2
Copyright (c) 1990-1999 Info-ZIP. All rights reserved.
4
See the accompanying file LICENSE, version 1999-Oct-05 or later
5
(the contents of which are also included in zip.h) for terms of use.
6
If, for some reason, both of these files are missing, the Info-ZIP license
7
also may be found at: ftp://ftp.cdrom.com/pub/infozip/license.html
9
/* crctab.c -- supply the CRC table needed for CRC-32 calculations.
10
* Copyright (C) 1995 Mark Adler
11
* For conditions of distribution and use, see copyright notice in zlib.h
14
/* $Id: z_crctab.c 7481 2005-08-25 21:33:28Z davea $ */
17
Generate a table for a byte-wise 32-bit CRC calculation on the polynomial:
18
x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x+1.
20
Polynomials over GF(2) are represented in binary, one bit per coefficient,
21
with the lowest powers in the most significant bit. Then adding polynomials
22
is just exclusive-or, and multiplying a polynomial by x is a right shift by
23
one. If we call the above polynomial p, and represent a byte as the
24
polynomial q, also with the lowest power in the most significant bit (so the
25
byte 0xb1 is the polynomial x^7+x^3+x+1), then the CRC is (q*x^32) mod p,
26
where a mod b means the remainder after dividing a by b.
28
This calculation is done using the shift-register method of multiplying and
29
taking the remainder. The register is initialized to zero, and for each
30
incoming bit, x^32 is added mod p to the register if the bit is a one (where
31
x^32 mod p is p+x^32 = x^26+...+1), and the register is multiplied mod p by
32
x (which is shifting right by one and adding x^32 mod p if the bit shifted
33
out is a one). We start with the highest power (least significant bit) of
34
q and repeat for all eight bits of q.
36
The table is simply the CRC of all possible eight bit values. This is all
37
the information needed to generate CRC's on data a byte at a time for all
38
combinations of CRC register values and incoming bytes.
41
#define __CRCTAB_C /* identifies this source module */
45
#if (!defined(USE_ZLIB) || defined(USE_OWN_CRCTAB))
51
#ifdef DYNAMIC_CRC_TABLE
53
/* =========================================================================
54
* Make the crc table. This function is needed only if you want to compute
55
* the table dynamically.
58
local void make_crc_table OF((void));
60
#if (defined(DYNALLOC_CRCTAB) && defined(REENTRANT))
61
error: Dynamic allocation of CRC table not safe with reentrant code.
62
#endif /* DYNALLOC_CRCTAB && REENTRANT */
64
#ifdef DYNALLOC_CRCTAB
65
local ulg near *crc_table = NULL;
66
# if 0 /* not used, since sizeof("near *") <= sizeof(int) */
67
/* Use this section when access to a "local int" is faster than access to
68
a "local pointer" (e.g.: i86 16bit code with far pointers). */
69
local int crc_table_empty = 1;
70
# define CRC_TABLE_IS_EMPTY (crc_table_empty != 0)
71
# define MARK_CRCTAB_FILLED crc_table_empty = 0
72
# define MARK_CRCTAB_EMPTY crc_table_empty = 1
74
/* Use this section on systems where the size of pointers and ints is
75
equal (e.g.: all 32bit systems). */
76
# define CRC_TABLE_IS_EMPTY (crc_table == NULL)
77
# define MARK_CRCTAB_FILLED crc_table = crctab_p
78
# define MARK_CRCTAB_EMPTY crc_table = NULL
80
#else /* !DYNALLOC_CRCTAB */
81
local ulg near crc_table[256];
82
local int crc_table_empty = 1;
83
# define CRC_TABLE_IS_EMPTY (crc_table_empty != 0)
84
# define MARK_CRCTAB_FILLED crc_table_empty = 0
85
#endif /* ?DYNALLOC_CRCTAB */
88
local void make_crc_table()
90
ulg c; /* crc shift register */
91
int n; /* counter for all possible eight bit values */
92
int k; /* byte being shifted into crc apparatus */
93
#ifdef DYNALLOC_CRCTAB
94
ulg near *crctab_p; /* temporary pointer to allocated crc_table area */
95
#else /* !DYNALLOC_CRCTAB */
96
# define crctab_p crc_table
97
#endif /* DYNALLOC_CRCTAB */
99
#ifdef COMPUTE_XOR_PATTERN
100
/* This piece of code has been left here to explain how the XOR pattern
101
* used in the creation of the crc_table values can be recomputed.
102
* For production versions of this function, it is more efficient to
103
* supply the resultant pattern at compile time.
105
ulg xor; /* polynomial exclusive-or pattern */
106
/* terms of polynomial defining this crc (except x^32): */
107
static uch p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};
109
/* make exclusive-or pattern from polynomial (0xedb88320L) */
111
for (i = 0; i < sizeof(p)/sizeof(uch); i++)
112
xor |= 1L << (31 - p[i]);
114
# define xor 0xedb88320L
117
#ifdef DYNALLOC_CRCTAB
118
crctab_p = (ulg near *) nearmalloc (256*sizeof(ulg));
119
if (crctab_p == NULL) {
120
ziperr(ZE_MEM, "crc_table allocation");
122
#endif /* DYNALLOC_CRCTAB */
124
for (n = 0; n < 256; n++) {
127
c = c & 1 ? xor ^ (c >> 1) : c >> 1;
133
#else /* !DYNAMIC_CRC_TABLE */
135
#ifdef DYNALLOC_CRCTAB
136
error: Inconsistent flags, DYNALLOC_CRCTAB without DYNAMIC_CRC_TABLE.
139
/* ========================================================================
140
* Table of CRC-32's of all single-byte values (made by make_crc_table)
142
local ZCONST ulg near crc_table[256] = {
143
0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
144
0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
145
0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
146
0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
147
0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
148
0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
149
0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
150
0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
151
0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
152
0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
153
0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
154
0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
155
0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
156
0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
157
0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
158
0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
159
0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
160
0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
161
0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
162
0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
163
0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
164
0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
165
0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
166
0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
167
0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
168
0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
169
0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
170
0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
171
0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
172
0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
173
0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
174
0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
175
0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
176
0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
177
0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
178
0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
179
0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
180
0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
181
0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
182
0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
183
0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
184
0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
185
0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
186
0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
187
0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
188
0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
189
0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
190
0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
191
0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
192
0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
193
0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
196
#endif /* ?DYNAMIC_CRC_TABLE */
198
/* use "OF((void))" here to work around a Borland TC++ 1.0 problem */
200
ZCONST uLongf *get_crc_table_boinc OF((void))
202
ZCONST ulg near *get_crc_table_boinc OF((void))
205
#ifdef DYNAMIC_CRC_TABLE
206
if (CRC_TABLE_IS_EMPTY)
210
return (ZCONST uLongf *)crc_table;
212
return (ZCONST ulg near *)crc_table;
216
#ifdef DYNALLOC_CRCTAB
217
void free_crc_table()
219
if (!CRC_TABLE_IS_EMPTY)
221
nearfree((ulg near *)crc_table);
227
#endif /* !USE_ZLIB || USE_OWN_CRCTAB */
229
const char *BOINC_RCSID_7b30f2d851 = "$Id: z_crctab.c 7481 2005-08-25 21:33:28Z davea $";
added
removed
zip/zip/z_crctab.c
