70 lines
3.1 KiB
C
70 lines
3.1 KiB
C
// //////////////////////////////////////////////////////////
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// Crc32.h
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// Copyright (c) 2011-2019 Stephan Brumme. All rights reserved.
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// Slicing-by-16 contributed by Bulat Ziganshin
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// Tableless bytewise CRC contributed by Hagai Gold
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// see http://create.stephan-brumme.com/disclaimer.html
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//
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// if running on an embedded system, you might consider shrinking the
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// big Crc32Lookup table by undefining these lines:
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#define CRC32_USE_LOOKUP_TABLE_BYTE
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#define CRC32_USE_LOOKUP_TABLE_SLICING_BY_4
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#define CRC32_USE_LOOKUP_TABLE_SLICING_BY_8
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#define CRC32_USE_LOOKUP_TABLE_SLICING_BY_16
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// - crc32_bitwise doesn't need it at all
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// - crc32_halfbyte has its own small lookup table
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// - crc32_1byte_tableless and crc32_1byte_tableless2 don't need it at all
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// - crc32_1byte needs only Crc32Lookup[0]
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// - crc32_4bytes needs only Crc32Lookup[0..3]
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// - crc32_8bytes needs only Crc32Lookup[0..7]
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// - crc32_4x8bytes needs only Crc32Lookup[0..7]
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// - crc32_16bytes needs all of Crc32Lookup
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// using the aforementioned #defines the table is automatically fitted to your needs
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// uint8_t, uint32_t, int32_t
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#include <stdint.h>
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// size_t
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#include <cstddef>
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// crc32_fast selects the fastest algorithm depending on flags (CRC32_USE_LOOKUP_...)
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/// compute CRC32 using the fastest algorithm for large datasets on modern CPUs
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uint32_t crc32_fast (const void* data, size_t length, uint32_t previousCrc32 = 0);
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/// merge two CRC32 such that result = crc32(dataB, lengthB, crc32(dataA, lengthA))
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uint32_t crc32_combine (uint32_t crcA, uint32_t crcB, size_t lengthB);
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/// compute CRC32 (bitwise algorithm)
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uint32_t crc32_bitwise (const void* data, size_t length, uint32_t previousCrc32 = 0);
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/// compute CRC32 (half-byte algoritm)
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uint32_t crc32_halfbyte(const void* data, size_t length, uint32_t previousCrc32 = 0);
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#ifdef CRC32_USE_LOOKUP_TABLE_BYTE
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/// compute CRC32 (standard algorithm)
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uint32_t crc32_1byte (const void* data, size_t length, uint32_t previousCrc32 = 0);
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#endif
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/// compute CRC32 (byte algorithm) without lookup tables
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uint32_t crc32_1byte_tableless (const void* data, size_t length, uint32_t previousCrc32 = 0);
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/// compute CRC32 (byte algorithm) without lookup tables
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uint32_t crc32_1byte_tableless2(const void* data, size_t length, uint32_t previousCrc32 = 0);
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#ifdef CRC32_USE_LOOKUP_TABLE_SLICING_BY_4
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/// compute CRC32 (Slicing-by-4 algorithm)
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uint32_t crc32_4bytes (const void* data, size_t length, uint32_t previousCrc32 = 0);
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#endif
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#ifdef CRC32_USE_LOOKUP_TABLE_SLICING_BY_8
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/// compute CRC32 (Slicing-by-8 algorithm)
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uint32_t crc32_8bytes (const void* data, size_t length, uint32_t previousCrc32 = 0);
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/// compute CRC32 (Slicing-by-8 algorithm), unroll inner loop 4 times
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uint32_t crc32_4x8bytes(const void* data, size_t length, uint32_t previousCrc32 = 0);
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#endif
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#ifdef CRC32_USE_LOOKUP_TABLE_SLICING_BY_16
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/// compute CRC32 (Slicing-by-16 algorithm)
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uint32_t crc32_16bytes (const void* data, size_t length, uint32_t previousCrc32 = 0);
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/// compute CRC32 (Slicing-by-16 algorithm, prefetch upcoming data blocks)
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uint32_t crc32_16bytes_prefetch(const void* data, size_t length, uint32_t previousCrc32 = 0, size_t prefetchAhead = 256);
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#endif
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