mirror of
https://gitee.com/beecue/fastbee.git
synced 2025-12-21 02:15:55 +08:00
60 lines
1.5 KiB
C
60 lines
1.5 KiB
C
/*
|
|
* lfs util functions
|
|
*
|
|
* Copyright (c) 2017, Arm Limited. All rights reserved.
|
|
* SPDX-License-Identifier: BSD-3-Clause
|
|
*/
|
|
#include "lfs_util.h"
|
|
|
|
// Only compile if user does not provide custom config
|
|
#ifndef LFS_CONFIG
|
|
|
|
|
|
// Software CRC implementation with small lookup table
|
|
uint32_t lfs_crc(uint32_t crc, const void *buffer, size_t size) {
|
|
static uint32_t rtable[16] = {
|
|
0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
|
|
0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
|
|
0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
|
|
0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c,
|
|
};
|
|
|
|
#if 0
|
|
const uint8_t *data = buffer;
|
|
|
|
for (size_t i = 0; i < size; i++) {
|
|
crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 0)) & 0xf];
|
|
crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 4)) & 0xf];
|
|
}
|
|
|
|
#else
|
|
|
|
uint32_t *data_32 = (uint32_t*)buffer;
|
|
|
|
for(size_t i = 0; i < (size >> 2); i++, data_32++)
|
|
{
|
|
uint32_t aWord = *data_32;
|
|
|
|
for(size_t j = 0; j < 4; j++)
|
|
{
|
|
crc = (crc >> 4) ^ rtable[(crc ^ ((aWord & 0xff) >> 0)) & 0xf];
|
|
crc = (crc >> 4) ^ rtable[(crc ^ ((aWord & 0xff) >> 4)) & 0xf];
|
|
aWord >>= 8;
|
|
}
|
|
|
|
}
|
|
const uint8_t* data_8 = (uint8_t*)data_32;
|
|
|
|
for (size_t i = 0; i < (size & 0x3); i++)
|
|
{
|
|
crc = (crc >> 4) ^ rtable[(crc ^ (data_8[i] >> 0)) & 0xf];
|
|
crc = (crc >> 4) ^ rtable[(crc ^ (data_8[i] >> 4)) & 0xf];
|
|
}
|
|
|
|
#endif
|
|
return crc;
|
|
}
|
|
|
|
|
|
#endif
|