65 lines
2.6 KiB
C
65 lines
2.6 KiB
C
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/*
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* rabin_polynomial_constants.h
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*
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* Created by Joel Lawrence Tucci on 09-May-2011.
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*
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* Copyright (c) 2011 Joel Lawrence Tucci
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* Neither the name of the project's author nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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//List of constants, mostly constraints and defaults for various parameters
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//to the Rabin Fingerprinting algorithm
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#define RAB_POLYNOMIAL_CONST 2
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// 1 << RAB_POLYNOMIAL_AVG_BLOCK_SHIFT = Average Rabin Chunk Size
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// So we are always looking at power of 2 chunk sizes to avoid doing a modulus
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//
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// A value of 11 below gives block size of 2048 bytes
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//
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#define RAB_POLYNOMIAL_AVG_BLOCK_SHIFT 11
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#define RAB_POLYNOMIAL_AVG_BLOCK_SIZE (1 << RAB_POLYNOMIAL_AVG_BLOCK_SHIFT)
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#define RAB_POLYNOMIAL_AVG_BLOCK_MASK (RAB_POLYNOMIAL_AVG_BLOCK_SIZE - 1)
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#define RAB_POLYNOMIAL_WIN_SIZE 32
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#define RAB_POLYNOMIAL_MIN_WIN_SIZE 17
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#define RAB_POLYNOMIAL_MAX_WIN_SIZE 63
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typedef struct {
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unsigned char *current_window_data;
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int window_pos;
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uint64_t cur_roll_checksum;
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} rabin_context_t;
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extern rabin_context_t *create_rabin_context();
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extern void destroy_rabin_context(rabin_context_t *ctx);
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extern ssize_t scan_rabin_chunks(rabin_context_t *ctx, void *buf,
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ssize_t size, ssize_t offset);
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