Mercurial > vba-linux

     1 // LzhCRC.cpp

     2 

     3 #include "StdAfx.h"

     4 

     5 #include "LzhCRC.h"

     6 

     7 namespace NArchive {

     8 namespace NLzh {

     9 

    10 static const UInt16 kCRCPoly = 0xA001;

    11 

    12 UInt16 CCRC::Table[256];

    13 

    14 void CCRC::InitTable()

    15 {

    16   for (UInt32 i = 0; i < 256; i++)

    17   {

    18     UInt32 r = i;

    19     for (int j = 0; j < 8; j++)

    20       if (r & 1)

    21         r = (r >> 1) ^ kCRCPoly;

    22       else

    23         r >>= 1;

    24     CCRC::Table[i] = (UInt16)r;

    25   }

    26 }

    27 

    28 class CCRCTableInit

    29 {

    30 public:

    31   CCRCTableInit() { CCRC::InitTable(); }

    32 } g_CRCTableInit;

    33 

    34 void CCRC::Update(const void *data, size_t size)

    35 {

    36   UInt16 v = _value;

    37   const Byte *p = (const Byte *)data;

    38   for (; size > 0; size--, p++)

    39     v = (UInt16)(Table[((Byte)(v)) ^ *p] ^ (v >> 8));

    40   _value = v;

    41 }

    42 

    43 }}
author	Robert McIntyre <rlm@mit.edu>
date	Sat, 03 Mar 2012 10:31:27 -0600
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