Crc32.hxx

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// //////////////////////////////////////////////////////////
// Crc32.h
// Copyright (c) 2011-2019 Stephan Brumme. All rights reserved.
// Slicing-by-16 contributed by Bulat Ziganshin
// Tableless bytewise CRC contributed by Hagai Gold
// see http://create.stephan-brumme.com/disclaimer.html
//
 
/* from LICENSE in the repository:
 
zlib License
 
Copyright (c) 2011-2016 Stephan Brumme
 
This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software.
   If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
 
*/
 
// if running on an embedded system, you might consider shrinking the
// big Crc32Lookup table by undefining these lines:
#define CRC32_USE_LOOKUP_TABLE_BYTE
#define CRC32_USE_LOOKUP_TABLE_SLICING_BY_4
#define CRC32_USE_LOOKUP_TABLE_SLICING_BY_8
#define CRC32_USE_LOOKUP_TABLE_SLICING_BY_16
// - crc32_bitwise  doesn't need it at all
// - crc32_halfbyte has its own small lookup table
// - crc32_1byte_tableless and crc32_1byte_tableless2 don't need it at all
// - crc32_1byte    needs only Crc32Lookup[0]
// - crc32_4bytes   needs only Crc32Lookup[0..3]
// - crc32_8bytes   needs only Crc32Lookup[0..7]
// - crc32_4x8bytes needs only Crc32Lookup[0..7]
// - crc32_16bytes  needs all of Crc32Lookup
// using the aforementioned #defines the table is automatically fitted to your needs
 
// uint8_t, uint32_t, int32_t
#include <stdint.h>
// size_t
#include <cstddef>
 
// crc32_fast selects the fastest algorithm depending on flags (CRC32_USE_LOOKUP_...)
uint32_t crc32_fast    (const void* data, size_t length, uint32_t previousCrc32 = 0);
 
uint32_t crc32_combine (uint32_t crcA, uint32_t crcB, size_t lengthB);
 
uint32_t crc32_bitwise (const void* data, size_t length, uint32_t previousCrc32 = 0);
uint32_t crc32_halfbyte(const void* data, size_t length, uint32_t previousCrc32 = 0);
 
#ifdef CRC32_USE_LOOKUP_TABLE_BYTE
uint32_t crc32_1byte   (const void* data, size_t length, uint32_t previousCrc32 = 0);
#endif
 
uint32_t crc32_1byte_tableless (const void* data, size_t length, uint32_t previousCrc32 = 0);
uint32_t crc32_1byte_tableless2(const void* data, size_t length, uint32_t previousCrc32 = 0);
 
#ifdef CRC32_USE_LOOKUP_TABLE_SLICING_BY_4
uint32_t crc32_4bytes  (const void* data, size_t length, uint32_t previousCrc32 = 0);
#endif
 
#ifdef CRC32_USE_LOOKUP_TABLE_SLICING_BY_8
uint32_t crc32_8bytes  (const void* data, size_t length, uint32_t previousCrc32 = 0);
uint32_t crc32_4x8bytes(const void* data, size_t length, uint32_t previousCrc32 = 0);
#endif
 
#ifdef CRC32_USE_LOOKUP_TABLE_SLICING_BY_16
uint32_t crc32_16bytes (const void* data, size_t length, uint32_t previousCrc32 = 0);
uint32_t crc32_16bytes_prefetch(const void* data, size_t length, uint32_t previousCrc32 = 0, size_t prefetchAhead = 256);
#endif