xref: /netbsd-src/usr.bin/vis/foldit.c (revision 5f7096188587a2c7c95fa3c69b78e1ec9c7923d0)
1 /*-
2  * Copyright (c) 1990 The Regents of the University of California.
3  * 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. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #ifndef lint
35 /*static char sccsid[] = "from: @(#)foldit.c	5.1 (Berkeley) 4/18/91";*/
36 static char rcsid[] = "$Id: foldit.c,v 1.2 1993/08/01 18:04:01 mycroft Exp $";
37 #endif /* not lint */
38 
39 foldit(chunk, col, max)
40 	char *chunk;
41 {
42 	register char *cp;
43 
44 	/*
45 	 * Keep track of column position. Insert hidden newline
46 	 * if this chunk puts us over the limit.
47 	 */
48 again:
49 	cp = chunk;
50 	while (*cp) {
51 		switch(*cp) {
52 		case '\n':
53 		case '\r':
54 			col = 0;
55 			break;
56 		case '\t':
57 			col = col + 8 &~ 07;
58 			break;
59 		case '\b':
60 			col = col ? col - 1 : 0;
61 			break;
62 		default:
63 			col++;
64 		}
65 		if (col > (max - 2)) {
66 			printf("\\\n");
67 			col = 0;
68 			goto again;
69 		}
70 		cp++;
71 	}
72 	return (col);
73 }
74