usr.bin/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  * @(#)foldit.c 8.1 (Berkeley) 6/6/93
  34  * $FreeBSD: src/usr.bin/vis/foldit.c,v 1.4 1999/08/28 01:07:25 peter Exp $
  35  * $DragonFly: src/usr.bin/vis/foldit.c,v 1.4 2008/10/16 01:52:34 swildner Exp $
  36  */
  37
  38 #include <stdio.h>
  39
  40 int
  41 foldit(char *chunk, int col, int max)
  42 {
  43         char *cp;
  44
  45         /*
  46          * Keep track of column position. Insert hidden newline
  47          * if this chunk puts us over the limit.
  48          */
  49 again:
  50         cp = chunk;
  51         while (*cp) {
  52                 switch(*cp) {
  53                 case '\n':
  54                 case '\r':
  55                         col = 0;
  56                         break;
  57                 case '\t':
  58                         col = col + 8 &~ 07;
  59                         break;
  60                 case '\b':
  61                         col = col ? col - 1 : 0;
  62                         break;
  63                 default:
  64                         col++;
  65                 }
  66                 if (col > (max - 2)) {
  67                         printf("\\\n");
  68                         col = 0;
  69                         goto again;
  70                 }
  71                 cp++;
  72         }
  73         return (col);
  74 }