/* bounce_aio.c *	purpose	animation with user control, using aio_read() etc *	note	set_ticker() sends SIGALRM, handler does animation *		keyboard sends SIGIO, main only calls pause() *	compile cc bounce_aio.c set_ticker.c -lrt  -lcurses -o bounce_aio */#include	<stdio.h>#include	<curses.h>#include	<signal.h>#include	<aio.h>/* The state of the game 			*/#define	MESSAGE	"hello"#define	BLANK	"     "int	row   = 10;	/* current row		*/int	col   =  0;	/* current column	*/int	dir   =  1;	/* where we are going	*/int	delay = 200;	/* how long to wait	*/int	done  = 0;struct aiocb kbcbuf;	/* an aio control buf   */main(){	void	on_alarm(int);	/* handler for alarm	*/	void	on_input(int);	/* handler for keybd    */	void	setup_aio_buffer();	initscr();		/* set up screen */	crmode();	noecho();	clear();	signal(SIGIO, on_input);          /* install a handler        */	setup_aio_buffer();	  	  /* initialize aio ctrl buff */	aio_read(&kbcbuf);		  /* place a read request     */	signal(SIGALRM, on_alarm);        /* install alarm handler    */	set_ticker(delay);		  /* start ticking	      */	mvaddstr( row, col, MESSAGE );    /* draw initial image       */	while( !done )			  /* the main loop */		pause();	endwin();}/* * handler called when aio_read() has stuff to read *   First check for any error codes, and if ok, then get the return code */void on_input(){	int  c;	char *cp = (char *) kbcbuf.aio_buf;	/* cast to char * */	/* check for errors */	if ( aio_error(&kbcbuf) != 0 )		perror("reading failed");	else 		/* get number of chars read */		if ( aio_return(&kbcbuf) == 1 )		{			c = *cp;			if ( c == 'Q' || c == EOF )				done = 1;			else if ( c == ' ' )				dir = -dir;		}	/* place a new request */	aio_read(&kbcbuf);}void on_alarm(){	signal(SIGALRM, on_alarm);	/* reset, just in case	*/	mvaddstr( row, col, BLANK );	/* clear old string	*/	col += dir;			/* move to new column	*/	mvaddstr( row, col, MESSAGE );	/* draw new string	*/	refresh();			/* and show it		*/	/*	 * now handle borders	 */	if ( dir == -1 && col <= 0 )		dir = 1;	else if ( dir == 1 && col+strlen(MESSAGE) >= COLS )		dir = -1;}/* * set members of struct.   *   First specify args like those for read(fd, buf, num)  and offset *   Then  specify what to do (send signal) and what signal (SIGIO) */void setup_aio_buffer(){	static char input[1];		      /* 1 char of input */	/* describe what to read */	kbcbuf.aio_fildes     = 0;	      /* standard intput */	kbcbuf.aio_buf        = input;	      /* buffer          */	kbcbuf.aio_nbytes     = 1;             /* number to read  */	kbcbuf.aio_offset     = 0;             /* offset in file  */	/* describe what to do when read is ready */	kbcbuf.aio_sigevent.sigev_notify = SIGEV_SIGNAL;	kbcbuf.aio_sigevent.sigev_signo  = SIGIO;  /* send sIGIO   */}