xref: /openbsd/usr.bin/vis/foldit.c (revision fc61954a)
1 /*	$OpenBSD: foldit.c,v 1.7 2013/11/12 22:51:18 deraadt Exp $	*/
2 /*	$NetBSD: foldit.c,v 1.4 1994/12/20 16:13:02 jtc Exp $	*/
3 
4 /*-
5  * Copyright (c) 1990, 1993
6  *	The Regents of the University of California.  All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 #include <stdio.h>
34 
35 int	foldit(char *chunk, int col, int max);
36 
37 int
38 foldit(char *chunk, int col, int max)
39 {
40 	char *cp;
41 
42 	/*
43 	 * Keep track of column position. Insert hidden newline
44 	 * if this chunk puts us over the limit.
45 	 */
46 again:
47 	cp = chunk;
48 	while (*cp) {
49 		switch(*cp) {
50 		case '\n':
51 		case '\r':
52 			col = 0;
53 			break;
54 		case '\t':
55 			col = (col + 8) & ~07;
56 			break;
57 		case '\b':
58 			col = col ? col - 1 : 0;
59 			break;
60 		default:
61 			col++;
62 		}
63 		if (col > (max - 2)) {
64 			printf("\\\n");
65 			col = 0;
66 			goto again;
67 		}
68 		cp++;
69 	}
70 	return (col);
71 }
72