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78 lines
2.2 KiB
78 lines
2.2 KiB
3 months ago
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/*
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* CRC32 (Castagnoli 1993)
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*
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* Based on Michael E. Kounavis and Frank L. Berry: A Systematic Approach
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* to Building High Performance Software-based CRC Generators
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* (Proceedings of the 10th IEEE Symposium on Computers and Communications 2005)
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*
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* Includes code from http://sourceforge.net/projects/slicing-by-8/,
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* which carried the following copyright notice:
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*
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* Copyright (c) 2004-2006 Intel Corporation - All Rights Reserved
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*
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* This software program is licensed subject to the BSD License,
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* available at http://www.opensource.org/licenses/bsd-license.html
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*
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* Adapted for LibUCW by Martin Mares <mj@ucw.cz> in 2012.
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*/
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#ifndef _UCW_CRC_H
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#define _UCW_CRC_H
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#ifdef CONFIG_UCW_CLEAN_ABI
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#define crc32_hash_buffer ucw_crc32_hash_buffer
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#define crc32_init ucw_crc32_init
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#endif
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/**
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* Internal CRC calculator context.
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* You should use it just as an opaque handle only.
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*/
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typedef struct crc32_context {
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u32 state;
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void (*update_func)(struct crc32_context *ctx, const byte *buf, uint len);
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} crc32_context;
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/**
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* Initialize new calculation of CRC in a given context.
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* @crc_mode selects which algorithm should be used.
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**/
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void crc32_init(crc32_context *ctx, uint crc_mode);
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/**
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* Algorithm used for CRC calculation. The algorithms differ by the amount
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* of precomputed tables they use. Bigger tables imply faster calculation
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* at the cost of an increased cache footprint.
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**/
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enum crc_mode {
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CRC_MODE_DEFAULT, /* Default algorithm (4K table) */
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CRC_MODE_SMALL, /* Optimize for small data (1K table) */
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CRC_MODE_BIG, /* Optimize for large data (8K table) */
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CRC_MODE_MAX,
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};
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/** Feed @len bytes starting at @buf to the CRC calculator. **/
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static inline void crc32_update(crc32_context *ctx, const byte *buf, uint len)
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{
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ctx->update_func(ctx, buf, len);
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}
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/** Finish calculation and return the CRC value. **/
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static inline u32 crc32_final(crc32_context *ctx)
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{
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return ctx->state ^ 0xffffffff;
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}
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/**
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* A convenience one-shot function for CRC.
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* It is equivalent to this snippet of code:
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*
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* crc32_context ctx;
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* crc32_init(&ctx, CRC_MODE_DEFAULT);
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* crc32_update(&ctx, buf, len);
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* return crc32_final(&ctx);
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*/
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u32 crc32_hash_buffer(const byte *buf, uint len);
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#endif
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