEE0D9600L, 0xFD5D65F4L, 0x0F36E6F7L,
 115        0x61C69362L, 0x93AD1061L, 0x80FDE395L, 0x72966096L,
 116        0xA65C047DL, 0x5437877EL, 0x4767748AL, 0xB50CF789L,
 117        0xEB1FCBADL, 0x197448AEL, 0x0A24BB5AL, 0xF84F3859L,
 118        0x2C855CB2L, 0xDEEEDFB1L, 0xCDBE2C45L, 0x3FD5AF46L,
 119        0x7198540DL, 0x83F3D70EL, 0x90A324FAL, 0x62C8A7F9L,
 120        0xB602C312L, 0x44694011L, 0x5739B3E5L, 0xA55230E6L,
 121        0xFB410CC2L, 0x092A8FC1L, 0x1A7A7C35L, 0xE811FF36L,
 122        0x3CDB9BDDL, 0xCEB018DEL, 0xDDE0EB2AL, 0x2F8B6829L,
 123        0x82F63B78L, 0x709DB87BL, 0x63CD4B8FL, 0x91A6C88CL,
 124        0x456CAC67L, 0xB7072F64L, 0xA457DC90L, 0x563C5F93L,
 125        0x082F63B7L, 0xFA44E0B4L, 0xE9141340L, 0x1B7F9043L,
 126        0xCFB5F4A8L, 0x3DDE77ABL, 0x2E8E845FL, 0xDCE5075CL,
 127        0x92A8FC17L, 0x60C37F14L, 0x73938CE0L, 0x81F80FE3L,
 128        0x55326B08L, 0xA759E80BL, 0xB4091BFFL, 0x466298FCL,
 129        0x1871A4D8L, 0xEA1A27DBL, 0xF94AD42FL, 0x0B21572CL,
 130        0xDFEB33C7L, 0x2D80B0C4L, 0x3ED04330L, 0xCCBBC033L,
 131        0xA24BB5A6L, 0x502036A5L, 0x4370C551L, 0xB11B4652L,
 132        0x65D122B9L, 0x97BAA1BAL, 0x84EA524EL, 0x7681D14DL,
 133        0x2892ED69L, 0xDAF96E6AL, 0xC9A99D9EL, 0x3BC21E9DL,
 134        0xEF087A76L, 0x1D63F975L, 0x0E330A81L, 0xFC588982L,
 135        0xB21572C9L, 0x407EF1CAL, 0x532E023EL, 0xA145813DL,
 136        0x758FE5D6L, 0x87E466D5L, 0x94B49521L, 0x66DF1622L,
 137        0x38CC2A06L, 0xCAA7A905L, 0xD9F75AF1L, 0x2B9CD9F2L,
 138        0xFF56BD19L, 0x0D3D3E1AL, 0x1E6DCDEEL, 0xEC064EEDL,
 139        0xC38D26C4L, 0x31E6A5C7L, 0x22B65633L, 0xD0DDD530L,
 140        0x0417B1DBL, 0xF67C32D8L, 0xE52CC12CL, 0x1747422FL,
 141        0x49547E0BL, 0xBB3FFD08L, 0xA86F0EFCL, 0x5A048DFFL,
 142        0x8ECEE914L, 0x7CA56A17L, 0x6FF599E3L, 0x9D9E1AE0L,
 143        0xD3D3E1ABL, 0x21B862A8L, 0x32E8915CL, 0xC083125FL,
 144        0x144976B4L, 0xE622F5B7L, 0xF5720643L, 0x07198540L,
 145        0x590AB964L, 0xAB613A67L, 0xB831C993L, 0x4A5A4A90L,
 146        0x9E902E7BL, 0x6CFBAD78L, 0x7FAB5E8CL, 0x8DC0DD8FL,
 147        0xE330A81AL, 0x115B2B19L, 0x020BD8EDL, 0xF0605BEEL,
 148        0x24AA3F05L, 0xD6C1BC06L, 0xC5914FF2L, 0x37FACCF1L,
 149        0x69E9F0D5L, 0x9B8273D6L, 0x88D28022L, 0x7AB90321L,
 150        0xAE7367CAL, 0x5C18E4C9L, 0x4F48173DL, 0xBD23943EL,
 151        0xF36E6F75L, 0x0105EC76L, 0x12551F82L, 0xE03E9C81L,
 152        0x34F4F86AL, 0xC69F7B69L, 0xD5CF889DL, 0x27A40B9EL,
 153        0x79B737BAL, 0x8BDCB4B9L, 0x988C474DL, 0x6AE7C44EL,
 154        0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L
 155};
 156
 157/*
 158 * Steps through buffer one byte at at time, calculates reflected 
 159 * crc using table.
 160 */
 161
 162u32 __pure
 163crc32c_le(u32 crc, unsigned char const *data, size_t length)
 164{
 165        while (length--)
 166                crc =
 167                    crc32c_table[(crc ^ *data++) & 0xFFL] ^ (crc >> 8);
 168
 169        return crc;
 170}
 171
 172#endif  /* CRC_LE_BITS == 8 */
 173
 174EXPORT_SYMBOL(crc32c_be);
 175
 176#if CRC_BE_BITS == 1
 177u32 __pure
 178crc32c_be(u32 crc, unsigned char const *p, size_t len)
 179{
 180        int i;
 181        while (len--) {
 182                crc ^= *p++ << 24;
 183                for (i = 0; i < 8; i++)
 184                        crc =
 185                            (crc << 1) ^ ((crc & 0x80000000) ? CRC32C_POLY_BE :
 186                                          0);
 187        }
 188        return crc;
 189}
 190#endif
 191
 192/*
 193 * Unit test
 194 *
 195 * A small unit test suite is implemented as part of the crypto suite.
 196 * Select CRYPTO_CRC32C and use the tcrypt module to run the tests.
 197 */
 198
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