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/* crc32.c

   Copyright (C) 2009 Free Software Foundation, Inc.

   This file is part of the libiberty library.

   This file is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 2 of the License, or

   (at your option) any later version.

   In addition to the permissions in the GNU General Public License, the

   Free Software Foundation gives you unlimited permission to link the

   compiled version of this file into combinations with other programs,

   and to distribute those combinations without any restriction coming

   from the use of this file.  (The General Public License restrictions

   do apply in other respects; for example, they cover modification of

   the file, and distribution when not linked into a combined

   executable.)

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program; if not, write to the Free Software

   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.

*/

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include "libiberty.h"

/* This table was generated by the following program.  This matches

   what gdb does.

   #include <stdio.h>

   int

   main ()

   {

     int i, j;

     unsigned int c;

     int table[256];

     for (i = 0; i < 256; i++)

       {

         for (c = i << 24, j = 8; j > 0; --j)

           c = c & 0x80000000 ? (c << 1) ^ 0x04c11db7 : (c << 1);

         table[i] = c;

       }

     printf ("static const unsigned int crc32_table[] =\n{\n");

     for (i = 0; i < 256; i += 4)

       {

         printf ("  0x%08x, 0x%08x, 0x%08x, 0x%08x",

                 table[i + 0], table[i + 1], table[i + 2], table[i + 3]);

         if (i + 4 < 256)

           putchar (',');

         putchar ('\n');

       }

     printf ("};\n");

     return 0;

   }

   For more information on CRC, see, e.g.,

   http://www.ross.net/crc/download/crc_v3.txt.  */

static const unsigned int crc32_table[] =

{

  0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9,

  0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,

  0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,

  0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,

  0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9,

  0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,

  0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,

  0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,

  0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,

  0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,

  0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81,

  0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,

  0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,

  0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,

  0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,

  0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,

  0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,

  0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,

  0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,

  0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,

  0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,

  0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,

  0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,

  0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,

  0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e,

  0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,

  0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,

  0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,

  0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,

  0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,

  0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686,

  0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,

  0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,

  0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,

  0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f,

  0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,

  0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,

  0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,

  0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,

  0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,

  0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7,

  0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,

  0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,

  0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,

  0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,

  0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,

  0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,

  0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,

  0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,

  0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,

  0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,

  0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,

  0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,

  0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,

  0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088,

  0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,

  0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,

  0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,

  0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,

  0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,

  0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0,

  0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,

  0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,

  0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4

};

/*

@deftypefn Extension unsigned int crc32 (const unsigned char *@var{buf}, int @var{len}, unsigned int @var{init})

Compute the 32-bit CRC of @var{buf} which has length @var{len}.  The

starting value is @var{init}; this may be used to compute the CRC of

data split across multiple buffers by passing the return value of each

call as the @var{init} parameter of the next.

This is intended to match the CRC used by the @command{gdb} remote

protocol for the @samp{qCRC} command.  In order to get the same

results as gdb for a block of data, you must pass the first CRC

parameter as @code{0xffffffff}.

This CRC can be specified as:

  Width  : 32

  Poly   : 0x04c11db7

  Init   : parameter, typically 0xffffffff

  RefIn  : false

  RefOut : false

  XorOut : 0

This differs from the "standard" CRC-32 algorithm in that the values

are not reflected, and there is no final XOR value.  These differences

make it easy to compose the values of multiple blocks.

@end deftypefn

*/

unsigned int

xcrc32 (const unsigned char *buf, int len, unsigned int init)

{

  unsigned int crc = init;

  while (len--)

    {

      crc = (crc << 8) ^ crc32_table[((crc >> 24) ^ *buf) & 255];

      buf++;

    }

  return crc;

}