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/*-------------------------------------------------------------------------
*
* pg_crc32c.h
* Routines for computing CRC-32C checksums.
*
* The speed of CRC-32C calculation has a big impact on performance, so we
* jump through some hoops to get the best implementation for each
* platform. Some CPU architectures have special instructions for speeding
* up CRC calculations (e.g. Intel SSE 4.2), on other platforms we use the
* Slicing-by-8 algorithm which uses lookup tables.
*
* The public interface consists of four macros:
*
* INIT_CRC32C(crc)
* Initialize a CRC accumulator
*
* COMP_CRC32C(crc, data, len)
* Accumulate some (more) bytes into a CRC
*
* FIN_CRC32C(crc)
* Finish a CRC calculation
*
* EQ_CRC32C(c1, c2)
* Check for equality of two CRCs.
*
* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/port/pg_crc32c.h
*
*-------------------------------------------------------------------------
*/
#ifndef PG_CRC32C_H
#define PG_CRC32C_H
#include "port/pg_bswap.h"
typedef uint32 pg_crc32c;
/* The INIT and EQ macros are the same for all implementations. */
#define INIT_CRC32C(crc) ((crc) = 0xFFFFFFFF)
#define EQ_CRC32C(c1, c2) ((c1) == (c2))
#if defined(USE_SSE42_CRC32C)
/* Use SSE4.2 instructions. */
#define COMP_CRC32C(crc, data, len) \
((crc) = pg_comp_crc32c_sse42((crc), (data), (len)))
#define FIN_CRC32C(crc) ((crc) ^= 0xFFFFFFFF)
extern pg_crc32c pg_comp_crc32c_sse42(pg_crc32c crc, const void *data, size_t len);
#elif defined(USE_SSE42_CRC32C_WITH_RUNTIME_CHECK)
/*
* Use SSE4.2 instructions, but perform a runtime check first to check that
* they are available.
*/
#define COMP_CRC32C(crc, data, len) \
((crc) = pg_comp_crc32c((crc), (data), (len)))
#define FIN_CRC32C(crc) ((crc) ^= 0xFFFFFFFF)
extern pg_crc32c pg_comp_crc32c_sse42(pg_crc32c crc, const void *data, size_t len);
extern pg_crc32c pg_comp_crc32c_sb8(pg_crc32c crc, const void *data, size_t len);
extern pg_crc32c (*pg_comp_crc32c) (pg_crc32c crc, const void *data, size_t len);
#else
/*
* Use slicing-by-8 algorithm.
*
* On big-endian systems, the intermediate value is kept in reverse byte
* order, to avoid byte-swapping during the calculation. FIN_CRC32C reverses
* the bytes to the final order.
*/
#define COMP_CRC32C(crc, data, len) \
((crc) = pg_comp_crc32c_sb8((crc), (data), (len)))
#ifdef WORDS_BIGENDIAN
#define FIN_CRC32C(crc) ((crc) = BSWAP32(crc) ^ 0xFFFFFFFF)
#else
#define FIN_CRC32C(crc) ((crc) ^= 0xFFFFFFFF)
#endif
extern pg_crc32c pg_comp_crc32c_sb8(pg_crc32c crc, const void *data, size_t len);
#endif
#endif /* PG_CRC32C_H */
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