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Better setting of terminal 'raw' mode, cribbed from BSD curses.
We no longer try to put the terminal into 8bit, no parity mode and
instead use the TCSASOFT flag to tcsetattr() as per the discussion
of this in lib/libocurses/tty.c.

/*
 * POSIX terminal I/O.
 *
 * The functions in this file
 * negotiate with the operating system for
 * keyboard characters, and write characters to
 * the display in a barely buffered fashion.
 */
#include	"def.h"

#include	<sys/types.h>
#include	<sys/time.h>
#include	<sys/ioctl.h>
#include	<fcntl.h>
#include	<termios.h>
#include	<term.h>

#define	NOBUF	512			/* Output buffer size.		*/

char	obuf[NOBUF];			/* Output buffer.		*/
int	nobuf;				/* buffer count			*/

static struct termios	ot;		/* entry state of the terminal	*/
static struct termios	nt;		/* editor's terminal state	*/

static int ttyactivep = FALSE;		/* terminal in editor mode?	*/
static int ttysavedp = FALSE;		/* terminal state saved?	*/

int	nrow;				/* Terminal size, rows.		*/
int	ncol;				/* Terminal size, columns.	*/

/*
 * This function gets called once, to set up
 * the terminal channel.  This version turns off flow
 * control.  This may be wrong for your system, but no
 * good solution has really been found (daveb).
 */
ttopen()
{
	register char	*cp;

	if (ttyactivep)
		return;

	if( !ttysavedp )
	{
		if (tcgetattr(0, &ot) < 0)
			abort();
		nt = ot;		/* save entry state		*/
		/* Set terminal to 'raw' mode and ignore a 'break' */
		nt.c_cc[VMIN] = 1;
		nt.c_cc[VTIME] = 0;
		nt.c_iflag |= IGNBRK;
		nt.c_iflag &= ~(BRKINT|PARMRK|INLCR|IGNCR|ICRNL|IXON);
		nt.c_oflag &= ~OPOST;
		nt.c_lflag &= ~(ECHO|ECHONL|ICANON|ISIG|IEXTEN);

		ttysavedp = TRUE;
	}
	
	if (tcsetattr(0, TCSASOFT | TCSADRAIN, &nt) < 0)
		abort();

	ttyactivep = TRUE;
}

/*
 * This function gets called just
 * before we go back home to the shell. Put all of
 * the terminal parameters back.
 */
ttclose()
{
	if(!ttysavedp || !ttyactivep)
		return;
	ttflush();
	if (tcsetattr(0, TCSASOFT | TCSADRAIN, &ot) < 0)
		abort();
	ttyactivep = FALSE;
}

/*
 * Write character to the display.
 * Characters are buffered up, to make things
 * a little bit more efficient.
 */
ttputc(c)
{

	if (nobuf >= NOBUF)
		ttflush();
	obuf[nobuf++] = c;
}

/*
 * Flush output.
 */
ttflush()
{

	if (nobuf != 0) {
		write(1, obuf, nobuf);
		nobuf = 0;
	}
}

/*
 * Read character from terminal.
 * All 8 bits are returned, so that you can use
 * a multi-national terminal.
 *
 * If keyboard 'queue' already has typeahead from a typeahead() call,
 * just return it.  Otherwise, make sure we are in blocking i/o mode
 * and read a character.
 */
ttgetc()
{
	int    c;

	while (read(0, &c, 1) != 1)
		;
	return (c & 0xFF);
}

/*
 * Return TRUE if there are characters waiting to be read.
 */
typeahead()
{
	int x;

	return((ioctl(0, FIONREAD, (char *) &x) < 0) ? 0 : x);
}


/*
 * panic:  print error and die, leaving core file.
 * Don't know why this is needed (daveb).
 */
panic(s)
char *s;
{

	(void) fputs("panic: ", stderr);
	(void) fputs(s, stderr);
	(void) fputc('\n', stderr);
	abort();		/* To leave a core image. */
}


/*
** This should check the size of the window, and reset if needed.
*/

setttysize()
{
#ifdef	TIOCGWINSZ
        struct winsize winsize;

	if (ioctl(0, TIOCGWINSZ, (char *) &winsize) == 0) {
		nrow = winsize.ws_row;
		ncol = winsize.ws_col;
	} else
#endif
	if ((nrow = lines) <= 0 || (ncol = columns) <= 0) {
		nrow = 24;
		ncol = 80;
	}

	/* Enforce maximum screen size. */
	if (nrow > NROW)
		nrow = NROW;
	if (ncol > NCOL)
		ncol = NCOL;
}

#ifndef NO_DPROMPT
/*
 * Return TRUE if we wait without doing anything, else return FALSE.
 */
ttwait()
{
	fd_set readfds;
	struct timeval tmout;

	FD_ZERO(&readfds);
	FD_SET(0, &readfds);

	tmout.tv_sec = 2;
	tmout.tv_usec = 0;

	if ((select(1, &readfds, NULL, NULL, &tmout)) == 0)
		return(TRUE);
	return(FALSE);
}
#endif NO_DPROMPT