c - 替换 read(int fd, void *buf, size_t count); Linux 中的晶圆？

Question

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <linux/input.h>

#define MOUSEFILE "/dev/input/mice"

int old_x=0,old_y=0;
char x,y;
int change(int X,int Y)
{
if(old_x==X&&old_y==Y)
{

    printf("Mouse is Still \n ");
}
else
{   

    old_x=X;
    old_y=Y;
    printf("Mouse is Moving \n");   
}

}
int main()
{
int fd;
struct input_event ie;
unsigned char button,bLeft,bMiddle,bRight;
int Mouse_status=0;
int absolute_x=0,absolute_y=0;

if((fd = open(MOUSEFILE, O_RDONLY)) == -1) 
{
    printf("Device open ERROR\n");
    exit(EXIT_FAILURE);
}
else
{
    printf("Device open OK\n");
}
printf("right-click to set absolute x,y coordinates origin (0,0)\n");
while(1)
{   

    read(fd, &ie, sizeof(struct input_event));
    unsigned char *ptr = (unsigned char*)&ie;      
    button=ptr[0];
    bLeft = button & 0x1;
    bMiddle = ( button & 0x4 ) ;
    bRight = ( button & 0x2 ) ;
    x=(char) ptr[1];y=(char) ptr[2];

    system("clear");
    change(x,y);
    if(bLeft)
    {
        printf("bLEFT  bMIDDLE  bRIGHT  \n ");
        printf("DOWN   UP       UP      \n ");
    }
    else if(bMiddle)
    {
        printf("bLEFT  bMIDDLE  bRIGHT  \n ");
        printf("UP     DOWN     UP      \n ");
    }
    else if(bRight)
    {
        printf("bLEFT  bMIDDLE  bRIGHT  \n ");
        printf("UP     UP       DOWN    \n ");
    }       
    else if(bLeft==0&&bMiddle==0&&bRight==0)
    {               
        printf("bLEFT  bMIDDLE  bRIGHT  \n ");
        printf("UP     UP       UP      \n ");
    }
    absolute_x+=x;
    absolute_y-=y;

    printf("Absolute coords from TOP_LEFT= %d %d\n",absolute_x,absolute_y);
    //printf("OLD_X %d and OLD_Y %d \n",old_x,old_y);
    //printf("X is %d ,Y is %d \n",x,y);
    // comment to disable the display of raw event structure datas
    //
    //for(i=0; i<sizeof(ie); i++)
   // {
   //     printf("%02X ", *ptr++);
   // }

  }
close(fd);
return 0;
}

在上面的程序中，我使用了 read wafer，这是一个阻塞调用(它会等到我给出一些输入值)。是否有任何其他函数可以执行与 read wafer 相同的操作，不应阻塞.

Answer 1

你可以简单的设置为非阻塞

int flags = fcntl(fd, F_GETFL, 0); 
fcntl(fd, F_SETFL, flags | O_NONBLOCK);

看看this例如，供引用。