159 lines
3.1 KiB
C++
159 lines
3.1 KiB
C++
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//***************************************************************************
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//
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// (c) 1999-2001 by Microsoft Corp. All Rights Reserved.
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//
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// crc64.cpp
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//
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// cvadai 12-Nov-99 created.
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//
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//***************************************************************************
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#define _CRC64_CPP_
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#include "precomp.h"
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#include <crc64.h>
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hash_t CRC64::CrcXor[256];
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hash_t CRC64::Poly[64+1];
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BOOL CRC64::bInit = FALSE;
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unsigned long GetHIDWord(__int64 in)
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{
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unsigned long lRet = (long)(in >> 0x20);
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return lRet;
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}
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unsigned long GetLODWord(__int64 in)
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{
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unsigned long lRet = (long)(in & 0xFFFFFFFF);
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return lRet;
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}
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__int64 MakeInt64( long val1, long val2)
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{
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__int64 ret = 0;
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ret = ((__int64)val1 << 0x20) + val2;
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return ret;
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}
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//***************************************************************************
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//
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// CRC64::GenerateHashValue
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//
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//***************************************************************************
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hash_t CRC64::GenerateHashValue(const wchar_t *p)
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{
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hash_t tRet = 0;
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if (!p)
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return 0;
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if (!bInit)
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{
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Initialize();
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bInit = TRUE;
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}
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long h1, h2;
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h1 = HINIT1, h2 = HINIT2;
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int s = 64-40;
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hint_t m = (hint_t)-1 >> (0);
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h1 &= m;
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while (*p)
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{
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int char1 = towupper(*p);
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int i = (h1 >> s) & 255;
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h1 = ((h1 << 8) & m) ^ (int)(h2 >> 24) ^ GetHIDWord(CrcXor[i]);
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h2 = (h2 << 8) ^ char1 ^ GetLODWord(CrcXor[i]);
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++p;
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}
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tRet = MakeInt64(h1, h2);
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return(tRet);
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}
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//***************************************************************************
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//
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// CRC64::Initialize
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//
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//***************************************************************************
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void CRC64::Initialize(void)
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{
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int i;
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/*
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* Polynomials to use for various crc sizes. Start with the 64 bit
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* polynomial and shift it right to generate the polynomials for fewer
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* bits. Note that the polynomial for N bits has no bit set above N-8.
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* This allows us to do a simple table-driven CRC.
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*/
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hint_t h1 = POLY1, h2 = POLY2;
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Poly[64] = MakeInt64(POLY1, POLY2);
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for (i = 63; i >= 16; --i)
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{
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h1 = (GetHIDWord(Poly[i+1])) >> 1;
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h2 = (GetLODWord(Poly[i+1])) >> 1 | ((GetHIDWord(Poly[i+1] ) & 1) << 31) | 1;
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Poly[i] = MakeInt64(h1, h2);
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}
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for (i = 0; i < 256; ++i)
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{
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int j;
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int v = i;
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h1 = 0, h2 = 0;
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for (j = 0; j < 8; ++j, (v <<= 1)) {
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h1 <<= 1;
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if (h2 & 0x80000000UL)
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h1 |= 1;
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h2 = (h2 << 1);
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if (v & 0x80) {
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h1 ^= GetHIDWord(Poly[64]);
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h2 ^= GetLODWord(Poly[64]);
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}
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}
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CrcXor[i] = MakeInt64(h1, h2);
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}
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}
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//***************************************************************************
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//
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// CRC64::RMalloc
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//
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//***************************************************************************
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void * CRC64::RMalloc(int bytes)
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{
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static wchar_t *RBuf = NULL;
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static int RSize = 0;
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bytes = (bytes + 3) & ~3;
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if (bytes > RSize)
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{
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RBuf = (wchar_t *)malloc(65536);
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RSize = 65536;
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}
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RBuf += bytes;
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RSize -= bytes;
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return(RBuf - bytes);
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}
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