forked from sin365/AxibugEmuOnline
72 lines
2.6 KiB
C++
72 lines
2.6 KiB
C++
//
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// CRCチェック用ライブラリクラス
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//
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#include "Crclib.h"
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BOOL CRC::m_Init = FALSE;
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BOOL CRC::m_InitRev = FALSE;
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DWORD CRC::m_CrcTable[ UCHAR_MAX+1 ];
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DWORD CRC::m_CrcTableRev[ UCHAR_MAX+1 ];
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#define CRCPOLY1 0x04C11DB7UL
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#define CRCPOLY2 0xEDB88320UL
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DWORD CRC::Crc( INT size, LPBYTE c )
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{
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if( !m_Init ) {
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MakeTable();
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m_Init = TRUE;
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}
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DWORD r = 0xFFFFFFFFUL;
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while( --size >= 0 ) {
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r = (r << CHAR_BIT) ^ m_CrcTable[(BYTE)(r >> (32 - CHAR_BIT)) ^ *c++];
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}
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return ~r & 0xFFFFFFFFUL;
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}
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DWORD CRC::CrcRev( INT size, LPBYTE c )
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{
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if( !m_InitRev ) {
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MakeTableRev();
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m_InitRev = TRUE;
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}
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DWORD r = 0xFFFFFFFFUL;
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while( --size >= 0 ) {
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r = (r >> CHAR_BIT) ^ m_CrcTableRev[(BYTE)r ^ *c++];
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}
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return r ^ 0xFFFFFFFFUL;
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}
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void CRC::MakeTable()
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{
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INT i, j;
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DWORD r;
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for( i = 0; i <= UCHAR_MAX; i++ ) {
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r = (DWORD)i << (32 - CHAR_BIT);
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for( j = 0; j < CHAR_BIT; j++ ) {
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if( r & 0x80000000UL ) r = (r << 1) ^ CRCPOLY1;
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else r <<= 1;
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}
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m_CrcTable[i] = r & 0xFFFFFFFFUL;
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}
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}
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void CRC::MakeTableRev()
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{
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INT i, j;
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DWORD r;
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for( i = 0; i <= UCHAR_MAX; i++ ) {
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r = i;
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for( j = 0; j < CHAR_BIT; j++ ) {
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if( r & 1 ) r = (r >> 1) ^ CRCPOLY2;
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else r >>= 1;
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}
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m_CrcTableRev[i] = r;
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}
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}
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