freebsd-src/sys/ddb/db_output.c

/*
 * Mach Operating System
 * Copyright (c) 1991,1990 Carnegie Mellon University
 * All Rights Reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 *
 *	$Id: db_output.c,v 1.16 1996/01/15 22:39:35 phk Exp $
 */

/*
 * 	Author: David B. Golub, Carnegie Mellon University
 *	Date:	7/90
 */

/*
 * Printf and character output for debugger.
 */

#include <sys/param.h>
#include <sys/systm.h>

#include <machine/cons.h>
#include <machine/stdarg.h>

#include <ddb/ddb.h>
#include <ddb/db_output.h>

/*
 *	Character output - tracks position in line.
 *	To do this correctly, we should know how wide
 *	the output device is - then we could zero
 *	the line position when the output device wraps
 *	around to the start of the next line.
 *
 *	Instead, we count the number of spaces printed
 *	since the last printing character so that we
 *	don't print trailing spaces.  This avoids most
 *	of the wraparounds.
 */
static int	db_output_position = 0;		/* output column */
static int	db_last_non_space = 0;		/* last non-space character */
int	db_tab_stop_width = 8;		/* how wide are tab stops? */
#define	NEXT_TAB(i) \
	((((i) + db_tab_stop_width) / db_tab_stop_width) * db_tab_stop_width)
int	db_max_width = 80;		/* output line width */

/*
 * Force pending whitespace.
 */
void
db_force_whitespace()
{
	register int last_print, next_tab;

	last_print = db_last_non_space;
	while (last_print < db_output_position) {
	    next_tab = NEXT_TAB(last_print);
	    if (next_tab <= db_output_position) {
		while (last_print < next_tab) { /* DON'T send a tab!!! */
			cnputc(' ');
			last_print++;
		}
	    }
	    else {
		cnputc(' ');
		last_print++;
	    }
	}
	db_last_non_space = db_output_position;
}

/*
 * Output character.  Buffer whitespace.
 */
void
db_putchar(c)
	int	c;		/* character to output */
{
	if (c > ' ' && c <= '~') {
	    /*
	     * Printing character.
	     * If we have spaces to print, print them first.
	     * Use tabs if possible.
	     */
	    db_force_whitespace();
	    cnputc(c);
	    db_output_position++;
	    db_last_non_space = db_output_position;
	}
	else if (c == '\n') {
	    /* Newline */
	    cnputc(c);
	    db_output_position = 0;
	    db_last_non_space = 0;
	    db_check_interrupt();
	}
	else if (c == '\r') {
	    /* Return */
	    cnputc(c);
	    db_output_position = 0;
	    db_last_non_space = 0;
	    db_check_interrupt();
	}
	else if (c == '\t') {
	    /* assume tabs every 8 positions */
	    db_output_position = NEXT_TAB(db_output_position);
	}
	else if (c == ' ') {
	    /* space */
	    db_output_position++;
	}
	else if (c == '\007') {
	    /* bell */
	    cnputc(c);
	}
	/* other characters are assumed non-printing */
}

/*
 * Return output position
 */
int
db_print_position()
{
	return (db_output_position);
}

/*
 * Printing
 */
void
db_printf(const char *fmt, ...)
{
	va_list	listp;
	va_start(listp, fmt);
	kvprintf (fmt, db_putchar, NULL, db_radix, listp);
	va_end(listp);
}

/*
 * End line if too long.
 */
void
db_end_line()
{
	if (db_output_position >= db_max_width)
	    db_printf("\n");
}