51 lines
1.1 KiB
C
51 lines
1.1 KiB
C
/*
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* Copied from Linux kernel crypto/crc32c.c
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* Copyright (c) 2004 Cisco Systems, Inc.
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* Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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/*
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* This is the CRC-32C table
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* Generated with:
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* width = 32 bits
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* poly = 0x1EDC6F41
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* reflect input bytes = true
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* reflect output bytes = true
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*/
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static u32 crc32c_table[256];
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/*
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* Steps through buffer one byte at at time, calculates reflected
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* crc using table.
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*/
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static inline u32 crc32c_le(u32 crc, const char *data, size_t length)
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{
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while (length--)
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crc = crc32c_table[(u8)(crc ^ *data++)] ^ (crc >> 8);
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return crc;
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}
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static inline void btrfs_init_crc32c(void)
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{
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int i, j;
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u32 v;
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const u32 poly = 0x82F63B78; /* Bit-reflected CRC32C polynomial */
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for (i = 0; i < 256; i++) {
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v = i;
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for (j = 0; j < 8; j++) {
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v = (v >> 1) ^ ((v & 1) ? poly : 0);
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}
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crc32c_table[i] = v;
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}
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}
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