56 lines
1.3 KiB
C
56 lines
1.3 KiB
C
/* (C) 1998 Microsoft Corp.
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*
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* cbchash.h
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*
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* Header for CBC64 hash function.
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*/
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#ifndef __CBCHASH_H
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#define __CBCHASH_H
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// Alpha must be odd.
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#define CBC_RandomOddAlpha 0xF90919A1
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#define CBC_RandomBeta 0xF993291A
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// Holds state variables for CBC64, to allow FirstCBC64() and NextCBC64()
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// behavior using the passed context.
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typedef struct {
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// Private variable to maintain state.
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UINT32 Datum;
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// Current key values. These are public for reading by the caller.
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UINT32 Key1, Key2;
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// Current plain checksum value. This is public for reading.
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UINT32 Checksum;
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} CBC64Context;
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extern const UINT32 CBC_AB[2];
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extern const UINT32 CBC_CD[2];
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void __fastcall NextCBC64(CBC64Context *, UINT32 *, unsigned);
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__inline void __fastcall FirstCBC64(
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CBC64Context *pContext,
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UINT32 *pData,
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unsigned NumDWORDBlocks)
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{
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pContext->Key1 = pContext->Key2 = pContext->Datum = CBC_RandomOddAlpha *
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(*pData) + CBC_RandomBeta;
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pContext->Key1 = (pContext->Key1 << 1) ^
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(CBC_CD[(pContext->Key1 & 0x80000000) >> 31]);
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pContext->Key2 = (pContext->Key2 << 1) ^
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(CBC_AB[(pContext->Key2 & 0x80000000) >> 31]);
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pContext->Checksum = 0;
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NextCBC64(pContext, pData + 1, NumDWORDBlocks - 1);
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}
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#endif // !defined(__CBCHASH_H)
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