1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 #include <sys/types.h>
27
28 /*
29 * Fast CRC32 calculation algorithm suggested by Ferenc Rakoczi
30 * (ferenc.rakoczi@sun.com). The basic idea is to look at it
31 * four bytes (one word) at a time, using four tables. The
32 * standard algorithm in RFC 3309 uses one table.
33 */
34
35 /*
36 * SCTP uses reflected/reverse polynomial CRC32 with generating
37 * polynomial 0x1EDC6F41L
38 */
39 #define SCTP_POLY 0x1EDC6F41L
40
41 /* The four CRC tables. */
42 static uint32_t crctab[4][256];
43
44 static uint32_t
reflect_32(uint32_t b)45 reflect_32(uint32_t b)
46 {
47 int i;
48 uint32_t rw = 0;
49
50 for (i = 0; i < 32; i++) {
51 if (b & 1) {
52 rw |= 1 << (31 - i);
53 }
54 b >>= 1;
55 }
56 return (rw);
57 }
58
59 #ifdef _BIG_ENDIAN
60
61 /*
62 * This function is only used for big endian processor.
63 */
64 static uint32_t
flip32(uint32_t w)65 flip32(uint32_t w)
66 {
67 return (((w >> 24) | ((w >> 8) & 0xff00) | ((w << 8) & 0xff0000) |
68 (w << 24)));
69 }
70
71 #endif
72
73 void
sctp_crc32_init(void)74 sctp_crc32_init(void)
75 {
76 uint32_t i, j, k, crc;
77
78 for (i = 0; i < 256; i++) {
79 crc = reflect_32(i);
80 for (k = 0; k < 4; k++) {
81 for (j = 0; j < 8; j++) {
82 crc = (crc & 0x80000000) ?
83 (crc << 1) ^ SCTP_POLY : crc << 1;
84 }
85 #ifdef _BIG_ENDIAN
86 crctab[3 - k][i] = flip32(reflect_32(crc));
87 #else
88 crctab[k][i] = reflect_32(crc);
89 #endif
90 }
91 }
92 }
93
94 static void
sctp_crc_byte(uint32_t * crcptr,const uint8_t * buf,int len)95 sctp_crc_byte(uint32_t *crcptr, const uint8_t *buf, int len)
96 {
97 uint32_t crc;
98 int i;
99
100 crc = *crcptr;
101 for (i = 0; i < len; i++) {
102 #ifdef _BIG_ENDIAN
103 crc = (crc << 8) ^ crctab[3][buf[i] ^ (crc >> 24)];
104 #else
105 crc = (crc >> 8) ^ crctab[0][buf[i] ^ (crc & 0xff)];
106 #endif
107 }
108 *crcptr = crc;
109 }
110
111 static void
sctp_crc_word(uint32_t * crcptr,const uint32_t * buf,int len)112 sctp_crc_word(uint32_t *crcptr, const uint32_t *buf, int len)
113 {
114 uint32_t w, crc;
115 int i;
116
117 crc = *crcptr;
118 for (i = 0; i < len; i++) {
119 w = crc ^ buf[i];
120 crc = crctab[0][w >> 24] ^ crctab[1][(w >> 16) & 0xff] ^
121 crctab[2][(w >> 8) & 0xff] ^ crctab[3][w & 0xff];
122 }
123 *crcptr = crc;
124 }
125
126 uint32_t
sctp_crc32(uint32_t crc32,const uint8_t * buf,int len)127 sctp_crc32(uint32_t crc32, const uint8_t *buf, int len)
128 {
129 int rem;
130
131 rem = 4 - ((uintptr_t)buf) & 3;
132 if (rem != 0) {
133 if (len < rem) {
134 rem = len;
135 }
136 sctp_crc_byte(&crc32, buf, rem);
137 buf = buf + rem;
138 len = len - rem;
139 }
140
141 if (len > 3) {
142 sctp_crc_word(&crc32, (const uint32_t *)buf, len / 4);
143 }
144
145 rem = len & 3;
146 if (rem != 0) {
147 sctp_crc_byte(&crc32, buf + len - rem, rem);
148 }
149 return (crc32);
150 }
151