text_cmds/vis/foldit.c

   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. 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 #include <sys/cdefs.h>
  35
  36 __FBSDID("$FreeBSD: src/usr.bin/vis/foldit.c,v 1.6 2001/12/11 23:02:44 markm Exp $");
  37
  38 #ifndef lint
  39 static const char sccsid[] = "@(#)foldit.c      8.1 (Berkeley) 6/6/93";
  40 #endif
  41
  42 #include <stdio.h>
  43
  44 #include "extern.h"
  45
  46 int
  47 foldit(chunk, col, max)
  48         char *chunk;
  49         int col, max;
  50 {
  51         char *cp;
  52
  53         /*
  54          * Keep track of column position. Insert hidden newline
  55          * if this chunk puts us over the limit.
  56          */
  57 again:
  58         cp = chunk;
  59         while (*cp) {
  60                 switch(*cp) {
  61                 case '\n':
  62                 case '\r':
  63                         col = 0;
  64                         break;
  65                 case '\t':
  66                         col = (col + 8) &~ 07;
  67                         break;
  68                 case '\b':
  69                         col = col ? col - 1 : 0;
  70                         break;
  71                 default:
  72                         col++;
  73                 }
  74                 if (col > (max - 2)) {
  75                         printf("\\\n");
  76                         col = 0;
  77                         goto again;
  78                 }
  79                 cp++;
  80         }
  81         return (col);
  82 }