.................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;
}