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   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2
   3 /* Copyright (C) 2009-2021 Free Software Foundation, Inc. */
   4
   5 /* Copied from https://github.com/gcc-mirror/gcc/blob/master/libiberty/crc32.c
   6  * and then tweaked a little. */
   7
   8 /* This table was generated by the following program.
   9    #include <stdio.h>
  10    int
  11    main ()
  12    {
  13      unsigned int i, j;
  14      unsigned int c;
  15      int table[256];
  16      for (i = 0; i < 256; i++)
  17        {
  18          for (c = i << 24, j = 8; j > 0; --j)
  19            c = c & 0x80000000 ? (c << 1) ^ 0x04c11db7 : (c << 1);
  20          table[i] = c;
  21        }
  22      printf ("static const unsigned int crc32_table[] =\n{\n");
  23      for (i = 0; i < 256; i += 4)
  24        {
  25          printf ("  0x%08x, 0x%08x, 0x%08x, 0x%08x",
  26                  table[i + 0], table[i + 1], table[i + 2], table[i + 3]);
  27          if (i + 4 < 256)
  28            putchar (',');
  29          putchar ('\n');
  30        }
  31      printf ("};\n");
  32      return 0;
  33    }
  34    For more information on CRC, see, e.g.,
  35    http://www.ross.net/crc/download/crc_v3.txt.  */
  36
  37 static const unsigned int crc32_table[] = {
  38         0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9,
  39         0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
  40         0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
  41         0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
  42         0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9,
  43         0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
  44         0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,
  45         0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
  46         0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
  47         0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
  48         0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81,
  49         0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
  50         0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
  51         0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
  52         0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
  53         0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
  54         0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,
  55         0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
  56         0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
  57         0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
  58         0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
  59         0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
  60         0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
  61         0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
  62         0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e,
  63         0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
  64         0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
  65         0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
  66         0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
  67         0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
  68         0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686,
  69         0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
  70         0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
  71         0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
  72         0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f,
  73         0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
  74         0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,
  75         0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
  76         0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
  77         0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
  78         0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7,
  79         0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
  80         0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
  81         0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
  82         0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
  83         0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
  84         0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,
  85         0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
  86         0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
  87         0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
  88         0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
  89         0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
  90         0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
  91         0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
  92         0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088,
  93         0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
  94         0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
  95         0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
  96         0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
  97         0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
  98         0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0,
  99         0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
 100         0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
 101         0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
 102 };
 103
 104 /*
 105 @deftypefn Extension {unsigned int} crc32 (const unsigned char *@var{buf}, @
 106   int @var{len}, unsigned int @var{init})
 107 Compute the 32-bit CRC of @var{buf} which has length @var{len}.  The
 108 starting value is 0xffffffff.
 109 This is used by the @command{gdb} remote protocol for the @samp{qCRC}
 110 command.
 111 This CRC can be specified as:
 112   Width  : 32
 113   Poly   : 0x04c11db7
 114   Init   : 0xffffffff
 115   RefIn  : false
 116   RefOut : false
 117   XorOut : 0
 118 This differs from the "standard" CRC-32 algorithm in that the values
 119 are not reflected, and there is no final XOR value.  These differences
 120 make it easy to compose the values of multiple blocks.
 121 @end deftypefn
 122 */
 123
 124 #include <stdint.h>
 125
 126 unsigned int
 127 xcrc32(const unsigned char *buf, int len)
 128 {
 129         uint32_t crc = 0xffffffff;
 130         while (len--) {
 131                 crc = (crc << 8) ^ crc32_table[((crc >> 24) ^ *buf) & 255];
 132                 buf++;
 133         }
 134         asm("mv a0, %0;"
 135                         "ebreak;"
 136                         :
 137                         : "r"(crc));
 138         return crc;
 139 }