1 /*
2 * lfs util functions
3 *
4 * Copyright (c) 2017, Arm Limited. All rights reserved.
5 * SPDX-License-Identifier: BSD-3-Clause
6 */
7 #include "lfs_util.h"
8
9 // Only compile if user does not provide custom config
10 #ifndef LFS_CONFIG
11
12
13 // Software CRC implementation with small lookup table
lfs_crc(uint32_t crc,const void * buffer,size_t size)14 uint32_t lfs_crc(uint32_t crc, const void *buffer, size_t size) {
15 static const uint32_t rtable[16] = {
16 0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
17 0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
18 0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
19 0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c,
20 };
21
22 const uint8_t *data = buffer;
23
24 for (size_t i = 0; i < size; i++) {
25 crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 0)) & 0xf];
26 crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 4)) & 0xf];
27 }
28
29 return crc;
30 }
31
32
33 #endif
34