C++ 循环缓冲类

  1 // MindryBuffer.cpp : 定义控制台应用程序的入口点。
  2 //
  3 
  4 #include "stdafx.h"
  5 #include <iostream>
  6 #include <string.h>
  7 using namespace std;
  8 
  9 class CMindryBuffer
 10 {
 11 public:
 12     CMindryBuffer(int iBufLenth = MindryBufferLenth);
 13     ~CMindryBuffer(void);
 14 
 15     int  ReSize(int iBufLenth);                        //重置缓冲区大小
 16     int     Read(char * pData,int iReadDataLength);    //读取指定数据
 17     int  Write(char * pData,int iWriteDataLength);    //写入指定数据
 18 
 19     void Clear();                                    //清空缓冲区
 20     int     GetCapicity();                                //获取缓冲区容量
 21     int     GetWriteAvailable();                        //缓冲区可写数据  可通过此函数判断缓冲区是否已满
 22     int     GetReadAvailable();                         //缓冲区可读数据  可通过此函数判断缓冲区是否为空    
 23 
 24 private:
 25     const static int MindryBufferLenth = 10;        //默认缓冲区长度
 26     int m_iBufLenth;                                //缓冲区
 27     int m_iWritePos;                                //写入起始位置
 28     int m_iReadPos;                                    //读取起始位置
 29     int m_iDataLenth;                                //缓冲区存放数据长度
 30     char *m_PData;                                    //缓冲区数据指针
 31 };
 32 
 33 CMindryBuffer::CMindryBuffer(int iBufLenth)
 34 {    
 35     m_PData = NULL;
 36     m_iWritePos = 0;
 37     m_iReadPos = 0;
 38     m_iDataLenth = 0;
 39     m_iBufLenth = iBufLenth;
 40     if (m_iBufLenth > 0)
 41     {
 42         m_PData = new char[m_iBufLenth];
 43     }
 44 }
 45 
 46 CMindryBuffer::~CMindryBuffer(void)
 47 {
 48     if (m_PData) 
 49     {
 50         delete [] m_PData;
 51     }
 52 }
 53 
 54 
 55 int  CMindryBuffer::Write(char * pData,int iWriteDataLength)
 56 {
 57     if (m_iBufLenth - m_iDataLenth == 0 || !m_PData )    
 58     {
 59         return 0;
 60     }
 61 
 62     int iCanWriteDataLength =  iWriteDataLength> GetWriteAvailable()? GetWriteAvailable():iWriteDataLength;
 63 
 64     int iNowWriteToEndLength = m_iBufLenth - m_iWritePos;
 65     if (iNowWriteToEndLength >= iCanWriteDataLength)
 66     {
 67         memcpy(&m_PData[m_iWritePos],pData,iCanWriteDataLength);
 68         m_iWritePos += iCanWriteDataLength;
 69     }
 70     else
 71     {
 72         memcpy(&m_PData[m_iWritePos],pData,iNowWriteToEndLength);
 73         memcpy(m_PData,&pData[iNowWriteToEndLength],iCanWriteDataLength - iNowWriteToEndLength);        
 74         m_iWritePos = iCanWriteDataLength - iCanWriteDataLength;
 75     }
 76     m_iDataLenth += iCanWriteDataLength;
 77     return iCanWriteDataLength;
 78 }
 79 
 80 int     CMindryBuffer::Read(char * pData,int iReadDataLength)
 81 {
 82     if (m_iDataLenth == 0) 
 83     {
 84         return 0;
 85     }
 86     int iCanReadDataLength = iReadDataLength>m_iDataLenth? m_iDataLenth:iReadDataLength;
 87     int iNowReadToEndLength = m_iBufLenth - m_iReadPos;
 88 
 89     if (iNowReadToEndLength >= iCanReadDataLength)
 90     {
 91         memcpy(pData,&m_PData[m_iReadPos],iCanReadDataLength);
 92         m_iReadPos += iCanReadDataLength;
 93     }
 94     else
 95     {
 96         memcpy(pData,&m_PData[m_iReadPos],iNowReadToEndLength);
 97         memcpy(&pData[iNowReadToEndLength],m_PData,iCanReadDataLength - iNowReadToEndLength);    
 98 
 99         m_iReadPos = iCanReadDataLength - iNowReadToEndLength;
100     }
101     m_iDataLenth -= iCanReadDataLength;
102     return iCanReadDataLength;
103 }
104 
105 int  CMindryBuffer::ReSize(int iBufLenth)
106 {
107     if (iBufLenth > m_iBufLenth )
108     {    
109         char * pData = new char[iBufLenth];    
110         Read(pData ,m_iDataLenth);
111     
112         delete []m_PData;
113         m_PData = pData;
114         m_iReadPos = 0;
115         m_iWritePos = m_iDataLenth;
116         m_iBufLenth = iBufLenth;
117     }
118     return  m_iDataLenth;
119 }
120 
121 void CMindryBuffer::Clear()
122 {
123     m_iReadPos = 0;
124     m_iWritePos = 0;
125     m_iDataLenth = 0;
126 }
127 
128 int    CMindryBuffer::GetCapicity()
129 {
130     return m_iBufLenth;
131 }
132 
133 int    CMindryBuffer::GetWriteAvailable()
134 {
135     return m_iBufLenth -m_iDataLenth;
136 
137 }
138 int    CMindryBuffer::GetReadAvailable()
139 {
140     return m_iDataLenth;
141 }
142 
143 int _tmain(int argc, _TCHAR* argv[])
144 {    
145     
146     CMindryBuffer mindBuf;
147 
148     int iReadLenth;
149     char buf[100];
150     mindBuf.Write("abcd",4);
151     
152     iReadLenth = mindBuf.Read(buf,1);
153     buf[iReadLenth] = 0;
154     cout<<buf<<endl;
155 
156     mindBuf.Write("efghi",5);
157     iReadLenth = mindBuf.Read(buf,5);
158     buf[iReadLenth] = 0;
159     cout<<buf<<endl;
160 
161     mindBuf.Write("gklmn",5);
162     iReadLenth = mindBuf.Read(buf,8);
163     buf[iReadLenth] = 0;
164     cout<<buf<<endl;
165     
166 
167     return 0;
168 }