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
123
124
125
126
127
128
129
130
131
132
|
/* Based on "File Verification Using CRC" by Mark R. Nelson in Dr. Dobbs'
* Journal, May 1992, pp. 64-67. This algorithm generates the same CRC
* values as ZMODEM and PKZIP
*
* Copyright (C) 2002-2005 SBE, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/types.h>
#include "pmcc4_sysdep.h"
#include "sbecom_inline_linux.h"
#include "sbe_promformat.h"
/* defines */
#define CRC32_POLYNOMIAL 0xEDB88320L
#define CRC_TABLE_ENTRIES 256
static u_int32_t crcTableInit;
#ifdef STATIC_CRC_TABLE
static u_int32_t CRCTable[CRC_TABLE_ENTRIES];
#endif
/***************************************************************************
*
* genCrcTable - fills in CRCTable, as used by sbeCrc()
*
* RETURNS: N/A
*
* ERRNO: N/A
***************************************************************************/
static void
genCrcTable(u_int32_t *CRCTable)
{
int ii, jj;
u_int32_t crc;
for (ii = 0; ii < CRC_TABLE_ENTRIES; ii++) {
crc = ii;
for (jj = 8; jj > 0; jj--) {
if (crc & 1)
crc = (crc >> 1) ^ CRC32_POLYNOMIAL;
else
crc >>= 1;
}
CRCTable[ii] = crc;
}
crcTableInit++;
}
/***************************************************************************
*
* sbeCrc - generates a CRC on a given buffer, and initial CRC
*
* This routine calculates the CRC for a buffer of data using the
* table lookup method. It accepts an original value for the crc,
* and returns the updated value. This permits "catenation" of
* discontiguous buffers. An original value of 0 for the "first"
* buffer is the norm.
*
* Based on "File Verification Using CRC" by Mark R. Nelson in Dr. Dobb's
* Journal, May 1992, pp. 64-67. This algorithm generates the same CRC
* values as ZMODEM and PKZIP.
*
* RETURNS: calculated crc of block
*
*/
void
sbeCrc(u_int8_t *buffer, /* data buffer to crc */
u_int32_t count, /* length of block in bytes */
u_int32_t initialCrc, /* starting CRC */
u_int32_t *result)
{
u_int32_t *tbl = 0;
u_int32_t temp1, temp2, crc;
/*
* if table not yet created, do so. Don't care about "extra" time
* checking this every time sbeCrc() is called, since CRC calculations
* are already time consuming
*/
if (!crcTableInit) {
#ifdef STATIC_CRC_TABLE
tbl = &CRCTable;
genCrcTable(tbl);
#else
tbl = (u_int32_t *) OS_kmalloc(CRC_TABLE_ENTRIES * sizeof(u_int32_t));
if (tbl == 0) {
*result = 0; /* dummy up return value due to malloc
* failure */
return;
}
genCrcTable(tbl);
#endif
}
/* inverting bits makes ZMODEM & PKZIP compatible */
crc = initialCrc ^ 0xFFFFFFFFL;
while (count-- != 0) {
temp1 = (crc >> 8) & 0x00FFFFFFL;
temp2 = tbl[((int) crc ^ *buffer++) & 0xff];
crc = temp1 ^ temp2;
}
crc ^= 0xFFFFFFFFL;
*result = crc;
#ifndef STATIC_CRC_TABLE
crcTableInit = 0;
OS_kfree(tbl);
#endif
}
/*** End-of-File ***/
|
