🚀 go-pugleaf

In article <1516@wiley.UUCP>, Bob Amstadt asks how to read the shift,
control, and alt keys.

Here is a fragment from a much larger program that shows how you
can get this information.  I have no idea how to do this using
the evnt_...(); routines.

Martin Minow
decvax!minow

The following software is in the public domain.  It is incomplete
as it stands and intended only as an illustration.

/*
 * The keytable structure is is returned by Keytbl().  It "points"
 * to the keyboard translation tables in the operating system.
 */

typedef struct {
    char	*unshifted;
    char	*shifted;
    char	*capslock;
} KEYTBL;

#define RIGHTSHIFT	0x01
#define	LEFTSHIFT	0x02
#define CTRLSHIFT	0x04
#define	ALTSHIFT	0x08
#define	CAPSSHIFT	0x10

KEYTBL		*keytbl;

main()
{
	...
	keytbl = Keytbl(-1L, -1L, -1L);	/* keyboard translation table	*/
	...
}
int
read_keyboard()
{
	register long	rawkey;
	register int	scancode;
	register int	c;			/* Translated key code	*/
	register int	shift;

	rawkey = Bconin(2);			/* Get char from kb:	*/
	scancode = (rawkey >> 16) & 0xFF;	/* Raw keyboard code.	*/
	shift = Getshift(-1);			/* Need the ALT key	*/
	if (scancode >= 0x78
	 && scancode <= 0x83)			/* Normalize strange	*/
	    scancode -= (0x78 - 0x02);		/* "ALT" + digit	*/
	if ((c = rawkey & 0xFF) == 0) {		/* ALT compose?		*/
	    if ((shift & (RIGHTSHIFT | LEFTSHIFT)) != 0)
		c = keytbl->shifted[scancode];
	    else if ((shift & CAPSSHIFT) != 0)
		c = keytbl->capslock[scancode];
	    else {
		c = keytbl->unshifted[scancode];
	    }
	    if ((shift & CTRLSHIFT) != 0)
		c &= 0x1F;
	}
	return (c);
}