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  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#)foldit.c 8.1 (Berkeley) 6/6/93
  30  * $FreeBSD: src/usr.bin/vis/foldit.c,v 1.4 1999/08/28 01:07:25 peter Exp $
  31  * $DragonFly: src/usr.bin/vis/foldit.c,v 1.4 2008/10/16 01:52:34 swildner Exp $
  32  */
  33
  34 #include <stdio.h>
  35
  36 int
  37 foldit(char *chunk, int col, int max)
  38 {
  39         char *cp;
  40
  41         /*
  42          * Keep track of column position. Insert hidden newline
  43          * if this chunk puts us over the limit.
  44          */
  45 again:
  46         cp = chunk;
  47         while (*cp) {
  48                 switch(*cp) {
  49                 case '\n':
  50                 case '\r':
  51                         col = 0;
  52                         break;
  53                 case '\t':
  54                         col = col + 8 &~ 07;
  55                         break;
  56                 case '\b':
  57                         col = col ? col - 1 : 0;
  58                         break;
  59                 default:
  60                         col++;
  61                 }
  62                 if (col > (max - 2)) {
  63                         printf("\\\n");
  64                         col = 0;
  65                         goto again;
  66                 }
  67                 cp++;
  68         }
  69         return (col);
  70 }