1  /*
       2   * This code is from freebsd/sys/libkern/crc32.c
       3   *
       4   * Simplest table-based crc32c.  Performance is not important
       5   * for checking crcs on superblocks
       6   */
       7  
       8  /*-
       9   *  COPYRIGHT (C) 1986 Gary S. Brown.  You may use this program, or
      10   *  code or tables extracted from it, as desired without restriction.
      11   */
      12  
      13  #include <assert.h>
      14  #include "crc32c.h"
      15  
      16  static const uint32_t crc32Table[256] = {
      17  	0x00000000L, 0xF26B8303L, 0xE13B70F7L, 0x1350F3F4L,
      18  	0xC79A971FL, 0x35F1141CL, 0x26A1E7E8L, 0xD4CA64EBL,
      19  	0x8AD958CFL, 0x78B2DBCCL, 0x6BE22838L, 0x9989AB3BL,
      20  	0x4D43CFD0L, 0xBF284CD3L, 0xAC78BF27L, 0x5E133C24L,
      21  	0x105EC76FL, 0xE235446CL, 0xF165B798L, 0x030E349BL,
      22  	0xD7C45070L, 0x25AFD373L, 0x36FF2087L, 0xC494A384L,
      23  	0x9A879FA0L, 0x68EC1CA3L, 0x7BBCEF57L, 0x89D76C54L,
      24  	0x5D1D08BFL, 0xAF768BBCL, 0xBC267848L, 0x4E4DFB4BL,
      25  	0x20BD8EDEL, 0xD2D60DDDL, 0xC186FE29L, 0x33ED7D2AL,
      26  	0xE72719C1L, 0x154C9AC2L, 0x061C6936L, 0xF477EA35L,
      27  	0xAA64D611L, 0x580F5512L, 0x4B5FA6E6L, 0xB93425E5L,
      28  	0x6DFE410EL, 0x9F95C20DL, 0x8CC531F9L, 0x7EAEB2FAL,
      29  	0x30E349B1L, 0xC288CAB2L, 0xD1D83946L, 0x23B3BA45L,
      30  	0xF779DEAEL, 0x05125DADL, 0x1642AE59L, 0xE4292D5AL,
      31  	0xBA3A117EL, 0x4851927DL, 0x5B016189L, 0xA96AE28AL,
      32  	0x7DA08661L, 0x8FCB0562L, 0x9C9BF696L, 0x6EF07595L,
      33  	0x417B1DBCL, 0xB3109EBFL, 0xA0406D4BL, 0x522BEE48L,
      34  	0x86E18AA3L, 0x748A09A0L, 0x67DAFA54L, 0x95B17957L,
      35  	0xCBA24573L, 0x39C9C670L, 0x2A993584L, 0xD8F2B687L,
      36  	0x0C38D26CL, 0xFE53516FL, 0xED03A29BL, 0x1F682198L,
      37  	0x5125DAD3L, 0xA34E59D0L, 0xB01EAA24L, 0x42752927L,
      38  	0x96BF4DCCL, 0x64D4CECFL, 0x77843D3BL, 0x85EFBE38L,
      39  	0xDBFC821CL, 0x2997011FL, 0x3AC7F2EBL, 0xC8AC71E8L,
      40  	0x1C661503L, 0xEE0D9600L, 0xFD5D65F4L, 0x0F36E6F7L,
      41  	0x61C69362L, 0x93AD1061L, 0x80FDE395L, 0x72966096L,
      42  	0xA65C047DL, 0x5437877EL, 0x4767748AL, 0xB50CF789L,
      43  	0xEB1FCBADL, 0x197448AEL, 0x0A24BB5AL, 0xF84F3859L,
      44  	0x2C855CB2L, 0xDEEEDFB1L, 0xCDBE2C45L, 0x3FD5AF46L,
      45  	0x7198540DL, 0x83F3D70EL, 0x90A324FAL, 0x62C8A7F9L,
      46  	0xB602C312L, 0x44694011L, 0x5739B3E5L, 0xA55230E6L,
      47  	0xFB410CC2L, 0x092A8FC1L, 0x1A7A7C35L, 0xE811FF36L,
      48  	0x3CDB9BDDL, 0xCEB018DEL, 0xDDE0EB2AL, 0x2F8B6829L,
      49  	0x82F63B78L, 0x709DB87BL, 0x63CD4B8FL, 0x91A6C88CL,
      50  	0x456CAC67L, 0xB7072F64L, 0xA457DC90L, 0x563C5F93L,
      51  	0x082F63B7L, 0xFA44E0B4L, 0xE9141340L, 0x1B7F9043L,
      52  	0xCFB5F4A8L, 0x3DDE77ABL, 0x2E8E845FL, 0xDCE5075CL,
      53  	0x92A8FC17L, 0x60C37F14L, 0x73938CE0L, 0x81F80FE3L,
      54  	0x55326B08L, 0xA759E80BL, 0xB4091BFFL, 0x466298FCL,
      55  	0x1871A4D8L, 0xEA1A27DBL, 0xF94AD42FL, 0x0B21572CL,
      56  	0xDFEB33C7L, 0x2D80B0C4L, 0x3ED04330L, 0xCCBBC033L,
      57  	0xA24BB5A6L, 0x502036A5L, 0x4370C551L, 0xB11B4652L,
      58  	0x65D122B9L, 0x97BAA1BAL, 0x84EA524EL, 0x7681D14DL,
      59  	0x2892ED69L, 0xDAF96E6AL, 0xC9A99D9EL, 0x3BC21E9DL,
      60  	0xEF087A76L, 0x1D63F975L, 0x0E330A81L, 0xFC588982L,
      61  	0xB21572C9L, 0x407EF1CAL, 0x532E023EL, 0xA145813DL,
      62  	0x758FE5D6L, 0x87E466D5L, 0x94B49521L, 0x66DF1622L,
      63  	0x38CC2A06L, 0xCAA7A905L, 0xD9F75AF1L, 0x2B9CD9F2L,
      64  	0xFF56BD19L, 0x0D3D3E1AL, 0x1E6DCDEEL, 0xEC064EEDL,
      65  	0xC38D26C4L, 0x31E6A5C7L, 0x22B65633L, 0xD0DDD530L,
      66  	0x0417B1DBL, 0xF67C32D8L, 0xE52CC12CL, 0x1747422FL,
      67  	0x49547E0BL, 0xBB3FFD08L, 0xA86F0EFCL, 0x5A048DFFL,
      68  	0x8ECEE914L, 0x7CA56A17L, 0x6FF599E3L, 0x9D9E1AE0L,
      69  	0xD3D3E1ABL, 0x21B862A8L, 0x32E8915CL, 0xC083125FL,
      70  	0x144976B4L, 0xE622F5B7L, 0xF5720643L, 0x07198540L,
      71  	0x590AB964L, 0xAB613A67L, 0xB831C993L, 0x4A5A4A90L,
      72  	0x9E902E7BL, 0x6CFBAD78L, 0x7FAB5E8CL, 0x8DC0DD8FL,
      73  	0xE330A81AL, 0x115B2B19L, 0x020BD8EDL, 0xF0605BEEL,
      74  	0x24AA3F05L, 0xD6C1BC06L, 0xC5914FF2L, 0x37FACCF1L,
      75  	0x69E9F0D5L, 0x9B8273D6L, 0x88D28022L, 0x7AB90321L,
      76  	0xAE7367CAL, 0x5C18E4C9L, 0x4F48173DL, 0xBD23943EL,
      77  	0xF36E6F75L, 0x0105EC76L, 0x12551F82L, 0xE03E9C81L,
      78  	0x34F4F86AL, 0xC69F7B69L, 0xD5CF889DL, 0x27A40B9EL,
      79  	0x79B737BAL, 0x8BDCB4B9L, 0x988C474DL, 0x6AE7C44EL,
      80  	0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L
      81  };
      82  
      83  /*
      84   *This was singletable_crc32c() in bsd
      85   *
      86   * If you will not be passing crc back into this function to process more bytes,
      87   * the answer is:
      88   *
      89   *    crc = crc32c(~0L, buf, size);
      90   *  [ crc = crc32c(crc, buf, size); ]
      91   *    crc ^= ~0L
      92   *
      93   */
      94  uint32_t
      95  crc32c(uint32_t crc, const void *buf, size_t size)
      96  {
      97  	const uint8_t *p = buf;
      98  
      99  	while (size--)
     100  		crc = crc32Table[(crc ^ *p++) & 0xff] ^ (crc >> 8);
     101  
     102  	return crc;
     103  }
     104  
     105  uint32_t
     106  ul_crc32c_exclude_offset(uint32_t crc, const unsigned char *buf, size_t size,
     107  			 size_t exclude_off, size_t exclude_len)
     108  {
     109  	size_t i;
     110  
     111  	assert((exclude_off + exclude_len) <= size);
     112  
     113  	crc = crc32c(crc, buf, exclude_off);
     114  	for (i = 0; i < exclude_len; i++) {
     115  		uint8_t zero = 0;
     116  		crc = crc32c(crc, &zero, 1);
     117  	}
     118  	crc = crc32c(crc, &buf[exclude_off + exclude_len],
     119  		     size - (exclude_off + exclude_len));
     120  	return crc;
     121  }