src/include/port/pg_crc32c.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * pg_crc32c.h
   4  *        Routines for computing CRC-32C checksums.
   5  *
   6  * The speed of CRC-32C calculation has a big impact on performance, so we
   7  * jump through some hoops to get the best implementation for each
   8  * platform. Some CPU architectures have special instructions for speeding
   9  * up CRC calculations (e.g. Intel SSE 4.2), on other platforms we use the
  10  * Slicing-by-8 algorithm which uses lookup tables.
  11  *
  12  * The public interface consists of four macros:
  13  *
  14  * INIT_CRC32C(crc)
  15  *              Initialize a CRC accumulator
  16  *
  17  * COMP_CRC32C(crc, data, len)
  18  *              Accumulate some (more) bytes into a CRC
  19  *
  20  * FIN_CRC32C(crc)
  21  *              Finish a CRC calculation
  22  *
  23  * EQ_CRC32C(c1, c2)
  24  *              Check for equality of two CRCs.
  25  *
  26  * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
  27  * Portions Copyright (c) 1994, Regents of the University of California
  28  *
  29  * src/include/port/pg_crc32c.h
  30  *
  31  *-------------------------------------------------------------------------
  32  */
  33 #ifndef PG_CRC32C_H
  34 #define PG_CRC32C_H
  35
  36 #include "port/pg_bswap.h"
  37
  38 typedef uint32 pg_crc32c;
  39
  40 /* The INIT and EQ macros are the same for all implementations. */
  41 #define INIT_CRC32C(crc) ((crc) = 0xFFFFFFFF)
  42 #define EQ_CRC32C(c1, c2) ((c1) == (c2))
  43
  44 #if defined(USE_SSE42_CRC32C)
  45 /* Use Intel SSE4.2 instructions. */
  46 #define COMP_CRC32C(crc, data, len) \
  47         ((crc) = pg_comp_crc32c_sse42((crc), (data), (len)))
  48 #define FIN_CRC32C(crc) ((crc) ^= 0xFFFFFFFF)
  49
  50 extern pg_crc32c pg_comp_crc32c_sse42(pg_crc32c crc, const void *data, size_t len);
  51
  52 #elif defined(USE_ARMV8_CRC32C)
  53 /* Use ARMv8 CRC Extension instructions. */
  54
  55 #define COMP_CRC32C(crc, data, len)                                                     \
  56         ((crc) = pg_comp_crc32c_armv8((crc), (data), (len)))
  57 #define FIN_CRC32C(crc) ((crc) ^= 0xFFFFFFFF)
  58
  59 extern pg_crc32c pg_comp_crc32c_armv8(pg_crc32c crc, const void *data, size_t len);
  60
  61 #elif defined(USE_SSE42_CRC32C_WITH_RUNTIME_CHECK) || defined(USE_ARMV8_CRC32C_WITH_RUNTIME_CHECK)
  62
  63 /*
  64  * Use Intel SSE 4.2 or ARMv8 instructions, but perform a runtime check first
  65  * to check that they are available.
  66  */
  67 #define COMP_CRC32C(crc, data, len) \
  68         ((crc) = pg_comp_crc32c((crc), (data), (len)))
  69 #define FIN_CRC32C(crc) ((crc) ^= 0xFFFFFFFF)
  70
  71 extern pg_crc32c pg_comp_crc32c_sb8(pg_crc32c crc, const void *data, size_t len);
  72 extern pg_crc32c (*pg_comp_crc32c) (pg_crc32c crc, const void *data, size_t len);
  73
  74 #ifdef USE_SSE42_CRC32C_WITH_RUNTIME_CHECK
  75 extern pg_crc32c pg_comp_crc32c_sse42(pg_crc32c crc, const void *data, size_t len);
  76 #endif
  77 #ifdef USE_ARMV8_CRC32C_WITH_RUNTIME_CHECK
  78 extern pg_crc32c pg_comp_crc32c_armv8(pg_crc32c crc, const void *data, size_t len);
  79 #endif
  80
  81 #else
  82 /*
  83  * Use slicing-by-8 algorithm.
  84  *
  85  * On big-endian systems, the intermediate value is kept in reverse byte
  86  * order, to avoid byte-swapping during the calculation. FIN_CRC32C reverses
  87  * the bytes to the final order.
  88  */
  89 #define COMP_CRC32C(crc, data, len) \
  90         ((crc) = pg_comp_crc32c_sb8((crc), (data), (len)))
  91 #ifdef WORDS_BIGENDIAN
  92 #define FIN_CRC32C(crc) ((crc) = pg_bswap32(crc) ^ 0xFFFFFFFF)
  93 #else
  94 #define FIN_CRC32C(crc) ((crc) ^= 0xFFFFFFFF)
  95 #endif
  96
  97 extern pg_crc32c pg_comp_crc32c_sb8(pg_crc32c crc, const void *data, size_t len);
  98
  99 #endif
 100
 101 #endif                                                  /* PG_CRC32C_H */