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code.delx.au - refind/blob - filesystems/crc32c.c
2 * this file take from grub 2.0
3 * for btrfs UEFI driver
6 * GRUB -- GRand Unified Bootloader
7 * Copyright (C) 2008 Free Software Foundation, Inc.
9 * GRUB is free software: you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation, either version 3 of the License, or
12 * (at your option) any later version.
14 * GRUB is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
23 static uint32_t crc32c_table
[256];
26 init_crc32c_table (void)
28 auto uint32_t reflect (uint32_t ref
, int len
);
29 uint32_t reflect (uint32_t ref
, int len
)
34 for (i
= 1; i
<= len
; i
++)
37 result
|= 1 << (len
- i
);
44 static int crc32c_table_inited
;
45 if(crc32c_table_inited
)
47 crc32c_table_inited
= 1;
49 uint32_t polynomial
= 0x1edc6f41;
52 for(i
= 0; i
< 256; i
++)
54 crc32c_table
[i
] = reflect(i
, 8) << 24;
55 for (j
= 0; j
< 8; j
++)
56 crc32c_table
[i
] = (crc32c_table
[i
] << 1) ^
57 (crc32c_table
[i
] & (1 << 31) ? polynomial
: 0);
58 crc32c_table
[i
] = reflect(crc32c_table
[i
], 32);
63 grub_getcrc32c (uint32_t crc
, const void *buf
, int size
)
66 const uint8_t *data
= buf
;
68 if (! crc32c_table
[1])
73 for (i
= 0; i
< size
; i
++)
75 crc
= (crc
>> 8) ^ crc32c_table
[(crc
& 0xFF) ^ *data
];
79 return crc
^ 0xffffffff;