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9a620c730c
Now you can override littlefs's CRC implementation with some simple defines: -DLFS_CRC=lfs_crc The motivation for this is the same for LFS_MALLOC/LFS_FREE. I think these are the main "system-level" utils that users want to override. Don't override with this something that's not CRC32! Your filesystem will no longer be compatible with other tools! This is only intended for provided hardware acceleration!
38 lines
988 B
C
38 lines
988 B
C
/*
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* lfs util functions
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*
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* Copyright (c) 2022, The littlefs authors.
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* Copyright (c) 2017, Arm Limited. All rights reserved.
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include "lfs_util.h"
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// Only compile if user does not provide custom config
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#ifndef LFS_CONFIG
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// If user provides their own CRC impl we don't need this
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#ifndef LFS_CRC
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// Software CRC implementation with small lookup table
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uint32_t lfs_crc(uint32_t crc, const void *buffer, size_t size) {
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static const uint32_t rtable[16] = {
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0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
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0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
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0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
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0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c,
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};
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const uint8_t *data = buffer;
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for (size_t i = 0; i < size; i++) {
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crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 0)) & 0xf];
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crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 4)) & 0xf];
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}
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return crc;
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}
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#endif
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#endif
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