mirror of
https://github.com/CloverHackyColor/CloverBootloader.git
synced 2024-12-21 15:57:42 +01:00
77 lines
1.8 KiB
C
77 lines
1.8 KiB
C
/* crc.c - crc function */
|
|
/*
|
|
* GRUB -- GRand Unified Bootloader
|
|
* Copyright (C) 2008 Free Software Foundation, Inc.
|
|
*
|
|
* GRUB 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 3 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* GRUB 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 GRUB. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include <grub/types.h>
|
|
#include <grub/lib/crc.h>
|
|
|
|
static grub_uint32_t crc32c_table [256];
|
|
|
|
/* Helper for init_crc32c_table. */
|
|
static grub_uint32_t
|
|
reflect (grub_uint32_t ref, int len)
|
|
{
|
|
grub_uint32_t result = 0;
|
|
int i;
|
|
|
|
for (i = 1; i <= len; i++)
|
|
{
|
|
if (ref & 1)
|
|
result |= 1 << (len - i);
|
|
ref >>= 1;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
static void
|
|
init_crc32c_table (void)
|
|
{
|
|
grub_uint32_t polynomial = 0x1edc6f41;
|
|
int i, j;
|
|
|
|
for(i = 0; i < 256; i++)
|
|
{
|
|
crc32c_table[i] = reflect(i, 8) << 24;
|
|
for (j = 0; j < 8; j++)
|
|
crc32c_table[i] = (crc32c_table[i] << 1) ^
|
|
(crc32c_table[i] & (1 << 31) ? polynomial : 0);
|
|
crc32c_table[i] = reflect(crc32c_table[i], 32);
|
|
}
|
|
}
|
|
|
|
grub_uint32_t
|
|
grub_getcrc32c (grub_uint32_t crc, const void *buf, int size)
|
|
{
|
|
int i;
|
|
const grub_uint8_t *data = buf;
|
|
|
|
if (! crc32c_table[1])
|
|
init_crc32c_table ();
|
|
|
|
crc^= 0xffffffff;
|
|
|
|
for (i = 0; i < size; i++)
|
|
{
|
|
crc = (crc >> 8) ^ crc32c_table[(crc & 0xFF) ^ *data];
|
|
data++;
|
|
}
|
|
|
|
return crc ^ 0xffffffff;
|
|
}
|