Source code of Windows XP (NT5)
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/*++
Copyright (c) 1996 Microsoft Corporation� 1998 Seagate Software, Inc. All rights reserved.
Module Name:
wsbfile.h
Abstract:
This module defines very specific CRC algorithm code
Author:
Christopher J. Timmes [ctimmes@avail.com] 23 Jun 1997
Revision History: Michael Lotz [lotz] 30-Sept-1997
--*/
#ifndef _WSBFILE_H
#define _WSBFILE_H
extern unsigned long crc_32_tab[];
extern "C"{externWSB_EXPORTHRESULT WsbCRCReadFile ( BYTE* pchCurrent, ULONG* oldcrc32 );}
// ---------- implementation code for WsbCalcCRCofFile() ----------
// This is the CRC calculation algorythm.
// It is called with the current byte in the file and the current CRC value,
// and uses the 'crc_32_tab[]' table. The crc_32_tab[] look up table is externed above and resides
// in the wsbfile.obj object module. Any function or method using the macro below must include
// the wsbfile.obj in the link list.
//
// For example, it can be used in the following way:
// unsigned long ulCRC ;
//
// INITIALIZE_CRC( ulCRC );
// for( all *bytes* that are to be CRCed )
// CALC_CRC( current_byte, ulCRC );
// FINIALIZE_CRC( ulCRC );
//
// at this point ulCRC is the CRC value and can be used as the calculated CRC value
//
#define INITIALIZE_CRC( crc ) ((crc) = 0xFFFFFFFF )
#define CALC_CRC( octet, crc ) ((crc) = ( crc_32_tab[((crc)^ (octet)) & 0xff] ^ ((crc) >> 8) ) )
#define FINIALIZE_CRC( crc ) ((crc) = ~(crc) )
// ---------------------- Defines to identify the CRC calculation types -------------
#define WSB_CRC_CALC_NONE 0x00000000
// Identify this algorithm and the Microsoft 32 bit CRC calculation
#define WSB_CRC_CALC_MICROSOFT_32 0x00000001
#endif // _WSBFILE_H
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