58 lines
1.1 KiB
C++
58 lines
1.1 KiB
C++
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//
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// MODULE: CRCCOMPUTE.CPP
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//
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// PURPOSE: CRC Calculator
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//
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// PROJECT: Generic Troubleshooter DLL for Microsoft AnswerPoint
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//
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// COMPANY: Saltmine Creative, Inc. (206)-284-7511 support@saltmine.com
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//
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// AUTHOR: Roman Mach (based on existing CRC designs)
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//
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// ORIGINAL DATE: 8/7/97
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//
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// NOTES:
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// 1.
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//
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// Version Date By Comments
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//--------------------------------------------------------------------
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// V0.2 8/7/97 RM Local Version for Memphis
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// V0.3 04/09/98 JM/OK+ Local Version for NT5
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//
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#include "stdafx.h"
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#include "crc.h"
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void CCRC::BuildCrcTable()
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{
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DWORD dwX;
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int y;
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DWORD dwAccum;
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for (dwX = 0; dwX < 256; dwX++)
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{
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dwAccum = dwX << 24;
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for (y = 0; y < 8; y++)
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{
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if (dwAccum & 0x80000000)
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dwAccum = (dwAccum << 1) ^ POLYNOMIAL;
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else
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dwAccum <<= 1;
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}
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dwCrcTable[dwX] = dwAccum;
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}
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return;
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}
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DWORD CCRC::ComputeCRC(LPCSTR sznBuffer, DWORD dwBufSize, DWORD dwAccum)
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{
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DWORD dwX;
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DWORD dwY;
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// DWORD dwAccum = 0xFFFFFFFF;
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for (dwX = 0; dwX < dwBufSize; dwX++)
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{
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dwY = ((dwAccum >> 24) ^ *sznBuffer++) & 0xFF;
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dwAccum = (dwAccum << 8) ^ dwCrcTable[dwY];
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}
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return dwAccum;
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}
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