xref: /dragonfly/usr.bin/vis/foldit.c (revision dc71b7ab)
1 /*-
2  * Copyright (c) 1990, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  * @(#)foldit.c	8.1 (Berkeley) 6/6/93
30  * $FreeBSD: src/usr.bin/vis/foldit.c,v 1.4 1999/08/28 01:07:25 peter Exp $
31  * $DragonFly: src/usr.bin/vis/foldit.c,v 1.4 2008/10/16 01:52:34 swildner Exp $
32  */
33 
34 #include <stdio.h>
35 
36 int
37 foldit(char *chunk, int col, int max)
38 {
39 	char *cp;
40 
41 	/*
42 	 * Keep track of column position. Insert hidden newline
43 	 * if this chunk puts us over the limit.
44 	 */
45 again:
46 	cp = chunk;
47 	while (*cp) {
48 		switch(*cp) {
49 		case '\n':
50 		case '\r':
51 			col = 0;
52 			break;
53 		case '\t':
54 			col = col + 8 &~ 07;
55 			break;
56 		case '\b':
57 			col = col ? col - 1 : 0;
58 			break;
59 		default:
60 			col++;
61 		}
62 		if (col > (max - 2)) {
63 			printf("\\\n");
64 			col = 0;
65 			goto again;
66 		}
67 		cp++;
68 	}
69 	return (col);
70 }
71