1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
|
/*
* pg_crc.h
*
* PostgreSQL 64-bit CRC support
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: pg_crc.h,v 1.3 2001/03/23 18:42:12 tgl Exp $
*/
#ifndef PG_CRC_H
#define PG_CRC_H
/*
* If we have a 64-bit integer type, then a 64-bit CRC looks just like the
* usual sort of implementation. (See Ross Williams' excellent introduction
* A PAINLESS GUIDE TO CRC ERROR DETECTION ALGORITHMS, available from
* ftp://ftp.rocksoft.com/papers/crc_v3.txt or several other net sites.)
* If we have no working 64-bit type, then fake it with two 32-bit registers.
*
* The present implementation is a normal (not "reflected", in Williams'
* terms) 64-bit CRC, using initial all-ones register contents and a final
* bit inversion. The chosen polynomial is borrowed from the DLT1 spec
* (ECMA-182, available from http://www.ecma.ch/ecma1/STAND/ECMA-182.HTM):
*
* x^64 + x^62 + x^57 + x^55 + x^54 + x^53 + x^52 + x^47 + x^46 + x^45 +
* x^40 + x^39 + x^38 + x^37 + x^35 + x^33 + x^32 + x^31 + x^29 + x^27 +
* x^24 + x^23 + x^22 + x^21 + x^19 + x^17 + x^13 + x^12 + x^10 + x^9 +
* x^7 + x^4 + x + 1
*/
#ifdef INT64_IS_BUSTED
/*
* 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 crc64
{
uint32 crc0;
uint32 crc1;
} 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 = crc_table1[__tab_index] ^ ((__crc1 << 8) | (__crc0 >> 24)); \
__crc0 = crc_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 const uint32 crc_table0[];
extern const uint32 crc_table1[];
#else /* int64 works */
/* decide if we need to decorate constants */
#ifdef HAVE_LL_CONSTANTS
#define INT64CONST(x) x##LL
#else
#define INT64CONST(x) x
#endif
typedef struct crc64
{
uint64 crc0;
} crc64;
/* Initialize a CRC accumulator */
#define INIT_CRC64(crc) ((crc).crc0 = INT64CONST(0xffffffffffffffff))
/* Finish a CRC calculation */
#define FIN_CRC64(crc) ((crc).crc0 ^= INT64CONST(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 = crc_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 const uint64 crc_table[];
#endif /* INT64_IS_BUSTED */
#endif /* PG_CRC_H */
|
