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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#include <sys/types.h>
/*
* Fast CRC32 calculation algorithm suggested by Ferenc Rakoczi
* (ferenc.rakoczi@sun.com). The basic idea is to look at it
* four bytes (one word) at a time, using four tables. The
* standard algorithm in RFC 3309 uses one table.
*/
/*
* SCTP uses reflected/reverse polynomial CRC32 with generating
* polynomial 0x1EDC6F41L
*/
#define SCTP_POLY 0x1EDC6F41L
/* The four CRC tables. */
static uint32_t crctab[4][256];
static uint32_t
reflect_32(uint32_t b)
{
int i;
uint32_t rw = 0;
for (i = 0; i < 32; i++) {
if (b & 1) {
rw |= 1 << (31 - i);
}
b >>= 1;
}
return (rw);
}
#ifdef _BIG_ENDIAN
/*
* This function is only used for big endian processor.
*/
static uint32_t
flip32(uint32_t w)
{
return (((w >> 24) | ((w >> 8) & 0xff00) | ((w << 8) & 0xff0000) |
(w << 24)));
}
#endif
void
sctp_crc32_init(void)
{
uint32_t i, j, k, crc;
for (i = 0; i < 256; i++) {
crc = reflect_32(i);
for (k = 0; k < 4; k++) {
for (j = 0; j < 8; j++) {
crc = (crc & 0x80000000) ?
(crc << 1) ^ SCTP_POLY : crc << 1;
}
#ifdef _BIG_ENDIAN
crctab[3 - k][i] = flip32(reflect_32(crc));
#else
crctab[k][i] = reflect_32(crc);
#endif
}
}
}
static void
sctp_crc_byte(uint32_t *crcptr, const uint8_t *buf, int len)
{
uint32_t crc;
int i;
crc = *crcptr;
for (i = 0; i < len; i++) {
#ifdef _BIG_ENDIAN
crc = (crc << 8) ^ crctab[3][buf[i] ^ (crc >> 24)];
#else
crc = (crc >> 8) ^ crctab[0][buf[i] ^ (crc & 0xff)];
#endif
}
*crcptr = crc;
}
static void
sctp_crc_word(uint32_t *crcptr, const uint32_t *buf, int len)
{
uint32_t w, crc;
int i;
crc = *crcptr;
for (i = 0; i < len; i++) {
w = crc ^ buf[i];
crc = crctab[0][w >> 24] ^ crctab[1][(w >> 16) & 0xff] ^
crctab[2][(w >> 8) & 0xff] ^ crctab[3][w & 0xff];
}
*crcptr = crc;
}
uint32_t
sctp_crc32(uint32_t crc32, const uint8_t *buf, int len)
{
int rem;
rem = 4 - ((uintptr_t)buf) & 3;
if (rem != 0) {
if (len < rem) {
rem = len;
}
sctp_crc_byte(&crc32, buf, rem);
buf = buf + rem;
len = len - rem;
}
if (len > 3) {
sctp_crc_word(&crc32, (const uint32_t *)buf, len / 4);
}
rem = len & 3;
if (rem != 0) {
sctp_crc_byte(&crc32, buf + len - rem, rem);
}
return (crc32);
}
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