双缓冲的誉抄的过程

程序一利用双缓冲、三线程的串行执行实现从输入文件到屏幕的拷贝输出：

代码如下：

#include<windows.h>
#include<iostream>
using namespacestd;
FILE *infile;
char buf1,buf2;
void get(){buf1=fgetc(infile);}
void copy(){buf2=buf1;}
void put( ){putchar(buf2);}
int main()
{
      infile=fopen("in.txt","r");
for(;buf1!=EOF;)
      {
           get();
           copy();
           put();
      }
fclose(infile);
return 0;
}

程序二实现线程的随机并发执行：

代码如下：
#include <cstdio>
#include "conio.h"
#include "windows.h"
#include <iostream>
using namespace std;
typedef struct _THREADDATA
{
      FILE*infile;
      char*buf1;
      char*buf2;
}*LPTHREADDATA, THREADDATA;
DWORD WINAPI get(LPVOID lParam)
{
   LPTHREADDATA pData = (LPTHREADDATA)lParam;
for (;*pData->buf1!=EOF;)
      {
           *pData->buf1=fgetc(pData->infile);    
           Sleep(1);
      }
 return 0;
}
DWORD WINAPI copy(LPVOID lParam)
{
LPTHREADDATA pData = (LPTHREADDATA)lParam;
for (;*pData->buf1!=EOF;)
      *pData->buf2=*pData->buf1;
      return0;
}
DWORD WINAPI put(LPVOID lParam)
{
   LPTHREADDATA pData = (LPTHREADDATA)lParam;
for (;*pData->buf1!=EOF;)
      {
           cout<<*pData->buf2<<endl;
           Sleep(1);
      }
return 0;
}
int main()
{
      FILE*infile=fopen("in.txt","r");
      charbuf1,buf2;
   LPTHREADDATA pData = new THREADDATA;
      pData->infile=infile;
      pData->buf1=&buf1;
      pData->buf2=&buf2;;
DWORD ThreadId1,ThreadId2,ThreadId3;
      ::CreateThread(NULL,0, get, (LPVOID)pData, 0, &ThreadId1);    

      ::CreateThread(NULL,0, copy, (LPVOID)pData, 0, &ThreadId2); 

      ::CreateThread(NULL,0, put, (LPVOID)pData, 0, &ThreadId3);      

getch();
      fclose(infile);
return0;
}

程序三控制进程实现正确的并发誊抄：

代码如下：

#include <cstdio>
#include "conio.h"
#include "windows.h"
#include <iostream>
using namespace std;
HANDLE Mutex;
HANDLE buf1_e;
HANDLE buf1_f;
HANDLE buf2_e;
HANDLE buf2_f;
typedef struct _THREADDATA
{
      FILE*infile;
      char*buf1;
      char*buf2;
}*LPTHREADDATA, THREADDATA;
DWORD WINAPI get(LPVOID lParam)
{
      LPTHREADDATApData = (LPTHREADDATA)lParam;
for (;*pData->buf1!=EOF;)
      {
           WaitForSingleObject(buf1_e,INFINITE);
           *pData->buf1=fgetc(pData->infile);    
           ReleaseSemaphore(buf1_f,1,NULL);
      }
 return 0;
}
 
DWORD WINAPI copy(LPVOID lParam)
{
      LPTHREADDATApData = (LPTHREADDATA)lParam;
for (;*pData->buf1!=EOF;)
      {
           WaitForSingleObject(buf1_f,INFINITE);
           WaitForSingleObject(buf2_e,INFINITE);
           *pData->buf2=*pData->buf1;
           ReleaseSemaphore(buf1_e,1,NULL);
           ReleaseSemaphore(buf2_f,1,NULL);
      }
return 0;
}
DWORD WINAPI put(LPVOID lParam)
{
      LPTHREADDATApData = (LPTHREADDATA)lParam;
for (;*pData->buf1!=EOF;)
      {
           WaitForSingleObject(buf2_f,INFINITE);
           cout<<*pData->buf2;
           ReleaseSemaphore(buf2_e,1,NULL);
      }
return 0;
}
int main()
{
 //  Mutex=CreateMutex(NULL,FALSE,NULL);  
      buf1_e=CreateSemaphore(NULL,1,1,NULL);
      buf1_f=CreateSemaphore(NULL,0,1,NULL);
      buf2_e=CreateSemaphore(NULL,1,1,NULL);
      buf2_f=CreateSemaphore(NULL,0,1,NULL);
      FILE*infile=fopen("in.txt","r");
      charbuf1,buf2;
   LPTHREADDATA pData = new THREADDATA;
      pData->infile=infile;
      pData->buf1=&buf1;
      pData->buf2=&buf2;
   DWORDThreadId1,ThreadId2,ThreadId3;
      ::CreateThread(NULL,0, copy, (LPVOID)pData, 0, &ThreadId2); 

      ::CreateThread(NULL,0, put, (LPVOID)pData, 0, &ThreadId3);      

      ::CreateThread(NULL,0, get, (LPVOID)pData, 0, &ThreadId1);    

getch();
      fclose(infile);
   return 0;
}