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https://github.com/littlefs-project/littlefs.git
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fe28ea0f93
Before, the littlefs relied on the underlying block device to report corruption that occurs when writing data to disk. This requirement is easy to miss or implement incorrectly, since the error detection is only required when a block becomes corrupted, which is very unlikely to happen until late in the block device's lifetime. The littlefs can detect corruption itself by reading back written data. This requires a bit of care to reuse the available buffers, and may rely on checksums to avoid additional RAM requirements. This does have a runtime penalty with the extra read operations, but should make the littlefs much more robust to different implementations.
26 lines
699 B
C
26 lines
699 B
C
/*
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* lfs util functions
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*
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* Copyright (c) 2017 Christopher Haster
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* Distributed under the MIT license
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*/
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#include "lfs_util.h"
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void lfs_crc(uint32_t *restrict 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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}
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