main.c

对函数select()的测试

#include <unistd.h>
#include <time.h>
#include <sys/time.h>
#include <math.h>
#include <stdio.h>      /*fputs()*/
#include <stdlib.h>     /*exit()*/
#include <string.h>    	/*memset(),atoi()*/
#include <errno.h>      /*strerror()*/
#include <netinet/in.h> /*struct sockaddr_in,htons(),inet_addr()*/
#include <sys/types.h>  /*socket()*/
#include <sys/socket.h> /*socket(),inet_addr()*/
#include <fcntl.h>
#include "main.h"
int main()
{
  fd_set  readfds;
  struct  timeval tv;    //tv是记时器，可以精确到微秒
  int     maxfd,nfds=0;
  int     pid0 = -1,pid1 = -1;
  int     fdkeypipe = -1;
  int     ikeycode = 0;
  int     combuf[512]={0};
  int     iReadNum = 0;
  //打开键盘管道，作为main和keyfunc交换数据的通道
  fdkeypipe = open("/dev/keypipe",O_RDWR);
  if (fdkeypipe<0)
  {
    printf("open keypipe fail!\n");
    exit(1);
  }
  gfdcom = open("/dev/uart0",O_RDWR | O_NOCTTY | O_NDELAY);
  if (gfdcom < 0)
  {
    close(fdkeypipe);
    printf("open com fail!\n");
    exit(1);
  }
  //创建进程1执行读键盘程序
  pid1 = vfork();
  if(pid1==0){
	printf("ok\n");
	execl("/bin/keyfunc","/bin/keyfunc",(char *)0);
	perror("fork call err\n");
  }
  else if (pid1 < 0)
  {
    printf("Creat fork1 fail!\n");
    exit(1);
  }
  printf("Start ...\n");
  for(;;)
  {
    tv.tv_usec = 0;
    tv.tv_sec=5;
    FD_ZERO(&readfds);
	maxfd = 0;
	FD_SET(fdkeypipe,&readfds);
	//FD_SET(gfdsock_sr, &readfds); //fd1是句柄，可以是串口，网口，管道等
	FD_SET(gfdcom, &readfds); //fd1是句柄，可以是串口，网口，管道等
	//maxfd = max(gfdsock_sr, maxfd);    
	maxfd = max(fdkeypipe, maxfd);
	maxfd = max(gfdcom,maxfd);
	nfds = select(maxfd+1, &readfds, NULL, NULL, &tv);
	if(FD_ISSET(fdkeypipe, &readfds)) 
	{
	    read(fdkeypipe,&ikeycode,sizeof(ikeycode));
	    printf("main ikeycode = %d\n",ikeycode);
	}
	if(FD_ISSET(gfdcom, &readfds)) 
	{
	    printf("receive com\n");
	    iReadNum = read(gfdcom,combuf,sizeof(combuf));
	    write(gfdcom,combuf,iReadNum);
	}
  }
  close(fdkeypipe);
  close(gfdcom);
  return 0;
}
int max(int num0,int num1)
{
  if (num0 > num1 )
  {
     return num0;
  }
  else
  {
     return num1;
  }
}