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https://github.com/notepad-plus-plus/notepad-plus-plus.git
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a896922136
git-svn-id: svn://svn.tuxfamily.org/svnroot/notepadplus/repository/trunk@896 f5eea248-9336-0410-98b8-ebc06183d4e3
122 lines
3.8 KiB
C++
122 lines
3.8 KiB
C++
// This file is part of Notepad++ project
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// Copyright (C)2003 Don HO <don.h@free.fr>
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation; either
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// version 2 of the License, or (at your option) any later version.
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//
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// Note that the GPL places important restrictions on "derived works", yet
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// it does not provide a detailed definition of that term. To avoid
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// misunderstandings, we consider an application to constitute a
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// "derivative work" for the purpose of this license if it does any of the
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// following:
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// 1. Integrates source code from Notepad++.
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// 2. Integrates/includes/aggregates Notepad++ into a proprietary executable
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// installer, such as those produced by InstallShield.
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// 3. Links to a library or executes a program that does any of the above.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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#ifndef _CRC16_H_
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#define _CRC16_H_
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#include <assert.h>
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class CRC16_ISO_3309
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{
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public :
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CRC16_ISO_3309(unsigned short polynom = 0x1021, unsigned short initVal = 0xFFFF)
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:_polynom(polynom), _initVal(initVal) {};
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~CRC16_ISO_3309(){};
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void set(unsigned short polynom, unsigned short initVal) {
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_polynom = polynom;
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_initVal = initVal;
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};
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unsigned short calculate(unsigned char *data, unsigned short count)
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{
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unsigned short fcs = _initVal;
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unsigned short d, i, k;
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for (i=0; i<count; i++)
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{
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d = *data++ << 8;
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for (k=0; k<8; k++)
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{
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if ((fcs ^ d) & 0x8000)
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fcs = (fcs << 1) ^ _polynom;
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else
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fcs = (fcs << 1);
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d <<= 1;
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}
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}
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return(fcs);
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}
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private :
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unsigned short _polynom;
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unsigned short _initVal;
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};
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const bool bits8 = true;
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const bool bits16 = false;
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class CRC16 : public CRC16_ISO_3309
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{
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public:
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CRC16(){};
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~CRC16(){};
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unsigned short calculate(const unsigned char *data, unsigned short count)
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{
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assert(data != NULL);
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assert(count != 0);
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//unsigned short wordResult;
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unsigned char *pBuffer = new unsigned char[count];
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// Reverse all bits of the byte then copy the result byte by byte in the array
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for (int i = 0 ; i < count ; i++)
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pBuffer[i] = reverseByte<unsigned char>(data[i]);
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// calculate CRC : by default polynom = 0x1021, init val = 0xFFFF)
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unsigned short wordResult = CRC16_ISO_3309::calculate(pBuffer, count);
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// Reverse the WORD bits
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wordResult = reverseByte<unsigned short>(wordResult);
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// XOR FFFF
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wordResult ^= 0xFFFF;
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// Invert MSB/LSB
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wordResult = wordResult << 8 | wordResult >> 8 ;
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delete [] pBuffer;
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return wordResult;
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};
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private:
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template <class IntType>
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IntType reverseByte(IntType val2Reverses)
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{
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IntType reversedValue = 0;
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long mask = 1;
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int nBits = sizeof(val2Reverses) * 8;
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for (int i = 0 ; i < nBits ; i++)
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if ((mask << i) & val2Reverses)
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reversedValue += (mask << (nBits - 1 - i));
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return reversedValue;
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};
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};
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#endif |