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From: dockery@griffin.cuc.ab.ca (Sean Dockery)
Subject: Re: Warp Six BBS 2.5 (description)
Message-ID: <CrM85q.77A@griffin.cuc.ab.ca>
Organization: Griffin Software Development
References: <2tpqal$8fb@netaxs.com> <2tschj$jck@blue.weeg.uiowa.edu>
Date: Sat, 18 Jun 1994 23:05:49 GMT
Lines: 79

snelson@blue.weeg.uiowa.edu wrote the following article:

| I know how to make this change with the Davex 'tr' command after dnloading,
| but evidently the Unix 'tr' command works differently.  Can someone tell
| me how to change \012\040\040\040\040\012 to \040\040\040\040\040\040
| in unix?  Not all \012, just the ones in that pattern.  Then I can
| correct the ones on grind.isca.uiowa.edu:apple2/apple8/bbs/Warp6.v25
| without having to dn/up load all of them with Kermit [SLOW......] :)

tr is a character translator, not a pattern replacement utility.

It is probably easier to handle the conversion with either awk or sed, but
I am not sure how to handle control characters in regular expressions with
either.

Anyways, I hacked this together in about ten minutes.
---------------------------------------------------------------------------
/* filter.c */

#include <stdio.h>		/* sprintf, fprintf, putchar, getchar, EOF */
#include <stdlib.h>		/* malloc, free */

#define NIL(tag) ((tag) 0)	/* remove dependency on "NULL" macro */

int main (int argc, char **argv)
{
    int ch = 0, i, index = 0;
    char *token;

    if ((token = (char *) malloc (7)) == NIL (char *))
    {
	fprintf (stderr, "main: malloc failure\n");
	exit (1);
    }
    sprintf (token, "%c%c%c%c%c%c", 012, 040, 040, 040, 040, 012);

    ch = getchar ();		/* prime while loop */
    while (ch != EOF)
    {
	if (ch == token[index])	/* character matches next space in token? */
	    index++;

	else if (index > 0)	/* abstract buffer non-empty? */
	{
	    for (i = 0; i < index; i++) /* flush matched-so-far */
		putchar (token[i]);
	    putchar (ch);	/* and first mis-match */
	    index = 0;
	}

	else			/* only single character mis-match */
	    putchar (ch);


	if (index == 6)		/* complete match? */
	{
	    printf ("%c%c%c%c%c%c", 040, 040, 040, 040, 040, 040);
	    index = 0;
	}

	ch = getchar ();
	if (ch == EOF && index > 0) /* if EOF, flush matched-so-far */
	    for (i = 0; i < index; i++)
		putchar (token[i]);
    }
    free (token);		/* no memory leaks here */

    return 0;
} /* main */
---------------------------------------------------------------------------
It compiles with `gcc -ansi -Wall -g filter.c' without no warnings.  From
my quick tests (from stdin,) it seems to be working properly.  Invoke it
using `./a.out < infile.bxy > outfile.bxy'.

|   --Steve  (steven-nelson@uiowa.edu)
-- 
Sean Dockery                        |  Tickle us, do we not laugh?
Griffin Software Development Group  |  Prick us, do we not bleed?
dockery@griffin.cuc.ab.ca           |  Wrong us, shall we not revenge?