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31 lines
831 B
31 lines
831 B
/* |
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* lfs util functions |
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* |
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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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/* Use the LFS naive CRC implementation until it has been decided which CRC to |
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* use for LittleFS. |
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*/ |
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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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{ |
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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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