linearcodedlg.cpp

一种较好的线性编码方法.效率高,而且在解码时正确率较高.

// LinearCodeDlg.cpp : implementation file
//

#include "stdafx.h"
#include "LinearCode.h"
#include "LinearCodeDlg.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

/////////////////////////////////////////////////////////////////////////////
// CLinearCodeDlg dialog

CLinearCodeDlg::CLinearCodeDlg(CWnd* pParent /*=NULL*/)
	: CDialog(CLinearCodeDlg::IDD, pParent)
{
	//{{AFX_DATA_INIT(CLinearCodeDlg)
	m_sData = _T("");
	//}}AFX_DATA_INIT
	// Note that LoadIcon does not require a subsequent DestroyIcon in Win32
	m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);
}

void CLinearCodeDlg::DoDataExchange(CDataExchange* pDX)
{
	CDialog::DoDataExchange(pDX);
	//{{AFX_DATA_MAP(CLinearCodeDlg)
	DDX_Text(pDX, IDC_DATA, m_sData);
	//}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CLinearCodeDlg, CDialog)
	//{{AFX_MSG_MAP(CLinearCodeDlg)
	ON_WM_PAINT()
	ON_WM_QUERYDRAGICON()
	ON_BN_CLICKED(IDC_ENCODE, OnEncode)
	ON_BN_CLICKED(IDC_DECODE, OnDecode)
	//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CLinearCodeDlg message handlers

BOOL CLinearCodeDlg::OnInitDialog()
{
	CDialog::OnInitDialog();

	// Set the icon for this dialog.  The framework does this automatically
	//  when the application's main window is not a dialog
	SetIcon(m_hIcon, TRUE);			// Set big icon
	SetIcon(m_hIcon, FALSE);		// Set small icon
	
	// TODO: Add extra initialization here
	
	return TRUE;  // return TRUE  unless you set the focus to a control
}

// If you add a minimize button to your dialog, you will need the code below
//  to draw the icon.  For MFC applications using the document/view model,
//  this is automatically done for you by the framework.

void CLinearCodeDlg::OnPaint() 
{
	if (IsIconic())
	{
		CPaintDC dc(this); // device context for painting

		SendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0);

		// Center icon in client rectangle
		int cxIcon = GetSystemMetrics(SM_CXICON);
		int cyIcon = GetSystemMetrics(SM_CYICON);
		CRect rect;
		GetClientRect(&rect);
		int x = (rect.Width() - cxIcon + 1) / 2;
		int y = (rect.Height() - cyIcon + 1) / 2;

		// Draw the icon
		dc.DrawIcon(x, y, m_hIcon);
	}
	else
	{
		CDialog::OnPaint();
	}
}

// The system calls this to obtain the cursor to display while the user drags
//  the minimized window.
HCURSOR CLinearCodeDlg::OnQueryDragIcon()
{
	return (HCURSOR) m_hIcon;
}

bool GetA3(BYTE bRaw)
{
	int num = 0;	
	
	// 与该监督位对应的信息位
	int A3[5] = {3, 4, 5, 6, 7};

	// 统计信息位的奇偶性
	for (int i = 0; i < 5; i++)
	{
		int R = 1 << A3[i];
		if ((bRaw & R) == R)
			num++;
	}

	// 计算第1位监督位的取值，使之与对应信息位能够完成偶校验
	float temp = num / 2.0f;
	if (temp == (int)(num / 2))
        return false;
	else
		return true;
}

bool GetA2(BYTE bRaw)
{
	int num = 0;

	// 与该监督位对应的信息位
	int A2[5] = {0, 1, 2, 6, 7};

	// 统计信息位的奇偶性
	for (int i = 0; i < 5; i++)
	{
		int R = 1 << A2[i];
		if ((bRaw & R) == R)
			num++;
	}

	// 计算第1位监督位的取值，使之与对应信息位能够完成偶校验
	float temp = num / 2.0f;
	if (temp == (int)(num / 2))
        return false;
	else
		return true;
}

bool GetA1(BYTE bRaw)
{
	int num = 0;
	
	// 与该监督位对应的信息位
	int A1[5] = {1, 2, 4, 5, 6};

	// 统计信息位的奇偶性
	for (int i = 0; i < 5; i++)
	{
		int R = 1 << A1[i];
		if ((bRaw & R) == R)
			num++;
	}

	// 计算第1位监督位的取值，使之与对应信息位能够完成偶校验
	float temp = num / 2.0f;
	if (temp == (int)(num / 2))
        return false;
	else
		return true;
}

bool GetA0(BYTE bRaw)
{
	int num = 0;
	
	// 与该监督位对应的信息位
	int A0[5] = {0, 2, 3, 5, 7};

	// 统计信息位的奇偶性
	for (int i = 0; i < 5; i++)
	{
		int R = 1 << A0[i];
		if ((bRaw & R) == R)
			num++;
	}

	// 计算第1位监督位的取值，使之与对应信息位能够完成偶校验
	float temp = num / 2.0f;
	if (temp == (int)(num / 2))
        return false;
	else
		return true;
}

void Encode(BYTE* pbRaw, BYTE* pbCode, int nRawLen)
{
	// 中间变量
	int point = 0;
	int num = 0;
	BYTE temp1 = 0;
	BYTE temp2 = 0;

	for (int i = 0; i < nRawLen; i++)
	{
		temp1 = pbRaw[i];
		num += 8;

		// 保存原始信息位和计算出来的监督位到编码流
		if (num == 8)
		{
			pbCode[point] = temp1;
			point++;
		}

		if (num == 20)
		{
			pbCode[point] = (unsigned char)((temp2 << 4) | (temp1 >> 4));
			point++;
		}

		// 计算监督位
		temp2 = 0;
		temp1 = pbRaw[i];
		if (GetA3(temp1) == true)
			temp2 |= 8;
		if (GetA2(temp1) == true)
			temp2 |= 4;
		if (GetA1(temp1) == true)
			temp2 |= 2;
		if (GetA0(temp1) == true)
			temp2 |= 1;
		num += 4;

		// 指针修正
		if (num == 24)
		{
			pbCode[point] = (unsigned char)((temp1 << 4) | temp2);
			point++;
			num = 0;
		}
	}

	// 原始信息流为奇数时在编码流末尾做补0处理
	if (num == 12)
		pbCode[point] = (unsigned char)(temp2 << 4);	
}

void Decode(BYTE* pbRaw, BYTE* pbCode, int nRawLen)
{
	// 各编码位所对应的校正子取值，校正子为0时校验正确
	BYTE A[12] = {1, 2, 4, 8, 5, 6, 7, 9, 10, 11, 14, 13};

	// 中间变量
	BYTE bRet;
	int num = 0;
	int point = 0;
	int S0, S1, S2, S3;
	bool temp1;
	BYTE temp3, temp4;
	BYTE bInfo = 0;
	BYTE bCheck = 0;

	for (int i = 0; i < nRawLen; i++)
	{
		// 提取信息位和监督位
		if (num == 0)
		{
			bInfo = pbCode[point];
			bCheck = pbCode[point + 1];
		}

		if (num == 12)
		{
			temp3 = pbCode[point];
			temp4 = pbCode[point + 1];
			bInfo = (unsigned char)((temp3 << 4) | (temp4 >> 4));
			temp4 = pbCode[point + 1];
			bCheck = (unsigned char)(temp4 << 4);
		}

		// 计算S3
		temp1 = GetA3(bInfo);
		temp3 = bCheck;
		if (((temp3 & 0x80) >> 7) == 1)
		{
			if (temp1 == true)
				S3 = 0;
			else
				S3 = 1;
		}
		else
		{
			if (temp1 == true)
				S3 = 1;
			else
				S3 = 0;
		}

		// 计算S2
		temp1 = GetA2(bInfo);
		temp3 = bCheck;
		if (((temp3 & 0x40) >> 6) == 1)
		{
			if (temp1 == true)
				S2 = 0;
			else
				S2 = 1;
		}
		else
		{
			if (temp1 == true)
				S2 = 1;
			else
				S2 = 0;
		}

		// 计算S1
		temp1 = GetA1(bInfo);
		temp3 = bCheck;
		if (((temp3 & 0x20) >> 5) == 1)
		{
			if (temp1 == true)
				S1 = 0;
			else
				S1 = 1;
		}
		else
		{
			if (temp1 == true)
				S1 = 1;
			else
				S1 = 0;
		}

		// 计算S0
		temp1 = GetA0(bInfo);
		temp3 = bCheck;
		if (((temp3 & 0x10) >> 4) == 1)
		{
			if (temp1 == true)
				S0 = 0;
			else
				S0 = 1;
		}
		else
		{
			if (temp1 == true)
				S0 = 1;
			else
				S0 = 0;
		}

		// 得到校正子
		bRet = 0;
		bRet |= S3 << 3;
		bRet |= S2 << 2;
		bRet |= S1 << 1;
		bRet |= S0;
		
		if (bRet == 0)
		{
			// 无需纠错
			pbRaw[i] = bInfo; 
		}
		else
		{
			// 得到错误位置
            for (int j = 0; j < 12; j++)
			{
				if (A[j] == bRet)
					break;
			}

			if (j <= 3)
			{
				// 监督位无须纠错
                pbRaw[i] = bInfo; 
			}
			else
			{
				// 信息位反码纠错
				temp3 = bInfo;
				temp3 &= 1 << (j - 4);
				temp3 = (unsigned char)(~temp3);
				pbRaw[i] = (unsigned char)((temp3 & bInfo) | (temp3 & (1 << (j - 4))));
			}
		}

		// 修正计数器
		point++;
		num += 12;
		if (num == 24)
		{
			num = 0;
			point++;
		}
	}
}


void CLinearCodeDlg::OnEncode() 
{
	UpdateData(TRUE);
	BYTE TempIn[1024];
	BYTE TempOut[1024];
    memcpy((char*)TempIn, m_sData, m_sData.GetLength());
	memset((char*)TempOut,0,sizeof(TempOut));
	Encode(TempIn,TempOut,m_sData.GetLength());
	m_sData = CString(TempOut);
	UpdateData(FALSE);
}

void CLinearCodeDlg::OnDecode() 
{
	UpdateData(TRUE);
	BYTE TempIn[1024];
	BYTE TempOut[1024];
    memcpy((char*)TempIn, m_sData, m_sData.GetLength());
	memset((char*)TempOut,0,sizeof(TempOut));
	int nRawLen = (int)(m_sData.GetLength() * 2 / 3.0f);
	Decode((LPBYTE)TempOut, (LPBYTE)TempIn, nRawLen);
	m_sData = CString(TempOut);
	UpdateData(FALSE);
}