showtty.c

unix linux 编程实践源代码

/* showtty.c
 *	displays some current tty settings
 */

#include	<stdio.h>
#include	<termios.h>

main()
{
	struct	termios ttyinfo;	/* this struct holds tty info */
						
	if ( tcgetattr( 0 , &ttyinfo ) == -1 ){   /* get info */
		perror( "cannot get params about stdin");
		exit(1);
	}
						/* show info */
	showbaud ( cfgetospeed( &ttyinfo ) );	/* get + show baud rate	*/
	printf("The erase character is ascii %d, Ctrl-%c\n",
			ttyinfo.c_cc[VERASE], ttyinfo.c_cc[VERASE]-1+'A');
	printf("The line kill character is ascii %d, Ctrl-%c\n",
			ttyinfo.c_cc[VKILL], ttyinfo.c_cc[VKILL]-1+'A');

	show_some_flags( &ttyinfo );		/* show misc. flags	*/
}

showbaud( int thespeed )
/*
 *	prints the speed in english
 */
{
	printf("the baud rate is ");
	switch ( thespeed ){
		case B300:	printf("300\n");	break;
		case B600:	printf("600\n"); 	break;
		case B1200:	printf("1200\n"); 	break;
		case B1800:	printf("1800\n"); 	break;
		case B2400:	printf("2400\n"); 	break;
		case B4800:	printf("4800\n"); 	break;
		case B9600:	printf("9600\n"); 	break;
		default:	printf("Fast\n");	break;
	}
}

struct flaginfo { int	fl_value; char	*fl_name; };

struct flaginfo input_flags[] = {

		IGNBRK	,	"Ignore break condition",
		BRKINT	,	"Signal interrupt on break",
		IGNPAR	,	"Ignore chars with parity errors",
		PARMRK	,	"Mark parity errors",
		INPCK	,	"Enable input parity check",
		ISTRIP	,	"Strip character",
		INLCR	,	"Map NL to CR on input",
		IGNCR	,	"Ignore CR",
		ICRNL	,	"Map CR to NL on input",
		IXON	,	"Enable start/stop output control",
		/* _IXANY  ,	"enable any char to restart output",	*/
		IXOFF   ,	"Enable start/stop input control",
		0	,	NULL };

struct flaginfo local_flags[] = {
		ISIG	,	"Enable signals",
		ICANON	,	"Canonical input (erase and kill)",
		/* _XCASE	,	"Canonical upper/lower appearance", */
		ECHO	,	"Enable echo",
		ECHOE	,	"Echo ERASE as BS-SPACE-BS",
		ECHOK	,	"Echo KILL by starting new line",
		0	,	NULL };

show_some_flags( struct termios *ttyp )
/*
 *	show the values of two of the flag sets_: c_iflag and c_lflag
 *	adding c_oflag and c_cflag is pretty routine - just add new
 *	tables above and a bit more code below.
 */
{
	show_flagset( ttyp->c_iflag, input_flags );
	show_flagset( ttyp->c_lflag, local_flags );
}

show_flagset( int thevalue, struct flaginfo thebitnames[] )
/*
 * check each bit pattern and display descriptive title
 */
{
	int	i;
	
	for ( i=0; thebitnames[i].fl_value ; i++ ) {
		printf( "  %s is ", thebitnames[i].fl_name);
		if ( thevalue & thebitnames[i].fl_value )
			printf("ON\n");
		else
			printf("OFF\n");
	}
}