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authorMark Adler <madler@alumni.caltech.edu>2011-09-09 23:21:47 -0700
committerMark Adler <madler@alumni.caltech.edu>2011-09-09 23:21:47 -0700
commit7c2a874e50b871d04fbd19501f7b42cff55e5abc (patch)
tree1879cd29182ababb17cde77cee5ce74505db4006 /crc32.c
parenta383133c4e7b93113cee912f213cf9502d785fa7 (diff)
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zlib 1.2.0v1.2.0
Diffstat (limited to 'crc32.c')
-rw-r--r--crc32.c350
1 files changed, 248 insertions, 102 deletions
diff --git a/crc32.c b/crc32.c
index 60deca2..d0a9f5e 100644
--- a/crc32.c
+++ b/crc32.c
@@ -1,22 +1,68 @@
1/* crc32.c -- compute the CRC-32 of a data stream 1/* crc32.c -- compute the CRC-32 of a data stream
2 * Copyright (C) 1995-2002 Mark Adler 2 * Copyright (C) 1995-2003 Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h 3 * For conditions of distribution and use, see copyright notice in zlib.h
4 *
5 * Thanks to Rodney Brown <rbrown64@csc.com.au> for his contribution of faster
6 * CRC methods: exclusive-oring 32 bits of data at a time, and pre-computing
7 * tables for updating the shift register in one step with three exclusive-ors
8 * instead of four steps with four exclusive-ors. This results about a 50%
9 * increase in speed on a Power PC using gcc -O3.
4 */ 10 */
5 11
6/* @(#) $Id$ */ 12/* @(#) $Id$ */
7 13
14#ifdef MAKECRCH
15# include <stdio.h>
16# ifndef DYNAMIC_CRC_TABLE
17# define DYNAMIC_CRC_TABLE
18# endif /* !DYNAMIC_CRC_TABLE */
19#endif /* MAKECRCH */
20
8#include "zlib.h" 21#include "zlib.h"
9 22
10#define local static 23#define local static
11 24
25/* Find a four-byte integer type for crc32_little() and crc32_big(). */
26#ifndef NOBYFOUR
27# ifdef __STDC__ /* need ANSI C limits.h to determine sizes */
28# include <limits.h>
29# define BYFOUR
30# if (UINT_MAX == 4294967295)
31 typedef unsigned int u4;
32# elif (ULONG_MAX == 4294967295)
33 typedef unsigned long u4;
34# elif (USHRT_MAX == 4294967295)
35 typedef unsigned short u4;
36# else
37# undef BYFOUR /* can't find a four-byte integer type! */
38# endif
39# endif /* __STDC__ */
40#endif /* !NOBYFOUR */
41
42/* Definitions for doing the crc four data bytes at a time. */
43#ifdef BYFOUR
44# define REV(w) (((w)>>24)+(((w)>>8)&0xff00)+ \
45 (((w)&0xff00)<<8)+(((w)&0xff)<<24))
46 local unsigned long crc32_little OF((unsigned long,
47 const unsigned char FAR *, unsigned));
48 local unsigned long crc32_big OF((unsigned long,
49 const unsigned char FAR *, unsigned));
50# define TBLS 8
51#else
52# define TBLS 1
53#endif /* BYFOUR */
54
12#ifdef DYNAMIC_CRC_TABLE 55#ifdef DYNAMIC_CRC_TABLE
13 56
14local int crc_table_empty = 1; 57local int crc_table_empty = 1;
15local uLongf crc_table[256]; 58local unsigned long FAR crc_table[TBLS][256];
16local void make_crc_table OF((void)); 59local void make_crc_table OF((void));
60#ifdef MAKECRCH
61 local void write_table OF((FILE *, const unsigned long FAR *));
62#endif /* MAKECRCH */
17 63
18/* 64/*
19 Generate a table for a byte-wise 32-bit CRC calculation on the polynomial: 65 Generate tables for a byte-wise 32-bit CRC calculation on the polynomial:
20 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. 66 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.
21 67
22 Polynomials over GF(2) are represented in binary, one bit per coefficient, 68 Polynomials over GF(2) are represented in binary, one bit per coefficient,
@@ -35,128 +81,228 @@ local void make_crc_table OF((void));
35 out is a one). We start with the highest power (least significant bit) of 81 out is a one). We start with the highest power (least significant bit) of
36 q and repeat for all eight bits of q. 82 q and repeat for all eight bits of q.
37 83
38 The table is simply the CRC of all possible eight bit values. This is all 84 The first table is simply the CRC of all possible eight bit values. This is
39 the information needed to generate CRC's on data a byte at a time for all 85 all the information needed to generate CRCs on data a byte at a time for all
40 combinations of CRC register values and incoming bytes. 86 combinations of CRC register values and incoming bytes. The remaining tables
87 allow for word-at-a-time CRC calculation for both big-endian and little-
88 endian machines, where a word is four bytes.
41*/ 89*/
42local void make_crc_table() 90local void make_crc_table()
43{ 91{
44 uLong c; 92 unsigned long c;
45 int n, k; 93 int n, k;
46 uLong poly; /* polynomial exclusive-or pattern */ 94 unsigned long poly; /* polynomial exclusive-or pattern */
47 /* terms of polynomial defining this crc (except x^32): */ 95 /* terms of polynomial defining this crc (except x^32): */
48 static const Byte p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26}; 96 static const unsigned char p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};
49 97
50 /* make exclusive-or pattern from polynomial (0xedb88320L) */ 98 /* make exclusive-or pattern from polynomial (0xedb88320L) */
51 poly = 0L; 99 poly = 0UL;
52 for (n = 0; n < sizeof(p)/sizeof(Byte); n++) 100 for (n = 0; n < sizeof(p)/sizeof(unsigned char); n++)
53 poly |= 1L << (31 - p[n]); 101 poly |= 1UL << (31 - p[n]);
54 102
55 for (n = 0; n < 256; n++) 103 /* generate a crc for every 8-bit value */
56 { 104 for (n = 0; n < 256; n++) {
57 c = (uLong)n; 105 c = (unsigned long)n;
58 for (k = 0; k < 8; k++) 106 for (k = 0; k < 8; k++)
59 c = c & 1 ? poly ^ (c >> 1) : c >> 1; 107 c = c & 1 ? poly ^ (c >> 1) : c >> 1;
60 crc_table[n] = c; 108 crc_table[0][n] = c;
61 } 109 }
110
111#ifdef BYFOUR
112 /* generate crc for each value followed by one, two, and three zeros, and
113 then the byte reversal of those as well as the first table */
114 for (n = 0; n < 256; n++) {
115 c = crc_table[0][n];
116 crc_table[4][n] = REV(c);
117 for (k = 1; k < 4; k++) {
118 c = crc_table[0][c & 0xff] ^ (c >> 8);
119 crc_table[k][n] = c;
120 crc_table[k + 4][n] = REV(c);
121 }
122 }
123#endif /* BYFOUR */
124
62 crc_table_empty = 0; 125 crc_table_empty = 0;
126
127#ifdef MAKECRCH
128 /* write out CRC tables to crc32.h */
129 {
130 FILE *out;
131
132 out = fopen("crc32.h", "w");
133 if (out == NULL) return;
134 fprintf(out, "/* crc32.h -- tables for rapid CRC calculation\n");
135 fprintf(out, " * Generated automatically by crc32.c\n */\n\n");
136 fprintf(out, "local const unsigned long FAR ");
137 fprintf(out, "crc_table[TBLS][256] =\n{\n {\n");
138 write_table(out, crc_table[0]);
139# ifdef BYFOUR
140 fprintf(out, "#ifdef BYFOUR\n");
141 for (k = 1; k < 8; k++) {
142 fprintf(out, " },\n {\n");
143 write_table(out, crc_table[k]);
144 }
145 fprintf(out, "#endif\n");
146# endif /* BYFOUR */
147 fprintf(out, " }\n};\n");
148 fclose(out);
149 }
150#endif /* MAKECRCH */
63} 151}
64#else 152
153#ifdef MAKECRCH
154local void write_table(out, table)
155 FILE *out;
156 const unsigned long FAR *table;
157{
158 int n;
159
160 for (n = 0; n < 256; n++)
161 fprintf(out, "%s0x%08lxUL%s", n % 5 ? "" : " ", table[n],
162 n == 255 ? "\n" : (n % 5 == 4 ? ",\n" : ", "));
163}
164#endif /* MAKECRCH */
165
166#else /* !DYNAMIC_CRC_TABLE */
65/* ======================================================================== 167/* ========================================================================
66 * Table of CRC-32's of all single-byte values (made by make_crc_table) 168 * Tables of CRC-32s of all single-byte values, made by make_crc_table().
67 */ 169 */
68local const uLongf crc_table[256] = { 170#include "crc32.h"
69 0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L, 171#endif /* DYNAMIC_CRC_TABLE */
70 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
71 0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
72 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
73 0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
74 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
75 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
76 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
77 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
78 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
79 0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
80 0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
81 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
82 0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
83 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
84 0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
85 0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
86 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
87 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
88 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
89 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
90 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
91 0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
92 0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
93 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
94 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
95 0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
96 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
97 0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
98 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
99 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
100 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
101 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
102 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
103 0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
104 0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
105 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
106 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
107 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
108 0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
109 0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
110 0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
111 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
112 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
113 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
114 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
115 0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
116 0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
117 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
118 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
119 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
120 0x2d02ef8dL
121};
122#endif
123 172
124/* ========================================================================= 173/* =========================================================================
125 * This function can be used by asm versions of crc32() 174 * This function can be used by asm versions of crc32()
126 */ 175 */
127const uLongf * ZEXPORT get_crc_table() 176const unsigned long FAR * ZEXPORT get_crc_table()
128{ 177{
129#ifdef DYNAMIC_CRC_TABLE 178#ifdef DYNAMIC_CRC_TABLE
130 if (crc_table_empty) make_crc_table(); 179 if (crc_table_empty) make_crc_table();
131#endif 180#endif /* DYNAMIC_CRC_TABLE */
132 return (const uLongf *)crc_table; 181 return (const unsigned long FAR *)crc_table;
133} 182}
134 183
135/* ========================================================================= */ 184/* ========================================================================= */
136#define DO1(buf) crc = crc_table[((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8); 185#define DO1 crc = crc_table[0][((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8)
137#define DO2(buf) DO1(buf); DO1(buf); 186#define DO8 DO1; DO1; DO1; DO1; DO1; DO1; DO1; DO1
138#define DO4(buf) DO2(buf); DO2(buf);
139#define DO8(buf) DO4(buf); DO4(buf);
140 187
141/* ========================================================================= */ 188/* ========================================================================= */
142uLong ZEXPORT crc32(crc, buf, len) 189unsigned long ZEXPORT crc32(crc, buf, len)
143 uLong crc; 190 unsigned long crc;
144 const Bytef *buf; 191 const unsigned char FAR *buf;
145 uInt len; 192 unsigned len;
146{ 193{
147 if (buf == Z_NULL) return 0L; 194 if (buf == Z_NULL) return 0UL;
195
148#ifdef DYNAMIC_CRC_TABLE 196#ifdef DYNAMIC_CRC_TABLE
149 if (crc_table_empty) 197 if (crc_table_empty)
150 make_crc_table(); 198 make_crc_table();
151#endif 199#endif /* DYNAMIC_CRC_TABLE */
152 crc = crc ^ 0xffffffffL; 200
153 while (len >= 8) 201#ifdef BYFOUR
154 { 202 {
155 DO8(buf); 203 u4 endian;
156 len -= 8; 204
205 endian = 1;
206 if (*((unsigned char *)(&endian)))
207 return crc32_little(crc, buf, len);
208 else
209 return crc32_big(crc, buf, len);
210 }
211#else /* !BYFOUR */
212 crc = crc ^ 0xffffffffUL;
213 while (len >= 8) {
214 DO8;
215 len -= 8;
216 }
217 if (len) do {
218 DO1;
219 } while (--len);
220 return crc ^ 0xffffffffUL;
221#endif /* BYFOUR */
222}
223
224#ifdef BYFOUR
225
226/* ========================================================================= */
227#define DOLIT4 c ^= *buf4++; \
228 c = crc_table[3][c & 0xff] ^ crc_table[2][(c >> 8) & 0xff] ^ \
229 crc_table[1][(c >> 16) & 0xff] ^ crc_table[0][c >> 24]
230#define DOLIT32 DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4
231
232/* ========================================================================= */
233local unsigned long crc32_little(crc, buf, len)
234 unsigned long crc;
235 const unsigned char FAR *buf;
236 unsigned len;
237{
238 register u4 c;
239 register const u4 FAR *buf4;
240
241 c = (u4)crc;
242 c = ~c;
243 while (len && ((int)buf & 3)) {
244 c = crc_table[0][(c ^ *buf++) & 0xff] ^ (c >> 8);
245 len--;
246 }
247
248 buf4 = (const u4 FAR *)buf;
249 while (len >= 32) {
250 DOLIT32;
251 len -= 32;
252 }
253 while (len >= 4) {
254 DOLIT4;
255 len -= 4;
157 } 256 }
257 buf = (const unsigned char FAR *)buf4;
258
158 if (len) do { 259 if (len) do {
159 DO1(buf); 260 c = crc_table[0][(c ^ *buf++) & 0xff] ^ (c >> 8);
160 } while (--len); 261 } while (--len);
161 return crc ^ 0xffffffffL; 262 c = ~c;
263 return (unsigned long)c;
162} 264}
265
266/* ========================================================================= */
267#define DOBIG4 c ^= *++buf4; \
268 c = crc_table[4][c & 0xff] ^ crc_table[5][(c >> 8) & 0xff] ^ \
269 crc_table[6][(c >> 16) & 0xff] ^ crc_table[7][c >> 24]
270#define DOBIG32 DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4
271
272/* ========================================================================= */
273local unsigned long crc32_big(crc, buf, len)
274 unsigned long crc;
275 const unsigned char FAR *buf;
276 unsigned len;
277{
278 register u4 c;
279 register const u4 FAR *buf4;
280
281 c = REV((u4)crc);
282 c = ~c;
283 while (len && ((int)buf & 3)) {
284 c = crc_table[4][(c >> 24) ^ *buf++] ^ (c << 8);
285 len--;
286 }
287
288 buf4 = (const u4 FAR *)buf;
289 buf4--;
290 while (len >= 32) {
291 DOBIG32;
292 len -= 32;
293 }
294 while (len >= 4) {
295 DOBIG4;
296 len -= 4;
297 }
298 buf4++;
299 buf = (const unsigned char FAR *)buf4;
300
301 if (len) do {
302 c = crc_table[4][(c >> 24) ^ *buf++] ^ (c << 8);
303 } while (--len);
304 c = ~c;
305 return (unsigned long)(REV(c));
306}
307
308#endif /* BYFOUR */