.................bug

//  fifo.cpp : 定义控制台应用程序的入口点。
//

#include  " stdafx.h "

#include  < windows.h >



#define  BUF_MAX 1024
#define  LIST_MAX  4

struct  LIST
{
     volatile   int  head;
     volatile   int  tail;
     volatile   int  empty;
     volatile   int  full;
    
    size_t size[LIST_MAX];
     char *  buff;
};


struct  LIST swreg;

HANDLE hWrite;
HANDLE hRead;


void  wait_write()
{
    printf( " %s\n " ,__FUNCTION__);
    ::WaitForSingleObject(hWrite,INFINITE);
}
void  wait_read()
{
    printf( " %s\n " ,__FUNCTION__);

    ::WaitForSingleObject(hRead,INFINITE);
}
void  signel_write()
{
    printf( " %s\n " ,__FUNCTION__);
    SetEvent(hWrite);
}
void  signel_read()
{
    printf( " %s\n " ,__FUNCTION__);
    SetEvent(hRead);

}



size_t writedata( char *  bufptr,size_t bufcnt)
{
     int  head;
     int  empty;
    size_t count;

     if (bufcnt > BUF_MAX)
         return   - 1 ;
        
        
     if (swreg.full == 1 )
    {
         while ( 1 )
        {
            wait_write();
             if (swreg.full == 0 )
                 break ;
        }
    }    
    
    
    head = swreg.head;
    
    count = bufcnt;
    memcpy(swreg.buff + head * BUF_MAX,bufptr,count);
    swreg.size[head] = count;    
    
    
    head = (head + 1 ) % LIST_MAX;
     if (head == swreg.tail)
        swreg.full = 1 ;

    
    empty = swreg.empty;
     // 如果此时线程切换，程序死锁~ 在多CPU，采用共享内存和互相中断方式通讯中出现问题。还好，我只要外部加超时机制即可以避免问题。

    ::Sleep( 1 );
    swreg.empty = 0 ;
    swreg.head = head;
    
     if (empty)
        signel_read();



     return  bufcnt;
    
}



size_t readdata( char *  bufptr,size_t bufcnt)
{

     int  full;
     int  tail;

    size_t count;
     if (swreg.empty == 1 )
    {
         while ( 1 )
        {
            wait_read();
             if (swreg.empty == 0 )
                 break ;
        }
    }

    tail = swreg.tail;
    memcpy(bufptr,swreg.buff + tail * BUF_MAX,swreg.size[tail]);
    count = swreg.size[tail];



    tail = (tail + 1 ) % LIST_MAX;
     if (swreg.head == tail)
        swreg.empty = 1 ;

    swreg.tail = tail;
    full = swreg.full;
    swreg.full = 0 ;  
     if (full)
        signel_write();
        

     return  count;
}


DWORD WINAPI thread_write(LPVOID p)
{
     int  i = 0 ;
     char   *  sz[] =
    {
         " sz0-1 " ,
         " sz1-12 " ,
         " sz2-123 " ,
         " sz3-12345 " ,
         " sz4-123456 " ,
         " sz5-1234567 " ,
         " sz6-12345678 " ,
         " sz7-123456789 " ,
         " sz8-1234567890 " ,
         " sz9-1234567890a " ,
    };
     while ( 1 )
    {
         if (i == sizeof (sz) / sizeof (sz[ 0 ]))
            i = 0 ;
        writedata(sz[i],strlen(sz[i]) + 1  );

        i ++ ;        
    }
     return   0 ;
}

DWORD WINAPI thread_read(LPVOID p)
{
     int  i = 0 ;
     char  sz[BUF_MAX];
     while ( 1 )
    {
        size_t s = readdata(sz,BUF_MAX );
        printf( " %d:%s,length(%d)\n " ,i ++ ,sz,s);
        
    }

     return   0 ;
}



int  _tmain( int  argc, _TCHAR *  argv[])
{

     char   *  buf = new   char [LIST_MAX * BUF_MAX];


    hWrite = CreateEvent( 0 , 0 , 0 , 0 );
    hRead = CreateEvent( 0 , 0 , 0 , 0 );




     if (buf)
    {
        memset( & swreg, 0 , sizeof (swreg) );
        swreg.buff = buf;
        swreg.empty = 1 ;


        DWORD ThreadId;

        CreateThread(NULL,NULL,thread_write,NULL,NULL, & ThreadId);
        CreateThread(NULL,NULL,thread_read,NULL,NULL, & ThreadId);



        
    }


     char  c = getchar();

     while (c != EOF)
    {
        c = getchar();
    }

    delete buf;

    CloseHandle(hWrite);
    CloseHandle(hRead);

    
     return   0 ;
}