xref: /netbsd-src/usr.bin/vis/foldit.c (revision ce63d6c20fc4ec8ddc95c84bb229e3c4ecf82b69)
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[] = "@(#)foldit.c	5.1 (Berkeley) 4/18/91";
36 #endif /* not lint */
37 
38 foldit(chunk, col, max)
39 	char *chunk;
40 {
41 	register char *cp;
42 
43 	/*
44 	 * Keep track of column position. Insert hidden newline
45 	 * if this chunk puts us over the limit.
46 	 */
47 again:
48 	cp = chunk;
49 	while (*cp) {
50 		switch(*cp) {
51 		case '\n':
52 		case '\r':
53 			col = 0;
54 			break;
55 		case '\t':
56 			col = col + 8 &~ 07;
57 			break;
58 		case '\b':
59 			col = col ? col - 1 : 0;
60 			break;
61 		default:
62 			col++;
63 		}
64 		if (col > (max - 2)) {
65 			printf("\\\n");
66 			col = 0;
67 			goto again;
68 		}
69 		cp++;
70 	}
71 	return (col);
72 }
73