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