Flying Characters as Screen Saver using C program

/*C program to design flying characters Screen Saver.*/

 

#include <stdio.h>

#include <termios.h>

#include <unistd.h>

#include <fcntl.h>

 

/*will return character based on passed number*/

char getCHAR(int n)

{

    char ok[]="~!@#$%^&*:;'\",{}|<>=";

    return ok[n];

}

 

/*function to identify that any key hit by the keyboard*/

int kbhit(void)

{

  struct termios oldt, newt;

  int ch;

  int oldf;

  

  tcgetattr(STDIN_FILENO, &oldt);

  newt = oldt;

  newt.c_lflag &= ~(ICANON | ECHO);

  tcsetattr(STDIN_FILENO, TCSANOW, &newt);

  oldf = fcntl(STDIN_FILENO, F_GETFL, 0);

  fcntl(STDIN_FILENO, F_SETFL, oldf | O_NONBLOCK);

  

  ch = getchar();

  

  tcsetattr(STDIN_FILENO, TCSANOW, &oldt);

  fcntl(STDIN_FILENO, F_SETFL, oldf);

  

  if(ch != EOF)

  {

    ungetc(ch, stdin);

    return 1;

  }

  

  return 0;

}

  

/*move cursor on specified position on screen*/

void gotoxy(int x,int y)

{

printf("%c[%d;%df",0x1B,y,x);

}

 

int main(void) {

    int x,y;

    long int i,j;

    i=j=0;

 

    x=1; y=20;

    system("clear");

 

    /*program will run until any key hit*/

    while(!kbhit())

    {

        x=rand()%((150-1+1)+1);

        y=rand()%((50-1+1)+1);

        gotoxy(x,y);

        printf("%c", getCHAR(rand()%((20-1+1)+1))); fflush(stdout);

        ++i;

        if(i==10000) {++j; i=0;}

        if(j==100000){ i=0;}

        if(j<=100)

            usleep(30000);

        if(j<=1000)

            usleep(3000);

        if(j<=10000)

            usleep(300);

    }

    return 0;

}