C++版的迴圈緩衝區類（實際測試可用！）

/* * CCycleBuffer.h * *  Created on: 2013-5-27 *      Author: shiguang */#ifndef __test__CCycleBuffer__#define __test__CCycleBuffer__#include <stdio.h>#include <stdlib.h>#include <string.h>#include <assert.h>class CCycleBuffer{public:bool isFull();bool isEmpty();void Empty();int GetLength();CCycleBuffer(int size);virtual ~CCycleBuffer();int Write(char* buf, int count);int Read(char* buf, int count);private:bool m_bEmpty, m_bFull;char * m_pBuf;int m_nBufSize;int m_nReadPos;int m_nWritePos;public:int GetReadPos(){return m_nReadPos;}int GetWritePos(){return m_nWritePos;}};#endif /* defined(__test__CCycleBuffer__) */

 

/* * CCycleBuffer.cpp * *  Created on: 2013-5-27 *      Author: shiguang */#include "CCycleBuffer.h"// 定義CCycleBuffer::CCycleBuffer(int size){m_nBufSize = size;m_nReadPos = 0;m_nWritePos = 0;m_pBuf = new char[m_nBufSize];m_bEmpty = true;m_bFull = false;}CCycleBuffer::~CCycleBuffer(){delete[] m_pBuf;}/************************************************************************//* 向緩衝區寫入資料，返回實際寫入的位元組數                               *//************************************************************************/int CCycleBuffer::Write(char* buf, int count){if (count <= 0)return 0;m_bEmpty = false;// 緩衝區已滿，不能繼續寫入if (m_bFull){return 0;}else if (m_nReadPos == m_nWritePos) // 緩衝區為空白時{/*                          == 記憶體模型 == (empty)             m_nReadPos                (empty) |----------------------------------|-----------------------------------------| m_nWritePos        m_nBufSize */int leftcount = m_nBufSize - m_nWritePos;if (leftcount > count){memcpy(m_pBuf + m_nWritePos, buf, count);m_nWritePos += count;m_bFull = (m_nWritePos == m_nReadPos);return count;}else{memcpy(m_pBuf + m_nWritePos, buf, leftcount);m_nWritePos =(m_nReadPos > count - leftcount) ?count - leftcount : m_nReadPos; // 計算未寫入資料大小memcpy(m_pBuf, buf + leftcount, m_nWritePos);m_bFull = (m_nWritePos == m_nReadPos);return leftcount + m_nWritePos;}}else if (m_nReadPos < m_nWritePos) // 有剩餘空間可寫入{/*                           == 記憶體模型 == (empty)                 (data)                     (empty) |-------------------|----------------------------|---------------------------| m_nReadPos                m_nWritePos       (leftcount) */// 剩餘緩衝區大小(從寫入位置到緩衝區尾)int leftcount = m_nBufSize - m_nWritePos;if (leftcount > count)   // 有足夠的剩餘空間存放{memcpy(m_pBuf + m_nWritePos, buf, count);m_nWritePos += count;m_bFull = (m_nReadPos == m_nWritePos);assert(m_nReadPos <= m_nBufSize);assert(m_nWritePos <= m_nBufSize);return count;}else       // 剩餘空間不足{// 先填充滿剩餘空間，再回頭找空間存放memcpy(m_pBuf + m_nWritePos, buf, leftcount);m_nWritePos =(m_nReadPos >= count - leftcount) ?count - leftcount : m_nReadPos;memcpy(m_pBuf, buf + leftcount, m_nWritePos);m_bFull = (m_nReadPos == m_nWritePos);assert(m_nReadPos <= m_nBufSize);assert(m_nWritePos <= m_nBufSize);return leftcount + m_nWritePos;}}else{/*                          == 記憶體模型 == (unread)                 (read)                     (unread) |-------------------|----------------------------|---------------------------| m_nWritePos    (leftcount)    m_nReadPos */int leftcount = m_nReadPos - m_nWritePos;if (leftcount > count){// 有足夠的剩餘空間存放memcpy(m_pBuf + m_nWritePos, buf, count);m_nWritePos += count;m_bFull = (m_nReadPos == m_nWritePos);assert(m_nReadPos <= m_nBufSize);assert(m_nWritePos <= m_nBufSize);return count;}else{// 剩餘空間不足時要丟棄後面的資料memcpy(m_pBuf + m_nWritePos, buf, leftcount);m_nWritePos += leftcount;m_bFull = (m_nReadPos == m_nWritePos);assert(m_bFull);assert(m_nReadPos <= m_nBufSize);assert(m_nWritePos <= m_nBufSize);return leftcount;}}}/************************************************************************//* 從緩衝區讀資料，返回實際讀取的位元組數                                 *//************************************************************************/int CCycleBuffer::Read(char* buf, int count){if (count <= 0)return 0;m_bFull = false;if (m_bEmpty)       // 緩衝區空，不能繼續讀取資料{return 0;}else if (m_nReadPos == m_nWritePos)   // 緩衝區滿時{/*                          == 記憶體模型 == (data)          m_nReadPos                (data) |--------------------------------|--------------------------------------------| m_nWritePos         m_nBufSize */int leftcount = m_nBufSize - m_nReadPos;if (leftcount > count){memcpy(buf, m_pBuf + m_nReadPos, count);m_nReadPos += count;m_bEmpty = (m_nReadPos == m_nWritePos);return count;}else{memcpy(buf, m_pBuf + m_nReadPos, leftcount);m_nReadPos =(m_nWritePos > count - leftcount) ?count - leftcount : m_nWritePos;memcpy(buf + leftcount, m_pBuf, m_nReadPos);m_bEmpty = (m_nReadPos == m_nWritePos);return leftcount + m_nReadPos;}}else if (m_nReadPos < m_nWritePos)   // 寫指標在前(未讀資料是串連的){/*                          == 記憶體模型 == (read)                 (unread)                      (read) |-------------------|----------------------------|---------------------------| m_nReadPos                m_nWritePos                     m_nBufSize */int leftcount = m_nWritePos - m_nReadPos;int c = (leftcount > count) ? count : leftcount;memcpy(buf, m_pBuf + m_nReadPos, c);m_nReadPos += c;m_bEmpty = (m_nReadPos == m_nWritePos);assert(m_nReadPos <= m_nBufSize);assert(m_nWritePos <= m_nBufSize);return c;}else          // 讀指標在前(未讀資料可能是不串連的){/*                          == 記憶體模型 == (unread)                (read)                      (unread) |-------------------|----------------------------|---------------------------| m_nWritePos                  m_nReadPos                  m_nBufSize */int leftcount = m_nBufSize - m_nReadPos;if (leftcount > count)   // 未讀緩衝區夠大，直接讀取資料{memcpy(buf, m_pBuf + m_nReadPos, count);m_nReadPos += count;m_bEmpty = (m_nReadPos == m_nWritePos);assert(m_nReadPos <= m_nBufSize);assert(m_nWritePos <= m_nBufSize);return count;}else       // 未讀緩衝區不足，需回到緩衝區頭開始讀{memcpy(buf, m_pBuf + m_nReadPos, leftcount);m_nReadPos =(m_nWritePos >= count - leftcount) ?count - leftcount : m_nWritePos;  // 計算剩餘未讀資料大小memcpy(buf + leftcount, m_pBuf, m_nReadPos); // 注意目的指標位置m_bEmpty = (m_nReadPos == m_nWritePos);assert(m_nReadPos <= m_nBufSize);assert(m_nWritePos <= m_nBufSize);return leftcount + m_nReadPos;}}}/************************************************************************//* 擷取緩衝區有效資料長度                                               *//************************************************************************/int CCycleBuffer::GetLength(){if (m_bEmpty){return 0;}else if (m_bFull){return m_nBufSize;}else if (m_nReadPos < m_nWritePos){return m_nWritePos - m_nReadPos;}else{return m_nBufSize - m_nReadPos + m_nWritePos;}}void CCycleBuffer::Empty(){m_nReadPos = 0;m_nWritePos = 0;m_bEmpty = true;m_bFull = false;}bool CCycleBuffer::isEmpty(){return m_bEmpty;}bool CCycleBuffer::isFull(){return m_bFull;}

 

 

 

/* * main.cpp * *  Created on: 2013-5-27 *      Author: shiguang */#include "CCycleBuffer.h"int main(){CCycleBuffer buffer(100);char* datachar = new char[40];char* reschar = new char[100];int res = 0;for (int i = 0; i < 40; ++i){datachar[i] = i + 1;}res = buffer.Write(datachar, 40);printf("寫入資料個數：%d\n", res);res = buffer.Write(datachar, 40);printf("寫入資料個數：%d\n", res);res = buffer.Write(datachar, 40);printf("寫入資料個數：%d\n", res);res = buffer.Write(datachar, 40);printf("寫入資料個數：%d\n", res);res = buffer.Read(reschar, 100);printf("讀取資料個數：%d\n", res);for (int i = 0; i < 100; ++i){if (i % 10 == 0){printf("\n");}printf("%2d   ", reschar[i]);}return 0;}

輸出結果：

 

 

寫入資料個數：40寫入資料個數：40寫入資料個數：20寫入資料個數：0讀取資料個數：100 1    2    3    4    5    6    7    8    9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40    1    2    3    4    5    6    7    8    9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40    1    2    3    4    5    6    7    8    9   10   11   12   13   14   15   16   17   18   19   20   

來源程式來自網路資料！