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. 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  */
  32
  33 #include <stdio.h>
  34
  35 #include "extern.h"
  36
  37 int
  38 foldit(const char *chunk, int col, int max)
  39 {
  40         const char *cp;
  41
  42         /*
  43          * Keep track of column position. Insert hidden newline
  44          * if this chunk puts us over the limit.
  45          */
  46 again:
  47         cp = chunk;
  48         while (*cp) {
  49                 switch(*cp) {
  50                 case '\n':
  51                 case '\r':
  52                         col = 0;
  53                         break;
  54                 case '\t':
  55                         col = (col + 8) &~ 07;
  56                         break;
  57                 case '\b':
  58                         col = col ? col - 1 : 0;
  59                         break;
  60                 default:
  61                         col++;
  62                 }
  63                 if (col > (max - 2)) {
  64                         printf("\\\n");
  65                         col = 0;
  66                         goto again;
  67                 }
  68                 cp++;
  69         }
  70         return (col);
  71 }