78 lines
1.8 KiB
C
78 lines
1.8 KiB
C
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/***************************************************************************
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Name : CRC.C
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Comment : HDLC encoding routines
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Functions: (see Prototypes just below)
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Copyright (c) Microsoft Corp. 1991 1992 1993
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Revision Log
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Date Name Description
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-------- ----- ---------------------------------------------------------
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***************************************************************************/
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#include "prep.h"
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#include "decoder.h"
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#include "debug.h"
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#include "glbproto.h"
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#define FILEID FILEID_CRC
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WORD CODEBASED CRCTab[16] =
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{ 0x0000, 0x1081, 0x2102, 0x3183,
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0x4204, 0x5285, 0x6306, 0x7387,
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0x8408, 0x9489, 0xa50a, 0xb58b,
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0xc60c, 0xd68d, 0xe70e, 0xf78f };
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WORD SWECMEXP CalcCRC(PThrdGlbl pTG, LPBYTE lpbSrc, USHORT cbSrc)
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{
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#if !defined(PORTABLE_CODE) || defined(CLASS1_TEST_HOOKS)
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WORD wRet;
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#endif
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#ifdef PORTABLE_CODE
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USHORT wTempChar=0, j=0, wTempCRC=(USHORT)-1;
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USHORT SourceIndex;
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LPBYTE SourceAddress;
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SourceAddress = lpbSrc;
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for(SourceIndex = cbSrc;SourceIndex > 0; SourceIndex--) {
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wTempChar = (USHORT) *SourceAddress++;
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j = (wTempCRC ^ wTempChar) & 0x0f;
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wTempCRC = (wTempCRC >> 4) ^ CRCTab[j];
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wTempChar >>= 4;
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j = (wTempCRC ^ wTempChar) & 0x0f;
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wTempCRC = (wTempCRC >> 4) ^ CRCTab[j];
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}
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wTempCRC = ~wTempCRC;
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#endif
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#ifdef CLASS1_TEST_HOOKS
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if (wRet == wTempCRC) {
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// DEBUGMSG(1,("CalcCRC: Assembly and C CRC both = %X\n", wTempCRC));
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}
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else
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ERRORMSG(("CalcCRC: Assembly CRC = %X; C CRC = %X\n", wRet, wTempCRC));
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#endif
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#ifdef PORTABLE_CODE
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return wTempCRC;
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#else
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return wRet;
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#endif
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}
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