1 /* Based on "File Verification Using CRC" by Mark R. Nelson in Dr. Dobbs'
2 * Journal, May 1992, pp. 64-67. This algorithm generates the same CRC
3 * values as ZMODEM and PKZIP
5 * Copyright (C) 2002-2005 SBE, Inc.
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
18 #include <linux/types.h>
19 #include "pmcc4_sysdep.h"
20 #include "sbecom_inline_linux.h"
21 #include "sbe_promformat.h"
24 #define CRC32_POLYNOMIAL 0xEDB88320L
25 #define CRC_TABLE_ENTRIES 256
29 static u_int32_t crcTableInit;
31 #ifdef STATIC_CRC_TABLE
32 static u_int32_t CRCTable[CRC_TABLE_ENTRIES];
37 /***************************************************************************
39 * genCrcTable - fills in CRCTable, as used by sbeCrc()
44 ***************************************************************************/
47 genCrcTable (u_int32_t *CRCTable)
52 for (ii = 0; ii < CRC_TABLE_ENTRIES; ii++)
55 for (jj = 8; jj > 0; jj--)
58 crc = (crc >> 1) ^ CRC32_POLYNOMIAL;
69 /***************************************************************************
71 * sbeCrc - generates a CRC on a given buffer, and initial CRC
73 * This routine calculates the CRC for a buffer of data using the
74 * table lookup method. It accepts an original value for the crc,
75 * and returns the updated value. This permits "catenation" of
76 * discontiguous buffers. An original value of 0 for the "first"
79 * Based on "File Verification Using CRC" by Mark R. Nelson in Dr. Dobb's
80 * Journal, May 1992, pp. 64-67. This algorithm generates the same CRC
81 * values as ZMODEM and PKZIP.
83 * RETURNS: calculated crc of block
88 sbeCrc (u_int8_t *buffer, /* data buffer to crc */
89 u_int32_t count, /* length of block in bytes */
90 u_int32_t initialCrc, /* starting CRC */
94 u_int32_t temp1, temp2, crc;
97 * if table not yet created, do so. Don't care about "extra" time
98 * checking this everytime sbeCrc() is called, since CRC calculations are
99 * already time consuming
103 #ifdef STATIC_CRC_TABLE
107 tbl = (u_int32_t *) OS_kmalloc (CRC_TABLE_ENTRIES * sizeof (u_int32_t));
110 *result = 0; /* dummy up return value due to malloc
117 /* inverting bits makes ZMODEM & PKZIP compatible */
118 crc = initialCrc ^ 0xFFFFFFFFL;
122 temp1 = (crc >> 8) & 0x00FFFFFFL;
123 temp2 = tbl[((int) crc ^ *buffer++) & 0xff];
131 #ifndef STATIC_CRC_TABLE
137 /*** End-of-File ***/