mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-09-09 15:19:27 +02:00
973e9fb294
This only produces warnings under -Wcast-qual, but it's more correct and consistent in any case.
153 lines
4.4 KiB
C
153 lines
4.4 KiB
C
/*
|
|
* pg_crc.h
|
|
*
|
|
* PostgreSQL CRC support
|
|
*
|
|
* See Ross Williams' excellent introduction
|
|
* A PAINLESS GUIDE TO CRC ERROR DETECTION ALGORITHMS, available from
|
|
* http://www.ross.net/crc/ or several other net sites.
|
|
*
|
|
* We use a normal (not "reflected", in Williams' terms) CRC, using initial
|
|
* all-ones register contents and a final bit inversion.
|
|
*
|
|
* The 64-bit variant is not used as of PostgreSQL 8.1, but we retain the
|
|
* code for possible future use.
|
|
*
|
|
*
|
|
* Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
* src/include/utils/pg_crc.h
|
|
*/
|
|
#ifndef PG_CRC_H
|
|
#define PG_CRC_H
|
|
|
|
/* ugly hack to let this be used in frontend and backend code on Cygwin */
|
|
#ifdef FRONTEND
|
|
#define CRCDLLIMPORT
|
|
#else
|
|
#define CRCDLLIMPORT PGDLLIMPORT
|
|
#endif
|
|
|
|
typedef uint32 pg_crc32;
|
|
|
|
/* Initialize a CRC accumulator */
|
|
#define INIT_CRC32(crc) ((crc) = 0xFFFFFFFF)
|
|
|
|
/* Finish a CRC calculation */
|
|
#define FIN_CRC32(crc) ((crc) ^= 0xFFFFFFFF)
|
|
|
|
/* Accumulate some (more) bytes into a CRC */
|
|
#define COMP_CRC32(crc, data, len) \
|
|
do { \
|
|
const unsigned char *__data = (const unsigned char *) (data); \
|
|
uint32 __len = (len); \
|
|
\
|
|
while (__len-- > 0) \
|
|
{ \
|
|
int __tab_index = ((int) ((crc) >> 24) ^ *__data++) & 0xFF; \
|
|
(crc) = pg_crc32_table[__tab_index] ^ ((crc) << 8); \
|
|
} \
|
|
} while (0)
|
|
|
|
/* Check for equality of two CRCs */
|
|
#define EQ_CRC32(c1,c2) ((c1) == (c2))
|
|
|
|
/* Constant table for CRC calculation */
|
|
extern CRCDLLIMPORT const uint32 pg_crc32_table[];
|
|
|
|
|
|
#ifdef PROVIDE_64BIT_CRC
|
|
|
|
/*
|
|
* If we use a 64-bit integer type, then a 64-bit CRC looks just like the
|
|
* usual sort of implementation. However, we can also fake it with two
|
|
* 32-bit registers. Experience has shown that the two-32-bit-registers code
|
|
* is as fast as, or even much faster than, the 64-bit code on all but true
|
|
* 64-bit machines. We use SIZEOF_VOID_P to check the native word width.
|
|
*/
|
|
|
|
#if SIZEOF_VOID_P < 8
|
|
|
|
/*
|
|
* crc0 represents the LSBs of the 64-bit value, crc1 the MSBs. Note that
|
|
* with crc0 placed first, the output of 32-bit and 64-bit implementations
|
|
* will be bit-compatible only on little-endian architectures. If it were
|
|
* important to make the two possible implementations bit-compatible on
|
|
* all machines, we could do a configure test to decide how to order the
|
|
* two fields, but it seems not worth the trouble.
|
|
*/
|
|
typedef struct pg_crc64
|
|
{
|
|
uint32 crc0;
|
|
uint32 crc1;
|
|
} pg_crc64;
|
|
|
|
/* Initialize a CRC accumulator */
|
|
#define INIT_CRC64(crc) ((crc).crc0 = 0xffffffff, (crc).crc1 = 0xffffffff)
|
|
|
|
/* Finish a CRC calculation */
|
|
#define FIN_CRC64(crc) ((crc).crc0 ^= 0xffffffff, (crc).crc1 ^= 0xffffffff)
|
|
|
|
/* Accumulate some (more) bytes into a CRC */
|
|
#define COMP_CRC64(crc, data, len) \
|
|
do { \
|
|
uint32 __crc0 = (crc).crc0; \
|
|
uint32 __crc1 = (crc).crc1; \
|
|
unsigned char *__data = (unsigned char *) (data); \
|
|
uint32 __len = (len); \
|
|
\
|
|
while (__len-- > 0) \
|
|
{ \
|
|
int __tab_index = ((int) (__crc1 >> 24) ^ *__data++) & 0xFF; \
|
|
__crc1 = pg_crc64_table1[__tab_index] ^ ((__crc1 << 8) | (__crc0 >> 24)); \
|
|
__crc0 = pg_crc64_table0[__tab_index] ^ (__crc0 << 8); \
|
|
} \
|
|
(crc).crc0 = __crc0; \
|
|
(crc).crc1 = __crc1; \
|
|
} while (0)
|
|
|
|
/* Check for equality of two CRCs */
|
|
#define EQ_CRC64(c1,c2) ((c1).crc0 == (c2).crc0 && (c1).crc1 == (c2).crc1)
|
|
|
|
/* Constant table for CRC calculation */
|
|
extern CRCDLLIMPORT const uint32 pg_crc64_table0[];
|
|
extern CRCDLLIMPORT const uint32 pg_crc64_table1[];
|
|
#else /* use int64 implementation */
|
|
|
|
typedef struct pg_crc64
|
|
{
|
|
uint64 crc0;
|
|
} pg_crc64;
|
|
|
|
/* Initialize a CRC accumulator */
|
|
#define INIT_CRC64(crc) ((crc).crc0 = UINT64CONST(0xffffffffffffffff))
|
|
|
|
/* Finish a CRC calculation */
|
|
#define FIN_CRC64(crc) ((crc).crc0 ^= UINT64CONST(0xffffffffffffffff))
|
|
|
|
/* Accumulate some (more) bytes into a CRC */
|
|
#define COMP_CRC64(crc, data, len) \
|
|
do { \
|
|
uint64 __crc0 = (crc).crc0; \
|
|
unsigned char *__data = (unsigned char *) (data); \
|
|
uint32 __len = (len); \
|
|
\
|
|
while (__len-- > 0) \
|
|
{ \
|
|
int __tab_index = ((int) (__crc0 >> 56) ^ *__data++) & 0xFF; \
|
|
__crc0 = pg_crc64_table[__tab_index] ^ (__crc0 << 8); \
|
|
} \
|
|
(crc).crc0 = __crc0; \
|
|
} while (0)
|
|
|
|
/* Check for equality of two CRCs */
|
|
#define EQ_CRC64(c1,c2) ((c1).crc0 == (c2).crc0)
|
|
|
|
/* Constant table for CRC calculation */
|
|
extern CRCDLLIMPORT const uint64 pg_crc64_table[];
|
|
#endif /* SIZEOF_VOID_P < 8 */
|
|
#endif /* PROVIDE_64BIT_CRC */
|
|
|
|
#endif /* PG_CRC_H */
|