diff options
Diffstat (limited to 'src/include/common/pg_crc.h')
| -rw-r--r-- | src/include/common/pg_crc.h | 53 |
1 files changed, 37 insertions, 16 deletions
diff --git a/src/include/common/pg_crc.h b/src/include/common/pg_crc.h index ea03dbf8403..f496659baf1 100644 --- a/src/include/common/pg_crc.h +++ b/src/include/common/pg_crc.h @@ -41,19 +41,38 @@ typedef uint32 pg_crc32; +#ifdef HAVE__BUILTIN_BSWAP32 +#define BSWAP32(x) __builtin_bswap32(x) +#else +#define BSWAP32(x) (((x << 24) & 0xff000000) | \ + ((x << 8) & 0x00ff0000) | \ + ((x >> 8) & 0x0000ff00) | \ + ((x >> 24) & 0x000000ff)) +#endif + /* * CRC calculation using the CRC-32C (Castagnoli) polynomial. * * We use all-ones as the initial register contents and final bit inversion. * This is the same algorithm used e.g. in iSCSI. See RFC 3385 for more * details on the choice of polynomial. + * + * 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 INIT_CRC32C(crc) ((crc) = 0xFFFFFFFF) +#ifdef WORDS_BIGENDIAN +#define FIN_CRC32C(crc) ((crc) = BSWAP32(crc) ^ 0xFFFFFFFF) +#else #define FIN_CRC32C(crc) ((crc) ^= 0xFFFFFFFF) +#endif #define COMP_CRC32C(crc, data, len) \ - COMP_CRC32_NORMAL_TABLE(crc, data, len, pg_crc32c_table) + ((crc) = pg_comp_crc32c((crc), (data), (len))) #define EQ_CRC32C(c1, c2) ((c1) == (c2)) +extern pg_crc32 pg_comp_crc32c(pg_crc32 crc, const void *data, size_t len); + /* * CRC-32, the same used e.g. in Ethernet. * @@ -67,6 +86,19 @@ typedef uint32 pg_crc32; COMP_CRC32_NORMAL_TABLE(crc, data, len, pg_crc32_table) #define EQ_TRADITIONAL_CRC32(c1, c2) ((c1) == (c2)) +/* Sarwate's algorithm, for use with a "normal" lookup table */ +#define COMP_CRC32_NORMAL_TABLE(crc, data, len, table) \ +do { \ + const unsigned char *__data = (const unsigned char *) (data); \ + uint32 __len = (len); \ +\ + while (__len-- > 0) \ + { \ + int __tab_index = ((int) (crc) ^ *__data++) & 0xFF; \ + (crc) = table[__tab_index] ^ ((crc) >> 8); \ + } \ +} while (0) + /* * The CRC algorithm used for WAL et al in pre-9.5 versions. * @@ -88,20 +120,9 @@ typedef uint32 pg_crc32; #define EQ_LEGACY_CRC32(c1, c2) ((c1) == (c2)) /* - * Common code for CRC computation using a lookup table. + * Sarwate's algorithm, for use with a "reflected" lookup table (but in the + * legacy algorithm, we actually use it on a "normal" table, see above) */ -#define COMP_CRC32_NORMAL_TABLE(crc, data, len, table) \ -do { \ - const unsigned char *__data = (const unsigned char *) (data); \ - uint32 __len = (len); \ -\ - while (__len-- > 0) \ - { \ - int __tab_index = ((int) (crc) ^ *__data++) & 0xFF; \ - (crc) = table[__tab_index] ^ ((crc) >> 8); \ - } \ -} while (0) - #define COMP_CRC32_REFLECTED_TABLE(crc, data, len, table) \ do { \ const unsigned char *__data = (const unsigned char *) (data); \ @@ -115,7 +136,7 @@ do { \ } while (0) /* Constant tables for CRC-32C and CRC-32 polynomials */ -extern CRCDLLIMPORT const uint32 pg_crc32c_table[]; -extern CRCDLLIMPORT const uint32 pg_crc32_table[]; +extern CRCDLLIMPORT const uint32 pg_crc32c_table[8][256]; +extern CRCDLLIMPORT const uint32 pg_crc32_table[256]; #endif /* PG_CRC_H */ |