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) 1996-2020, 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 */ 102